Thermonuclear weapons. Fourth generation nuclear weapons are being created
Concept nuclear weapons combines explosive devices in which explosion energy is generated by the fission or fusion of nuclei. In the narrow sense, under nuclear weapons understand explosive devices that use the energy released during the fission of heavy nuclei. Devices that use the energy released during the fusion of light nuclei are called thermonuclear.
Nuclear weapons
The nuclear reaction, the energy of which is used in nuclear explosive devices, consists of the fission of a nucleus as a result of the capture of a neutron by this nucleus. The absorption of a neutron can lead to the fission of almost any nucleus, however, for the vast majority of elements, the fission reaction is possible only if the neutron, before being absorbed by the nucleus, had an energy exceeding a certain threshold value. The possibility of practical use of nuclear energy in nuclear explosive devices or in nuclear reactors is due to the existence of elements whose nuclei are fissioned under the influence of neutrons of any energy, including arbitrarily low. Substances with similar properties are called fissile substances.
The only fissile substance found in nature in appreciable quantities is the isotope of uranium with a nuclear mass of 235 atomic mass units (uranium-235). The content of this isotope in natural uranium is only 0.7%. The remainder is uranium-238. Since the chemical properties of the isotopes are exactly the same, separating uranium-235 from natural uranium requires a rather complex process of isotope separation. As a result, you can get highly enriched uranium, containing about 94% uranium-235, which is suitable for use in nuclear weapons.
Fissile substances can be obtained artificially, and the least difficult from a practical point of view is obtaining plutonium-239, formed as a result of the capture of a neutron by a uranium-238 nucleus (and the subsequent chain of radioactive decays of intermediate nuclei). A similar process can be carried out in a plant operating on natural or slightly enriched uranium. In the future, plutonium can be separated from spent reactor fuel in the process of chemical reprocessing of the fuel, which is noticeably simpler than the isotope separation process carried out when producing weapons-grade uranium.
Other fissile substances can also be used to create nuclear explosive devices, for example uranium-233, obtained by irradiation in a nuclear reactor of thorium-232. However, only uranium-235 and plutonium-239 have found practical use, primarily due to the relative ease of obtaining these materials.
The possibility of practical use of the energy released during nuclear fission is due to the fact that the fission reaction can have a chain, self-sustaining nature. Each fission event produces approximately two secondary neutrons, which, when captured by the nuclei of the fissile material, can cause them to fission, which in turn leads to the formation of even more neutrons. When special conditions are created, the number of neutrons, and therefore fission events, increases from generation to generation.
The dependence of the number of fission events on time can be described using the so-called neutron multiplication factor k, equal to the difference between the number of neutrons produced in one fission event and the number of neutrons lost due to absorption that does not lead to fission, or due to leaving the mass of the fissile substance . The parameter k, therefore, corresponds to the number of fission events that causes the decay of one nucleus. If the parameter k is less than one, then the fission reaction does not have a chain nature, since the number of neutrons capable of causing fission is less than their initial number. When the value k=1 is reached, the number of neutrons causing fission, and therefore decay events, does not change from generation to generation. The fission reaction acquires a chain, self-sustaining character. The state of matter in which it is realized chain reaction division with k=1 is called critical. When k>1 they speak of a supercritical state.
The dependence of the number of fission events on time can be presented as follows:
N=N o *exp((k-1)*t/T)
- N- the total number of fission events that occurred during the time t from the beginning of the reaction,
- N 0— the number of nuclei that underwent fission in the first generation, k-neutron multiplication factor,
- T is the time of “generational change,” i.e. the average time between successive acts of fission, the characteristic value of which is 10 -8 seconds.
If we assume that the chain reaction begins with one fission event and the multiplication factor is 2, then it is easy to estimate the number of generations required to release energy equivalent to the explosion of 1 kiloton of trinitrotoluene (10 12 calories or 4.1910 12 J). Since each fission event releases energy equal to approximately 180 MeV (2.910 -11 J), 1.4510 23 decay events should occur (which corresponds to the fission of approximately 57 g of fissile material). A similar number of decays will occur within approximately 53 generations of fissile nuclei. The entire process will take about 0.5 microseconds, with most of the energy released during the last few generations. Extending the process by just a few generations will lead to a significant increase in the energy released. Thus, to increase the explosion energy by 10 times (up to 100 kt), only five additional generations are needed.
The main parameter that determines the possibility of a fission chain reaction and the rate of energy release during this reaction is the neutron multiplication factor. This coefficient depends both on the properties of fissile nuclei, such as the number of secondary neutrons, cross sections of fission and capture reactions, and on external factors that determine the loss of neutrons caused by their escape from the mass of the fissile substance. The probability of neutron escape depends on the geometric shape of the sample and increases with increasing surface area. The probability of neutron capture is proportional to the concentration of nuclei of the fissile substance and the length of the path that the neutron travels in the sample. If we take a spherical sample, then as the mass of the sample increases, the probability of neutron capture leading to fission increases faster than the probability of its escape, which leads to an increase in the multiplication factor. The mass at which such a sample reaches a critical state (k=1) is called critical mass fissile substance. For highly enriched uranium, the critical mass value is about 52 kg, for weapons-grade plutonium - 11 kg. The critical mass can be reduced by approximately half by surrounding the fissile material sample with a layer of material that reflects neutrons, such as beryllium or natural uranium.
A chain reaction is also possible in the presence of a smaller amount of fissile material. Since the probability of capture is proportional to the concentration of nuclei, an increase in the density of the sample, for example as a result of its compression, can lead to the appearance of a critical state in the sample. It is this method that is used in nuclear explosive devices, in which a mass of fissile material in a subcritical state is converted into a supercritical state using a directed explosion, subjecting the charge to a high degree of compression. The minimum amount of fissile material required to carry out a chain reaction depends mainly on the degree of compression achievable in practice.
The degree and speed of compression of the mass of fissile material determine not only the amount of fissile material necessary to create an explosive device, but also explosion power. The reason for this is the fact that the energy released during the chain reaction leads to rapid heating of the mass of fissile material and, as a result, to the scattering of this mass. After some time, the charge loses criticality and the chain reaction stops. Since the total energy of the explosion depends on the number of nuclei that managed to undergo fission during the time during which the charge was in a critical state, in order to obtain a sufficiently large explosion power it is necessary to keep the mass of fissile material in a critical state for as long as possible. In practice, this is achieved by rapidly compressing the charge using a directed explosion, so that at the moment the chain reaction begins, the mass of fissile material has a very large margin of criticality.
Since the charge is in a critical state during the compression process, it is necessary to eliminate extraneous sources of neutrons that could start a chain reaction before the charge reaches the required degree of criticality. The premature start of a chain reaction will lead, firstly, to a decrease in the rate of energy release, and secondly, to an earlier dispersion of the charge and its loss of criticality. After the mass of fissile material has reached a critical state, a chain reaction can begin from acts of spontaneous fission of uranium or plutonium nuclei. However, the intensity of spontaneous fission turns out to be insufficient to ensure the necessary degree of synchronization of the moment of the beginning of the chain reaction with the process of compression of matter and to provide a sufficiently large number of neutrons in the first generation. To solve this problem, nuclear explosive devices use a special neutron source, which provides an “injection” of neutrons into the mass of fissile material. The moment of “injection” of neutrons must be carefully synchronized with the compression process, since the onset of a chain reaction too early will lead to the rapid onset of dispersion of the fissile material and, consequently, to a significant decrease in the explosion energy.
The first nuclear explosive device was detonated by the United States on July 16, 1945 in Alamogordo, New Mexico. The device was a plutonium bomb that used a directed explosion to create criticality. The power of the explosion was about 20 kt. In the USSR, the first nuclear explosive device similar to the American one exploded on August 29, 1949.
Thermonuclear weapons
In thermonuclear weapons, the explosion energy is generated during fusion reactions of light nuclei such as deuterium, tritium, which are isotopes of hydrogen or lithium. Such reactions can only occur at very high temperatures, at which the kinetic energy of the nuclei is sufficient to bring the nuclei together to a sufficiently small distance. The temperatures in question are around 10 7 -10 8 K.
The use of fusion reactions to increase the power of an explosion can be done in different ways. The first method involves placing a container of deuterium or tritium (or lithium deuteride) inside a conventional nuclear device. The high temperatures that arise at the moment of the explosion lead to the fact that the nuclei of light elements enter into a reaction, due to which additional energy is released. Using this method, you can significantly increase the power of the explosion. At the same time, the power of such an explosive device is still limited by the finite time of dispersion of the fissile material.
Another way is to create multi-stage explosive devices, in which, due to a special configuration of the explosive device, the energy of a conventional nuclear charge (the so-called primary charge) is used to create the necessary temperatures in a separately located “secondary” thermonuclear charge, the energy of which, in turn, can be used to detonate the third charge, etc. The first test of such a device, the “Mike” explosion, was carried out in the USA on November 1, 1952. In the USSR, a similar device was first tested on November 22, 1955. The power of an explosive device designed in this way can be arbitrarily large. The most powerful nuclear explosion was carried out using a multi-stage explosive device. The power of the explosion was 60 Mt, and only one third of the device’s power was used.
Sequence of events during a nuclear explosion
The release of a huge amount of energy that occurs during the fission chain reaction leads to rapid heating of the substance of the explosive device to temperatures of the order of 10 7 K. At such temperatures, the substance is an intensely emitting ionized plasma. At this stage, about 80% of the explosion energy is released in the form of electromagnetic radiation energy. The maximum energy of this radiation, called primary, falls in the X-ray range of the spectrum. The further course of events during a nuclear explosion is determined mainly by the nature of the interaction of primary thermal radiation with the environment surrounding the epicenter of the explosion, as well as the properties of this environment.
If the explosion is carried out at a low altitude in the atmosphere, the primary radiation of the explosion is absorbed by the air at distances of the order of several meters. Absorption of X-rays results in the formation of an explosion cloud characterized by very high temperatures. In the first stage, this cloud grows in size due to the radiative transfer of energy from the hot interior of the cloud to its cold surroundings. The temperature of the gas in a cloud is approximately constant throughout its volume and decreases as it increases. At the moment when the temperature of the cloud drops to approximately 300 thousand degrees, the speed of the cloud front decreases to values comparable to the speed of sound. At this moment it is formed shock wave, the front of which “breaks away” from the boundary of the explosion cloud. For an explosion with a power of 20 kt, this event occurs approximately 0.1 ms after the explosion. The radius of the explosion cloud at this moment is about 12 meters.
The intensity of the thermal radiation of the explosion cloud is entirely determined by the apparent temperature of its surface. For some time, the air heated as a result of the passage of the blast wave masks the explosion cloud, absorbing the radiation emitted by it, so that the temperature of the visible surface of the explosion cloud corresponds to the temperature of the air behind the shock wave front, which drops as the size of the front increases. About 10 milliseconds after the start of the explosion, the temperature in the front drops to 3000°C and it again becomes transparent to the radiation of the explosion cloud. The temperature of the visible surface of the explosion cloud begins to rise again and approximately 0.1 seconds after the start of the explosion reaches approximately 8000°C (for an explosion with a power of 20 kt). At this moment, the radiation power of the explosion cloud is maximum. After this, the temperature of the visible surface of the cloud and, accordingly, the energy emitted by it quickly drops. As a result, the bulk of the radiation energy is emitted in less than one second.
The formation of a pulse of thermal radiation and the formation of a shock wave occurs at the earliest stages of the existence of the explosion cloud. Since the cloud contains the bulk of the radioactive substances formed during the explosion, its further evolution determines the formation of a trace of radioactive fallout. After the explosion cloud cools down so much that it no longer emits in the visible region of the spectrum, the process of increasing its size continues due to thermal expansion and it begins to rise upward. As the cloud rises, it carries with it a significant mass of air and soil. Within a few minutes, the cloud reaches a height of several kilometers and can reach the stratosphere. The rate at which radioactive fallout occurs depends on the size of the solid particles on which it condenses. If, during its formation, the explosion cloud reaches the surface, the amount of soil entrained during the rise of the cloud will be quite large and radioactive substances will settle mainly on the surface of soil particles, the size of which can reach several millimeters. Such particles fall to the surface in relative proximity to the epicenter of the explosion, and their radioactivity practically does not decrease during the fallout.
If the explosion cloud does not touch the surface, the radioactive substances contained in it condense into much smaller particles with characteristic sizes of 0.01-20 microns. Since such particles can exist for quite a long time in the upper layers of the atmosphere, they are scattered over a very large area and in the time elapsed before they fall to the surface, they manage to lose a significant portion of their radioactivity. In this case radioactive trace practically not observed. The minimum height at which an explosion does not lead to the formation of a radioactive trace depends on the power of the explosion and is approximately 200 meters for an explosion with a power of 20 kt and about 1 km for an explosion with a power of 1 Mt.
The shock wave, formed in the early stages of the existence of an explosion cloud, is one of the main damaging factors of an atmospheric nuclear explosion. The main characteristics of a shock wave are the peak overpressure and the dynamic pressure at the wave front. The ability of objects to withstand the impact of a shock wave depends on many factors, such as the presence of load-bearing elements, construction material, and orientation relative to the front. An overpressure of 1 atm (15 psi) occurring 2.5 km from a 1 Mt ground explosion could destroy a multi-story reinforced concrete building. To withstand the effects of a shock wave, military facilities, especially ballistic missile silos, are designed in such a way that they can withstand excess pressures of hundreds of atmospheres. The radius of the area in which a similar pressure is created during an explosion of 1 Mt is about 200 meters. Accordingly, the accuracy of attacking ballistic missiles plays a special role in hitting fortified targets.
At the initial stages of the existence of a shock wave, its front is a sphere with its center at the point of explosion. After the front reaches the surface, a reflected wave is formed. Since the reflected wave propagates in the medium through which the direct wave has passed, its speed of propagation turns out to be slightly higher. As a result, at some distance from the epicenter, two waves merge near the surface, forming a front characterized by approximately twice the excess pressure values. Since for an explosion of a given power the distance at which such a front is formed depends on the height of the explosion, the height of the explosion can be selected to obtain maximum values of excess pressure over a certain area. If the purpose of the explosion is to destroy fortified military installations, the optimal height of the explosion is very low, which inevitably leads to the formation of a significant amount of radioactive fallout.
Another damaging factor of nuclear weapons is penetrating, which is a stream of high-energy neutrons and gamma rays generated both directly during the explosion and as a result of the decay of fission products. Along with neutrons and gamma rays, nuclear reactions also produce alpha and beta particles, the influence of which can be ignored due to the fact that they are very efficiently retained at distances of the order of several meters. Neutrons and gamma rays continue to be released for quite a long time after the explosion, affecting the radiation situation. The actual penetrating radiation usually includes neutrons and gamma rays appearing during the first minute after the explosion. This definition is due to the fact that in a time of about one minute, the explosion cloud manages to rise to a height sufficient for the radiation flux on the surface to become practically invisible.
The intensity of the penetrating flow and the distance at which its action can cause significant damage depend on the power of the explosive device and its design. , obtained at a distance of about 3 km from the epicenter of a thermonuclear explosion with a power of 1 Mt is sufficient to cause serious biological changes in the human body. A nuclear explosive device can be specially designed to increase the damage caused by penetrating radiation compared to the damage caused by other damaging factors (the so-called neutron weapon).
The processes occurring during an explosion at a significant altitude, where the air density is low, are somewhat different from those occurring during an explosion at low altitudes. First of all, due to the low density of air, absorption of primary thermal radiation occurs over much greater distances and the size of the explosion cloud can reach tens of kilometers. The processes of interaction of ionized particles of the cloud with the Earth’s magnetic field begin to have a significant influence on the process of formation of an explosion cloud. Ionized particles formed during the explosion also have a noticeable effect on the state of the ionosphere, making it difficult, and sometimes even impossible, for the propagation of radio waves (this effect can be used to blind radar stations).
One of the results of a high-altitude explosion is the emergence of a powerful electromagnetic pulse, spreading over a very large area. An electromagnetic pulse also occurs as a result of an explosion at low altitudes, but the strength of the electromagnetic field in this case quickly decreases as one moves away from the epicenter. In the case of a high-altitude explosion, the area of action of the electromagnetic pulse covers almost the entire surface of the Earth visible from the point of the explosion.
If the explosion is carried out underground, at the initial stage of the explosion, the absorption of primary thermal radiation by the environment leads to the formation of a cavity, the pressure in which increases to several million atmospheres within less than a microsecond. Next, within a fraction of a second, a shock wave is formed in the surrounding rock, the front of which overtakes the propagation of the explosion cavity. The shock wave causes the destruction of rock in the immediate vicinity of the epicenter and, weakening as it moves, gives rise to a series of seismic impulses that accompany the underground explosion. The explosion cavity continues to expand at a slightly lower speed than at the beginning, eventually reaching significant dimensions. Thus, the radius of the cavity formed by an explosion with a power of 150 kt can reach 50 meters. At this stage, the walls of the cavity are molten rock. At the third stage, the gas inside the cavity cools, and the molten rock solidifies at the bottom.
During the next stage, which can last from a few seconds to several hours, the pressure of the gases in the cavity drops so that they are no longer able to support the load of the upper layers of rock, which collapse down. The result is a vertical cigar-shaped structure filled with rock fragments. The dimensions of this structure depend on the nature of the rock in which the explosion was carried out. At the upper end of this structure there remains a cavity filled with radioactive gases. If the explosion occurs at an insufficiently deep depth, some of the gases may come to the surface.
It is the most destructive of all existing types of weapons. The number of nuclear weapons stockpiles on Earth reaches such a size that it is enough to destroy our planet several times over.
The new generation can sharply reduce the threshold of applicability of nuclear weapons and upset the existing strategic balance
In July 2006, during operations against militants of the Lebanese Hezbollah movement, the Israeli army used so-called bunker-busting bombs. At the same time, traces of enriched uranium were found in soil samples taken from bomb craters. At the same time, it was established that the radioactive decay of fission fragments was not accompanied by gamma radiation and the formation of a cesium isotope137, and the level of radiation, high inside the craters, decreased by about half at a distance of several meters from them.
The possibility cannot be ruled out that Israel used a new generation of nuclear weapons (nuclear weapons) in Southern Lebanon. It could have been delivered to Israel from the United States specifically for testing in combat conditions. Experts also suggest that similar weapons have already been used in Iraq and Afghanistan.
The absence of explosion products with a long decay period, as well as the insignificant radioactive contamination of the area, suggests that so-called “clean” thermonuclear ammunition could have been used in Southern Lebanon.
It is known that existing thermonuclear charges do not provide noticeable localization (both in time and area) of the scale of radioactive contamination of the environment, since the operation of their secondary unit is initiated by the fission reaction of heavy nuclei, which results in long-term radioactive contamination of the area.
Until now, it was precisely the latter circumstance that guaranteed a high threshold for the use of any types of current nuclear weapons, including low- and ultra-low-yield nuclear weapons. Now, if the results of independent examinations correspond to reality, we can talk about the emergence of new thermonuclear ammunition, the presence of which in service sharply reduces the psychological threshold for the applicability of nuclear weapons.
At the same time, “clean” thermonuclear ammunition is currently not subject to the restrictions of any of the existing international treaties and, according to the conditions of their use, formally become on the same level as conventional high-precision weapons (HPT), significantly surpassing the latter in destructive power.
There is still no consensus among experts on how far the United States and other leading foreign countries have progressed in the process of developing “clean” thermonuclear ammunition.
Meanwhile, indirect confirmation that, in conditions of strict secrecy, work on their creation is already underway in the United States in full swing, are the results of the practical activities of the current American administration to reform its strategic offensive forces (SNA).
Plans to create a new generation of thermonuclear munitions are also evidenced by the UK's efforts to change the existing structure of its strategic nuclear forces (SNF) and deploy new research infrastructure to study the problems of thermonuclear fusion.
The American leadership was the first among leading foreign states to realize that both the current “dirty” strategic nuclear weapons and the conventional WTO, which was much discussed in discussions about the need for an early transition to the concept of “non-nuclear deterrence”, now do not allow for the solution of all problems, assigned to strategic forces.
First of all, this concerns the guaranteed destruction of the enemy’s strategic highly protected and deeply buried targets, as well as the neutralization of the chemical and biological components of weapons of mass destruction (WMD).
New American nuclear strategy
An analysis of the new nuclear strategy adopted by the United States in 2002 shows that “clean” thermonuclear weapons are assigned the role of the cornerstone of a promising American strategic triad.
It also fits exceptionally clearly into the concept of “preventive” nuclear strikes recently adopted by the United States, according to which the US Armed Forces received the right to use nuclear weapons even in peacetime conditions.
The main provisions of the new US nuclear strategy are set out in the Nuclear Posture Review, presented to the US Congress in January 2002 (Nuclear Posture Review; hereinafter referred to as "Review..." for brevity).
In this conceptual document, the need to develop and adopt a new generation of nuclear weapons is justified as follows.
"...The modern nuclear arsenal, still reflecting the needs of the Cold War period, is characterized by low firing accuracy, limited retargeting capabilities, high power nuclear warhead chargers, silo-based, land-based and sea-based ballistic missiles with individually targeted warheads, low ability to hit buried targets," therefore, "...a nuclear strategy based solely on the capabilities of strategic offensive nuclear forces cannot provide deterrence to potential adversaries that the United States will face in the 21st century."
Further, the “Review...” formulates the basic requirements for a new generation of nuclear weapons: “... giving modern nuclear forces new capabilities should ensure: the destruction of objects that pose a threat, such as highly protected and buried targets, carriers of chemical and biological weapons; detection and destruction of mobile and moving targets; increasing shooting accuracy; limiting collateral damage when using nuclear weapons."
The Review also states that "providing such capabilities through intensive R&D and the deployment of new weapons systems is an imperative requirement for the creation of a new triad."
As can be seen, in the presented concept for the development of US nuclear forces, one of the key requirements for new types of nuclear weapons is the limitation of collateral damage during their use.
Since in “pure” thermonuclear ammunition the fusion reaction must be initiated by an energy source alternative to the fission reaction, the key point in their development is the replacement of the existing atomic “fuse” with a powerful and compact “detonator”.
Moreover, the latter must have sufficient energy to initiate a thermonuclear fusion reaction, and in terms of its weight and size characteristics, it must “fit” into the head parts of existing delivery vehicles.
It can be expected that the main damaging factors of new nuclear weapons will be instantaneous gamma-neutron radiation, a shock wave, and also light radiation. In this case, the penetrating radiation resulting from the radioactive decay of fission fragments will be relatively insignificant.
A number of experts believe that, first of all, new thermonuclear weapons will be used to equip high-precision guided missiles and aerial bombs. Moreover, its power can vary from a few to hundreds or more tons of TNT equivalent.
This will make it possible to use “clean” thermonuclear weapons to selectively destroy enemy targets located both in open areas (including mobile ballistic missile systems) and in high-voltage nuclear weapons systems, without fear of long-term radioactive contamination of the area.
Due to the absence of radioactive fallout, ground units will be able to operate in areas affected by nuclear weapons strikes, according to estimates, within 48 hours.
When new types of ammunition are used to destroy VZSZZ, including storage facilities for nuclear, chemical and biological weapons, neutron and gamma radiation arising directly at the moment of explosion will be almost completely absorbed by the layers of soil adjacent to the explosion site.
According to expert estimates, to destroy the VZSZZ located at a depth of over 300 meters, it will be necessary to create thermonuclear ammunition with a yield of about 100 kt or more.
According to American experts, the use of “clean” thermonuclear ammunition as warheads of anti-ballistic missiles should also significantly increase the effectiveness of the national missile defense system being created.
It is expected that such ammunition will have sufficiently wide destructive capabilities to guarantee the neutralization of enemy ballistic missile warheads equipped with WMD. At the same time, detonating a missile warhead over its territory, even at low altitude, will not lead to significant radioactive contamination of the environment.
New structure of American strategic forces
Let us now consider in more detail the changes that should occur directly in the structure of the American SNA.
Currently, the US SNA triad consists of intercontinental ballistic missiles (ICBMs), nuclear-powered ballistic missile submarines (SSBNs) and strategic bomber aircraft (SBA), which are armed with about 6,000 “dirty” nuclear warheads (DNW).
The new American nuclear strategy envisages the creation instead of a qualitatively different strategic triad, which will include:
- nuclear and non-nuclear strategic offensive weapons;
- active and passive strategic defensive weapons;
- updated military, research and industrial infrastructure.
The listed components of the new triad must be combined into a single whole by an improved system of communications, control, reconnaissance and adaptive planning.
The first (strike) component of the new strategic triad, in turn, will consist of two small triads: the triad of “global strike” forces and the old triad of the reduced strength SNA.
The “global strike” forces are planned to be deployed on the basis of SBA aircraft (including part of the current aviation component of the US SNA), multipurpose nuclear submarines (NPS) and surface ship carriers of sea-launched cruise missiles (SLCM), as well as parts of ICBMs and SLBMs from the SNA.
It is expected that the “global strike” forces will be armed with high-tech weapons in both conventional and nuclear (“clean” nuclear weapons) equipment.
The existing triad of the SNA within the framework of the Treaty on the Reduction of Strategic Offensive Potentials will undergo a radical reduction. By 2012, it will have 1,700-2,200 operationally deployed nuclear warheads in its arsenal. The remaining nuclear warheads will be transferred to active or passive reserve.
Operational control of both strike components of the new strategic triad is currently entrusted to the United Strategic Command (USC) of the US Armed Forces.
Based on the tasks assigned to the United States Armed Forces Command and the United States Joint Commands in forward zones, it can be assumed that “global strike” forces will be used to promptly launch preventive strikes on enemy strategic targets anywhere in the world, as well as conducting combat operations in regional conflicts.
The nuclear forces of the old SNA triad, which will retain existing types of strategic nuclear warheads in their arsenal, will continue to carry out the tasks of strategic nuclear deterrence. In the event of a radical change in the military-political situation, they will be used to launch “counter-force” or “counter-value” nuclear missile strikes against the enemy’s most important strategic targets, which are primarily considered to be Russia and China.
The second component of the US strategic triad will also consist of two components: strike (active) forces designed to promptly destroy enemy missile systems in their positional areas, as well as missile defense forces to intercept launched ballistic missiles and their warheads (passive forces).
In 2003, the United States denounced the Anti-Ballistic Missile Treaty. This circumstance allows them to begin the unlimited development, testing and deployment of anti-missile systems of any class with the deployment of their components both in the United States and abroad.
The new thermonuclear munition organically “fits” into plans to create the third component of the American strategic triad – an updated defense infrastructure.
According to the plans of the American leadership, it is called upon to quickly develop, test, produce and adopt promising offensive and defensive systems, including nuclear ones, in response to any emerging threats.
Currently, a powerful testing base has been deployed in the United States to study the problem of thermonuclear fusion in three different directions. There is no doubt that this base will be used not only for the industrial development of thermonuclear energy, but also for the creation of new thermonuclear charges.
So, at the Livermore Laboratory. Lawrence (California) to simulate nuclear tests, the world's most powerful laser thermonuclear installation (LTU) NIF (National Ignition Facility) was created, capable of realizing temperatures and pressures observed in nature only in the center of stars. The total installation cost is estimated to be $3.3 billion by 2008.
For the same purposes, the Los Alamos National Laboratory (New Mexico) and the Air Force Research Laboratory (Kirtland Air Force Base) jointly use the MTF (Magnetized Target Fusion) installation.
In the interests of studying physical processes with high energy density, the Sandia National Laboratory (Albuquerque) is upgrading a powerful electrical pulse generator, the so-called “Zmachine”.
The creation of new types of nuclear weapons is impossible without nuclear testing. For this reason, the Bush administration refused to resubmit the Comprehensive Nuclear Test Ban Treaty to the US Senate for ratification.
Being thus outside the legal framework of this treaty, the United States secured the opportunity to implement any nuclear testing programs at any time convenient for itself.
In parallel with scientific research, the United States is actively implementing measures to reduce the readiness period of the Nevada test site for the resumption of underground nuclear explosions from 36 to 12 months.
Preemptive Nuclear Strike Strategy
In 2005, the United States made important changes to its nuclear weapons strategy.
In accordance with the concept of “preemptive strikes,” better known as the “Bush Doctrine,” the US military has the right to carry out preemptive nuclear strikes in peacetime against countries that may pose a threat to the national security of the United States or its allies.
It should be especially emphasized that this doctrine also provides for the possibility of returning to the US Air Force and Navy (primarily surface combatants and submarines) carriers of tactical nuclear weapons removed in 1991.
It should be added that the United States is almost finishing the deployment of a strategic strike system based on Ohio-class nuclear submarines (SSGNs) equipped with Block IV Tomahawk cruise missiles, which represent the optimal means of delivering new nuclear weapons to targets.
In terms of its tactical and technical characteristics, the Tomahawk Block IV SLCM is the most advanced cruise missile of this class. Its maximum flight range is already 2800 km. The missile is capable of loitering in the target area for 2 hours to search for it or conduct additional reconnaissance. By equipping the SLCM with a satellite communication channel, it is also possible to retarget the missile in flight.
Each Ohio-class SSGN can accommodate up to 154 SLCMs.
In 2006, Great Britain (following the United States) began a radical revision of its nuclear deterrence doctrine.
Currently, the basis of the UK's strategic nuclear forces consists of four Vanguard-class missile-carrying submarines, each of which is equipped with 16 Trident 2 ballistic missiles with multiple warheads. The UK's current strategic nuclear forces appear to be an outdated model of countering the modern nuclear threat and are more in line with the realities of the Cold War than today. An alternative to the existing Vanguard system would be a weapon system deployed on submarines equipped with nuclear cruise missiles. It is particularly emphasized that in the interests of compliance with the Treaty on the Non-Proliferation of Nuclear Weapons, warheads for cruise missiles must be developed by the UK independently, and not obtained from the US.
The UK has already begun converting its multi-purpose nuclear submarines into Tomahawk SLCM carriers of the Block IV modification.
The Trafalgar nuclear submarine became the first boat in the British Navy capable of launching these missiles. The boat was equipped with the latest Tomahawk SLCM fire control system (TTWCS), developed by the American company Lockheed Martin, and the TSN (Tomahawk Strike Network) two-way satellite communication system, designed to retarget SLCMs of this modification in flight.
The presented version of the development of the UK's strategic nuclear forces is not something new. Back in the mid-1970s. The British Ministry of Defense studied the issue of adopting nuclear-armed American Tomahawk-class SLCMs into service with its strategic nuclear forces. However, in 1979, for a number of reasons, the British government abandoned this option in favor of the current Vanguard-class SSBNs with Trident2 SLBMs.
In parallel with the development of a new doctrine of nuclear deterrence, the UK is implementing a number of programs to develop nuclear infrastructure, which may be required to create nuclear weapons intended to equip a new component of the British strategic nuclear forces.
At the same time, the UK (like the USA) is concentrating its efforts on creating a testing base aimed at studying the problem of thermonuclear fusion. In this regard, it is expected that, following the United States, “clean” thermonuclear ammunition will soon appear in the arsenal of the updated British strategic nuclear forces.
In the summer of 2005, at a meeting of the Select Committee on Defense of the House of Commons of the British Parliament, it was announced that the UK nuclear weapons research center would be expanded. In the city of Aldermaston (Berkshire), the construction of an LTU has begun, costing about one billion pounds sterling, and it is announced that over 1 thousand specialists will be additionally employed in this center by 2008.
According to press reports, after the new Orion LTU is put into operation, it should ensure the reconstruction of physical processes occurring under nuclear reaction conditions. Within the framework of the Comprehensive Nuclear Test Ban Treaty, to which the UK is a party, the LTU will also be used to test elements of nuclear weapons being developed.
Thus, it can be assumed that in the near future the UK will focus on creating a new strategic nuclear “dyad”, which will consist of four Vanguard-class SSBNs with Trident2 SLBMs and several Trafalgar-class SSGNs equipped with Tomahawk SLCMs. with “clean” thermonuclear ammunition.
Vanguard-class SSBNs will be in service with the updated British strategic nuclear forces at least until 2020-2025, when the service life of the Trident2 ballistic missiles expires.
It is estimated that the UK could spend about £20 billion on creating a new strategic “dyad”.
In conclusion, attention should be paid to one important circumstance. In the event of successful development of a new generation of nuclear weapons, the United States and Great Britain will acquire significant military-technical superiority in the field of strategic weapons. The current “dirty” strategic nuclear weapons, by and large, are becoming unnecessary for them.
In this regard, it is necessary to be prepared for the fact that the United States and Great Britain, based on the thesis about the threat to world civilization from “dirty” nuclear weapons, may come up with an initiative for their universal ban. At the same time, only “clean” thermonuclear weapons should remain in the arsenal of nuclear countries, for which ~99% of the energy should be released in fusion reactions.
It is clear that thermonuclear ammunition, which now forms the basis of the strategic weapons of nuclear powers, will not meet such high requirements.
Thus, using controlled international organizations, the United States and Great Britain can pose a kind of scientific and technical barrier to the rest of the nuclear club participants. It could represent, for example, international obligations to develop and adopt exclusively thermonuclear warheads with a fragmentation activity of less than one percent.
This will require other nuclear states to urgently create a powerful research, production and testing base, huge financial and time costs.
At the same time, the existing military-technical reserve in the field of “clean” thermonuclear weapons will allow the United States and Great Britain to acquire unilateral military-political advantages for quite a long time.
Thus:
- The United States and Great Britain are actively developing a new generation of nuclear weapons, the use of which will help limit collateral damage. In this regard, they began to radically reform the structure and composition of their strategic nuclear forces, as well as the forms and methods of combat use of these forces.
- New nuclear weapons are outside the legal framework of all existing international treaties related to the development, testing, proliferation or use of nuclear weapons.
- The adoption of new generation nuclear weapons makes it possible to significantly reduce the threshold for the use of nuclear weapons and practically eliminate the difference between them and general-purpose weapons in terms of the conditions of combat use.
- The Russian Federation urgently needs to take adequate measures to strengthen its domestic deterrent capability.
Theoretical introduction. Thermonuclear weapons, as you might guess, are based on the organization of thermonuclear fusion reactions of atomic nuclei. Of all the reactions known to natural scientists that occur in the surrounding world, thermonuclear reactions have the greatest release of specific energy, i.e. energy per unit mass.
Scientists have found that thermonuclear processes are quite widespread in nature, in particular, they are a source of energy for stars. Our Sun is no exception. Nowadays, the Sun is an ordinary star, in the core of which thermonuclear reactions take place, producing helium nuclei from hydrogen nuclei.
ABOUT..
. GIANTS N
SUPERGIANTS
Every second the Sun consumes 6-1011 kg of hydrogen for the fusion reaction, with a yield of 4-109 kg of helium. According to astrophysicists, the currently observed state of dynamic equilibrium of our evolving star will last about 5 billion years.
WHITE** Dwarfs.
So, there is no reason for tactical concern yet. The intensity of thermonuclear reactions can be traced on the Hertzsprung-Russell diagram (Fig.
Rice. 6.32. Evolution of stars depending on the intensity of nuclear reactions
10,000 6,000 SURFACE TEMPERATURE, K
| m
|F| G I
- , which shows the dependence of the luminosity of stars on their temperature, which is also an indicator of the spectral class.
L = R52.
When one helium nucleus is formed from two hydrogen nuclei, an energy of 24 MeV is released. Let us recall that 1 eV is the energy that an electron acquires when passing through a potential difference equal to 1 V, 1 eV « 1.6-10 - 19 J. 1 kg of deuterium, an isotope of hydrogen, contains 1.5-1026 pairs of connecting nuclei.
The energy released from 1 kg of deuterium during helium synthesis can be determined as follows
E1 = 1.5 -1026 - 24 = 3.6 -1027 MeV = 1.62 -108 kW - hour.
As you know, deuterium is found in small concentrations in water. In terms of the average concentration of deuterium, it is potentially possible to obtain energy of about 6100 kWh from 1 liter of water, which is equivalent to burning 672 liters of gasoline, while spending about eight tons of oxygen on the oxidation reaction. To fuse two hydrogen nuclei into one helium nucleus, it is necessary that these positively charged nuclei overcome the Coulomb repulsive forces
r 1 Ze1 - Ze1 r
FK = -Lr.
4P880 r
To merge the original hydrogen nuclei, it is necessary to bring them closer to a distance commensurate with the size of the nucleus, i.e. at "3-1015 m. At this distance, the potential energy of two positive charges (hydrogen nuclei) will be equal to
1 Ze Ze
P = e= 7.68 10-14 J = 5 105 eV.
4P880 G
Two charged particles can approach at a distance commensurate with the size of the nucleus if they have a kinetic energy greater than or equal to half the potential interaction energy. It is known from molecular physics that the kinetic energy of the structural elements of matter during their chaotic thermal motion is determined by temperature
2-l
k 0 = mui.=2k,t,
0 2 2
which makes it possible to estimate the temperatures corresponding to thermonuclear fusion
13 0.5Kgt;P; -Пgt;Кgt;- kBT,
2 2 B
T.i. 7"68-10-‘‘ s 1.83-10* 0K.
-23
3kB 3 -1.4 -10
Temperatures only two orders of magnitude lower are realized within a short time, during atomic explosions and inside stars. According to the latest data from cosmophysicists, the temperature of the Sun lies in the range of 1.2-107 - 1.5-107 0K. At such relatively low temperatures, direct capture of a proton by a proton is possible
H1 + H1 ^ He2 + e+1 +v0,
In this case, the He2 nucleus is unstable and quickly turns into heavy hydrogen due to positron decay. A positron, colliding with its antipode - an electron, annihilates, turning into radiation
H2 + H1 ^ He2 + y (5.5 MeV),
Next, the interaction of unstable helium nuclei begins
He2 + He2 ^ He2 + 2H1 (12.8 MeV), which transform into a stable modification of helium. When 1 kg of hydrogen is converted into 883 g of helium, Am. 7 g of a substance is transformed in accordance with Oliver Heaviside's equation into radiation
E = Am - c° = 7-10-3 - 9-1016 = 6.3-1014 J.
So much energy is released during the complete oxidation of 1.6-1010 kg of motor gasoline. Naturally, such an energy output could not but interest the crown of Nature - humanity, which, in the best traditions of its evolutionary path, found a way to adapt all this energy efficiency exclusively for the extermination of its own kind and others like them.
The mass defect, discovered in studies of nuclear fission, means, in particular, that the mass of any stable nucleus is less than the sum of the masses of its constituent protons and neutrons. For example, the mass of the helium isotope He42 is less than the sum of the masses of two protons and two neutrons. Therefore, if two protons and two neutrons were brought into contact to form a helium nucleus, then this fusion would be accompanied by a decrease in mass. The decrease in mass on Am manifests itself in the release of a huge specific amount of energy (AE = Amc2). The formation of nuclei in the process of combining individual protons and neutrons or light nuclei is called nuclear fusion.
To clarify the details of the energy aspect of this process, let us turn again to the data in Fig. 4.14, which shows the curve of changes in the specific binding energy, i.e., energy per nucleon. Due to the negative sign of the mass defect, the fusion of nuclei of heavy elements (the right branch of the curve) will be accompanied by the release of energy.
The process will be highly endothermic, i.e. its implementation requires significant energy costs. The fusion reaction of two uranium nuclei, for example, is possible only if the combining nuclei have at least the same energy as that released when each of them fissions. The production of superheavy nuclei is a very energy-intensive and expensive enterprise, which is not possible at present.
The synthesis of light nuclei, on the contrary, leads to a mass defect that is associated with the release of significant binding energies. When two light nuclei combine, an exothermic process takes place.
When two protons and two neutrons merge into a helium nucleus, we get an energy gain of 28.2 MeV, and for 1 kg of synthesized helium this will be about 2-10 8 kWh. Even compared to the energy of nuclear fission, it’s impressive, very impressive.
At first glance, the method for carrying out the nuclear fusion reaction seems as simple as an amoeba; indeed, what’s simpler is to combine two deuterium nuclei and, here it is, helium:
D2 + D2 ^ He2 + 23.64 MeV, and the appearance of each new nucleus is accompanied by the release of energy 23.64 MeV. It is natural to assume that this energy is equal to the difference between the total binding energy of a helium atom nucleus (28.2 MeV), holding four nucleons together, and the total binding energy of two heavy hydrogen nuclei (2.28 MeV each). There are a number of other reactions that are used in fusion work. They are also indecently simple in appearance.
D2 + D2 ^ He2 + 3.27 MeV,
D2 + D2 ^ T° + p1 + 4.03 MeV,
Li36 + n0 ^ T° + He4 + 4.6 MeV.
The fusion of, for example, two heavy hydrogen nuclei is possible if they can be brought closer to the distance of action of nuclear forces, i.e. up to =3-10 - 15m. And for this it is necessary to overcome the Coulomb repulsion of protons in nuclei. An elementary calculation shows that at distances of this scale the electrostatic repulsion energy is equal to = 0.1 MeV.
The only obstacle to organizing a thermonuclear reaction at home is overcoming Coulomb repulsion, since protons and other light nuclei are always positively charged.
Calculations show that two opposing colliding protons should have a kinetic energy of about 250 keV each. This energy cannot be obtained by conventional heating, since even at a temperature of 107 0 K the particle energy barely reaches only = 1 keV. And it must be heated to temperatures of the order of 109 0K so that the energy of particle motion is sufficient to overcome the mutual repulsion of nuclei. At T = 10 K they come into direct contact, and the nuclei combine. The actual temperature required to maintain fusion reactions is slightly lower than the calculated one and is about 108 0K, which is due to the phenomenon of the tunnel effect.
In addition, according to the Maxwell distribution function, many particles have energies significantly higher than the average value (E) = kT.
After the Second World War, it became clear that when an atomic bomb explodes, temperatures of about 108 0K occur. The idea arose to use an atomic bomb as a fuse for a hydrogen bomb that would implement a nuclear fusion reaction.
It turned out to be quite simple to obtain an uncontrollable release of colossal amounts of energy during the explosion of a hydrogen bomb, after having already gained experience with conventional nuclear explosions.
A thermonuclear bomb is essentially composed of an atomic bomb and a thermonuclear charge. An atomic bomb explodes inside a shell filled with light elements capable of undergoing fusion reactions. For a very short time - millionths of a second, the temperature inside the still intact shell reaches several hundred million degrees (108 0K), and the pressure - hundreds of billions of atmospheres.
Under such extreme conditions, the fusion of deuterium and tritium nuclei into a helium nucleus begins
d2 + m° ^ He2 + n0, enormous energy is released in a very short time, i.e. an explosion occurs (Fig.
- . The energy released in a nuclear fusion reaction per given mass of fuel is greater than during nuclear fission. In addition, with nuclear fusion, the problem of radio disposal is not so acute. 6.33. Synthesis of active waste helium nuclei.
However, to implement controlled thermonuclear fusion, i.e. Non-explosive energy removal technically turned out to be a very difficult task. The whole point came down to creating and maintaining for a sufficiently long time the high temperatures necessary for nuclear fusion.
Any substance at the temperatures discussed is a special medium, which consists of nuclei and electrons unrelated to them. This state of matter is called plasma.
If you look at the corresponding section of the reference book on the physical properties of substances, you will find that of all their many, hafnium carbide has the highest melting point Tm = 4000 0K, even in it it is not possible to “contain” a high-temperature environment.
Conventional materials evaporate at a temperature of 104 0K at best, therefore, they are not suitable for thermonuclear technologies. But Mother Nature has decreed that plasma, having a huge number of free electrons, can pass electric current and react to an external magnetic field.
Hydrogen bomb. According to one of the versions circulating in the press, the history of the first practical use of the thermonuclear reaction begins in 1941. Japanese physicist Hagiwara from the University of Kyoto, which was not bombed in
- Mr. Americans, due to poor visibility, in a lecture to his students expressed the idea of the possibility of initiating a thermonuclear reaction between hydrogen nuclei under the conditions created by the explosion of an atomic bomb based on U235.
Figure 6.35. Klaus Fuchs
In September 1941, on the other side of the ocean, Enrico Fermi expressed a similar idea in a conversation with Edward Teller (Fig. 6. 34). Fermi's idea captured the scientist, who became a consistent and energetic initiator of the development of weapons of this type.
It must be said that this idea was also discussed at closed seminars by USSR physicists immediately after the deployment of the atomic project; at least not for Kurchatov, not for Flerov and other nuclear scientists, such an idea was not news.
For the time being, there was simply not enough time and energy to develop it on a systematic basis. The atomic race began, and all the efforts of very limited resources, both intellectual and material, were concentrated on it.
The idea of a "classic super" was formalized in the form of sketches at Los Alamos towards the end of 1945. In the spring
- Mr. Klaus Fuchs proposed, when using an atomic bomb as a fuse, to place a mixture of deuterium and tritium and the primary fuse in a beryllium oxide reflector heated by radiation.
Rice. 6.36. Teller-Ulam bomb diagram
In 1946, the idea of radiation implosion was born. The scheme proposed by Klaus Fuchs became the basis for the future Teller-Ulam configuration, which was included in modern textbooks on thermonuclear technology (Fig. 6.36).
The device consisted of two functional parts. A single housing contained an atomic charge in the form of a plutonium spherical bomb, which, when triggered, provided high temperatures and pressures and, in fact, thermonuclear fuel, colored cherry in the picture.
Modern nuclear physicists recognize that the ideas of the German physicist Fuchs, ahead of their time, became the basis for many subsequent designs of thermonuclear devices. Fuchs and Von Neumann filed an application on May 28, 1946 for the invention of a new design for an initiating compartment using radiation implosion.
Only five years later did the United States fully realize the enormous ideological potential of all Fuchs's proposals. At the end of August 1946, the tireless Teller published a report in which he developed a new design for a thermonuclear bomb under the romantic name “Alarm Clock”.
The new version of the bomb, as proposed by Teller, was to consist of alternating spherical layers of fissile materials and thermonuclear fuel, deuterium, tritium and their chemical compounds.
The fission chain reaction that occurred in one of the layers, due to the large number of fast neutrons, was supposed to initiate fission processes in neighboring layers, which should increase the energy release, especially heat.
The result of the atomic explosion should have caused the compaction of active fissile elements, i.e. volumetric convergence of nuclei of the original substance. The density of thermonuclear fuel increased with the increase in the rate of thermonuclear reactions.
However, the thermonuclear charge according to this scheme turned out to be unacceptably large, making it impossible even to theoretically consider its practical use. For some time, the “Classic Super” and “Alarmkick” projects were developed by Los Alamos specialists in parallel.
In January 1950, US President Harry Truman made a public statement officially commissioning Los Alamos scientists to develop a hydrogen bomb. Naturally, work in this direction has become more dynamic.
Rice. 6. 37. Fusion charge Mike
In September 1951, preparations began for the “Mike” thermonuclear charge for testing, which was successfully carried out on November 1, 1952. The explosion power was 10 Mt in TNT equivalent. Even with a stretch, it was difficult to call it a weapon (Fig. 6.37).
Complete lack of transport
The whiteness and dimensions corresponded to a decent size two-story building. The thermonuclear fission products were maintained at liquid nitrogen temperature. The thermonuclear charge, in this regard, was equipped with stationary refrigeration units capable of maintaining ultra-low temperatures during installation and testing.
In the USSR, before 1945, there was no opportunity to officially deal with issues of thermonuclear fusion, except for considering theoretical aspects. The country fought and created an atomic bomb at an accelerated pace, straining with all conceivable and inconceivable forces.
The first official document on thermonuclear weapons dates back to September 22, 1945, it was prepared in the name of I.V. Kurchatov nuclear scientist Yakov Ilyich Frenkel, where he theoretically substantiated the possibility of thermonuclear reactions occurring under the conditions of an atomic bomb explosion: “.... It seems interesting to use the high - billionth - temperatures developing during the explosion of an atomic bomb to carry out synthetic reactions (for example, the formation of helium from hydrogen), which are the source of energy for stars and which could further increase the energy released during the explosion of the main substance (uranium, bismuth, etc.).”
Rice. 6.38 Ya.I. Frenkel
When sending a note to Kurchatov, the scientist could not know that issues of thermonuclear reactions had long been discussed by the creators of atomic weapons and that Kurchatov had complete information about the state of affairs on thermonuclear issues at Los Alamos.
In September 1945, through foreign intelligence channels, Kurchatov received material about American work on combining a cannon-type atomic bomb based on U°°5 with a beryllium oxide reflector, an intermediate chamber with a deuterium-tritium mixture and a cylinder with liquid deuterium.
Open information about the possibility of creating a superbomb appeared in the British newspaper The Times on October 19, 1945, long before the testing of thermonuclear charges in the United States.
Naturally, such messages could not go unnoticed by the top leaders of the USSR and leading scientists involved in atomic programs. L.P. Beria instructed diplomats to clarify the information.
We turned to Niels Bohr, who had just returned to Denmark from the USA. Bohr considered it necessary to reassure everyone: “What does a superbomb mean? This is either a bomb of greater weight than the one already invented, or a bomb made from some new substance. Well, the first is possible, but pointless, since, I repeat, the destructive power of the bomb is already very great, and the second, I think, is unrealistic.” Despite his undoubted authority in the field of atomic physics, Bohr was not believed in our country.
At the insistence of Beria, the head of the atomic program Kurchatov gave instructions to leading specialists Yu.B. Khariton, Ya.B.
Zeldovich, I.I. Gurevich and I.Ya. Pomeranchuk to consider theoretically the question of the possibility of releasing the energy of light elements and present his conclusions at a meeting of the Technical
Nevertheless, I.V. Kurchatov turned to Yu.B. Khariton with instructions to consider Ria 6.39. Ya.B. Zeldovich
together with I. I. Gurevich, Ya. B. Zeldovich and
I. Ya. Pomeranchuk questioned the possibility of releasing the energy of light elements and presented considerations on this issue at a meeting of the Technical Council of the Special Committee.
Considerations by I.I. Gurevich, Ya.B. Zeldovich, I.Ya. Pomeranchuk and Yu.B. Khariton were outlined in the report “Use of Nuclear Energy of Light Elements,” the materials of which were heard at a meeting of the Technical Council on December 17, 1945.
The speaker was Ya. B. Zeldovich. The approach to solving the problem in the report was based on the idea of the possibility of excitation of nuclear detonation in a cylinder with deuterium during a nonequilibrium combustion regime.
The report considered at the meeting was published in full in the journal “Advances in Physical Sciences” No. 5 for 1991. According to the report of Ya.B. Zeldovich, at a meeting of the Technical Council on December 17, 1945, a decision was made that concerned only measurements of cross sections for reactions on light nuclei and did not contain instructions related to the organization and conduct of computational and theoretical research and work on the superbomb.
Nevertheless, in June 1946, a group of theorists from the Institute of Chemical Physics of the USSR Academy of Sciences, consisting of A.S. Kompaneets and S.P. Dyakov under the leadership of Ya.B. Zeldovich, within the framework of a research program on issues of nuclear combustion and explosion, began a theoretical consideration of the possibility of releasing the nuclear energy of light elements.
While the group Ya.B. Zeldovich conducted her research; in the USSR in 1946-1947, intelligence reports of an informational nature continued to be received regarding the work in the United States on a superbomb. These were supplemented by new reports in the open press, including an article by E. Teller in the February 1947 issue of the Bulletin of Atomic Scientists.
On September 28, 1947, in London, the first meeting of K. Fuchs, who returned from the USA to England, took place with a representative of Soviet intelligence A.S. Feklisov. A. S. Feklisov turned to K. Fuchs with 10 questions, the first of which related to the superbomb.
From the report of the meeting by A.S. Feklisov with K. Fuchs on September 28, 1947, it follows that K. Fuchs verbally reported that theoretical work on a superbomb was being carried out in the USA under the leadership of E. Teller and E. Fermi in Chicago.
K. Fuchs described some of the design features of the superbomb and the principles of its operation, and noted the use of tritium along with deuterium. K. Fuchs verbally reported that by the beginning of 1946, E. Fermi and E. Teller had proven that such a superbomb should operate effectively. However, A.S. Feklisov, not being a physicist, was able to reproduce the design features of the superbomb and its operation very approximately. K. Fuchs did not know whether practical work on creating a superbomb had begun in the United States and what their results would be.
In June 1948, the Council of Ministers of the USSR adopted Resolution No. 1989 - 773 “On supplementing the work plan of KB-11,” which, in particular, ordered the nuclear physics laboratory, together with the Physical Institute of the USSR Academy of Sciences, to conduct theoretical and experimental testing of the possibilities of creating a hydrogen bomb , which in the documents received the code RDS-6.
Only I.V. was familiar with materials on American developments. Kurchatov, who did not bother to introduce them to his employees.
So as not to hamper the freedom to search for alternative solutions. And they were not slow to follow.
Andrey Dmitrievich Sakharov, together with Yakov Borisovich Zeldovich, proposed a scheme for a combined bomb in which deuterium is used in a mixture with U238. In other words, regardless of E. Theiler, domestic scientists came up with the idea of a heterogeneous bomb, as it became known among the developers of “Sloika,” which was supposed to use the principle of ionization compression of thermonuclear fuel.
Igor Evgenievich Tamm, head A.D. Sakharov in graduate school, in November 1948 he sent a letter to the director of the Physical Institute of the USSR Academy of Sciences, S.I. Vavilov, in which he reported that the group of physicists he led had found the fundamental possibility of a new way of using detonation of deuterium, based on a special way of combining it with heavy water and natural uranium U238. In the same letter it was proposed to use the scheme Li6 + n = T + He4 + 4.8 MeV to carry out a thermonuclear reaction,
Rice. 6.41. I.E. Tamm
where lithium-6 deuterite is used as a thermonuclear weapon.
Sakharov proposed a scheme for additional charge of plutonium for pre-compression of the “puff”. This was the principle of the two-stage thermonuclear bomb design.
In the USA, as is known, on March 1, 1954, a powerful thermonuclear explosion was carried out, indicating that the thermonuclear program of competitors had moved from the theoretical stage to the practical plane.
This has given our scientists and politicians new strength. Literally in early April 1954, a new principle for constructing a thermonuclear bomb was discovered in KB-11.
Development of technical specifications for a new thermonuclear product RDS-37. In July 1955, a report was released justifying the design of the RDS-37 product.
The authors of the report were: E.N. Avrorin, V. A. Alexandrov, Yu.N. Babaev, G. A. Goncharov, Ya. B. Zeldovich, V. N. Klimov, G. E. Klinishov, B. N. Kozlov, E. S. Pavlovsky, E. M. Rabinovich, Yu.A. Romanov, A.D. Sakharov, Yu.A. Trutnev, V.P. Feodoritov, M.P. Shumaev, V.B. Adamsky, B.D. Bondarenko, Yu.S. Vakhrameev, G.M. Gandelman, G.A. Dvorovenko, N.A. Dmitriev, E.I. Zababakhin, V.G. Zagrafov, T.D. Kuznetsova, I.A. Kurilov, N.A. Popov, V.I. Ritus, V.N. Rodigin, L.P. Feoktistov, D.A. Frank-Kamenetsky, M.D. Churazov. Among the authors were mathematicians: I.A. Adamskaya, A. A. Bunatyan, I.M. Gelfand, A. A. Samarsky, K. A. Semendyaev, I.M. Khalatnikov, who, under the leadership of M.V. Keldysh and A.N. Tikhonov did a great job of providing theoretical support for the project.
Rice. 6.42. Product RDS-37
In November 1955 it was held
preliminary testing of a single-stage thermonuclear device, and on November 22, 1955, a two-stage thermonuclear charge, designed as an aircraft bomb, was successfully detonated (Fig. 6.42).
As A.D. said after the test.
Sakharov: “The test was the culmination of many years of effort, a triumph that opened the way to the development of a whole range of products with a variety of high characteristics (although unexpected difficulties would be encountered more than once).”
Thus, the next stage of creating thermonuclear weapons was successfully completed, and the following results were achieved:
- USSR scientists were the first in world practice (1952) to use highly efficient thermonuclear fuel lithium deuteride Li6. In the USA, the use of this material dates back to early 1956;
- Domestic scientists, already at the stage of the first tests, achieved a high accuracy of agreement between the theoretical parameters of a thermonuclear explosion and the characteristics observed in practice;
- The level of theoretical justification for the design was so high that it became possible to artificially reduce the power during experimental explosions in order to reduce the impact on the surrounding space;
- In two tests in 1955, thermonuclear charges were dropped for the first time from a serial TU-16 bomber.
Rice. 6.43. Bomber TU-95 at the moment the bombing began
On October 30, 1961, the world's most powerful thermonuclear bomb with a TNT equivalent of 50 MGt was detonated over Novaya Zemlya at an altitude of 4000 m above the earth's surface.
The bomb was dropped from a TU-95 bomber (Fig. 6.43). The crew was commanded by Major A. E. Durnovtsev.
This has never happened on the planet before. Despite the fact that half the charge was detonated, the flash in cloudy conditions was visible at a distance of thousands of kilometers.
Rice. 6.44. Domestic thermonuclear bomb with a yield of 100 MGt
This was an act of a one-time demonstration of force, accompanying specific circumstances of the political kitchen, the “great game” of intimidation between the superpowers.
It was a single product, the design of which, when fully “loaded” with nuclear fuel and while maintaining the same dimensions, made it possible to achieve a power of even 100 megatons. Such a terrifying explosion in combat conditions would instantly give rise to a fiery tornado that would cover a huge area.
After this test, the understanding came that the weapons created were not intended for a war for life - they were intended to destroy life.
Obviously, it was after this explosion that the political leaders of the “nuclear” powers realized the pointlessness of further building up their “thermonuclear muscles.” There were already enough weapons to put an end to many of the problems of modern civilization overnight.
Human use of nuclear materials
In 1939, the German scientist O. Hahn discovered the phenomenon of special radioactive decay of uranium nuclei under the influence of neutrons. Bombardment of uranium-235 nuclei with neutrons causes them to divide into two fragments, the masses of which are approximately 2:3. Fission fragments include elements from zinc to terbium with atomic numbers from 30 to 65 and mass numbers from 70 to 160. Fission fragments of uranium nuclei are unstable and undergo a series of beta decays, eventually turning into stable nuclei.
A characteristic feature of such chains is a gradual increase in half-lives in the direction from the beginning of the chain to its end. Excess energy from fission fragments is carried away by neutrons and gamma quanta (gamma rays). When uranium nuclei fission, 2-3 neutrons are usually emitted; with a lesser probability, there may be options with the emission of one, four or even five neutrons. The average energy of fission neutrons is about 2 MeV. The average number of gamma quanta emitted by excited fragment nuclei is about 8. Each of them carries an energy of 0.9 MeV.
The emitted neutrons, in turn, can bombard other uranium nuclei and thus continue the process of their fission. The ratio of the number of neutrons in any generation to the number of neutrons in the previous generation is called neutron multiplication factor. Under real conditions, some of these neutrons will be absorbed by impurities in uranium-235, and some will go beyond the uranium mass. But it is enough for the number of neutrons in each cycle to increase more than 1 time (the multiplication factor is greater than 1), and the chain fission process develops. The fission of atoms contained in 1 gram of uranium-235 releases energy equivalent to the combustion of 3,000 tons of coal or 2,000 tons of oil. To produce a chain reaction, a certain mass of uranium is required, which is called critical.
At that time, German scientists were unable to obtain chain reaction fission of uranium nuclei, but the discovery of O. Gan predetermined the beginning of the era of the use of atomic energy by man.
On December 2, 1942, on the sports ground of the University of Chicago, a group of nuclear physicists under the leadership of the great Italian scientist E. Fermi launched the first nuclear boiler, in which it took place self-sustaining controlled atomic reaction.
This success was preceded by almost half a century of research in the field of theoretical and experimental physics, conducted under the leadership of P. Curie, M. Sklodowska-Curie, E. Rutherford, N. Bohr, A. Einstein, M. Planck, F. Joliot-Curie, I. Joliot-Curie, L. Meitner, O. Gan, D. Chadwick, W. Heisenberg, I.V. Kurchatov and other outstanding atomic scientists.
Results carried out by the Fermi group chain reaction were put on a war footing from the very beginning, namely, the urgent creation of atomic weapons in the United States in order to get ahead of Hitler, whose physicists were working in the same direction.
In 1944, in the USA, under the leadership of E. Fermi, an atomic bomb was created and tested, and in August 1945, the Japanese cities of Hiroshima and Nagasaki were subjected to atomic bombing. Then a third of the population of these cities died. In subsequent years, many died from radiation sickness, leukemia and other ailments associated with radiation exposure.
On December 25, 1946, under the leadership of I.V. Kurchatov, the first Soviet controlled uranium-graphite reactor was launched, which subsequently produced weapons grade plutonium, used as a nuclear charge instead of uranium-235 in the production of atomic weapons. The first Soviet atomic bomb was tested on August 29, 1949.
An atomic explosion produces fission products and a portion of undivided atoms of uranium-235 or plutonium-239 remains, which are released into the atmosphere during a ground explosion.
Subsequently, the USSR created and tested a hydrogen bomb in 1953, the action of which is based on thermonuclear reaction interactions of deuterium and tritium:
This reaction occurs instantly (3 x 10 -6 seconds), but to start it requires a very high temperature, which can only be obtained during an atomic explosion. As a result, in a hydrogen bomb containing a mixture of deuterium and tritium, an atomic plutonium charge serves as a detonator.
The fission of uranium-235, plutonium-239, and especially the thermonuclear reaction, release a large number of neutrons. The latter bombard surrounding substances, turning them radioactive (induced radioactivity). In addition, a large amount of fission products is released into the atmosphere. The most important of them are cesium-137 and strontium-90.
Rice. 9. Diagram of an atomic bomb.
1 - charge of uranium-235 or plutonium-239; 2 - a conventional explosive (a fuse for connecting pieces of uranium in order to achieve a critical mass); 3 - high-density metal shell(I.V. Savelyev, 1987).