Our article is devoted to the history of creation and general principles of synthesis of such a device, sometimes called hydrogen. Instead of releasing explosive energy by splitting the nuclei of heavy elements like uranium, it generates even more energy by fusing the nuclei of light elements (such as isotopes of hydrogen) into one heavy one (such as helium).
Why is nuclear fusion preferable?
During a thermonuclear reaction, which consists in the fusion of the nuclei of the chemical elements participating in it, significantly more energy is generated per unit mass of a physical device than in a pure atomic bomb that implements a nuclear fission reaction.
In an atomic bomb, fissile nuclear fuel quickly, under the influence of the energy of detonation of conventional explosives, combines in a small spherical volume, where its so-called critical mass is created, and the fission reaction begins. In this case, many neutrons released from fissile nuclei will cause the fission of other nuclei in the fuel mass, which also release additional neutrons, leading to a chain reaction. It covers no more than 20% of the fuel before the bomb explodes, or perhaps much less if conditions are not ideal: as in the atomic bombs Little Kid dropped on Hiroshima and Fat Man that hit Nagasaki, efficiency (if such a term can be applied to them) apply) were only 1.38% and 13%, respectively.
The fusion (or fusion) of nuclei covers the entire mass of the bomb charge and lasts as long as neutrons can find thermonuclear fuel that has not yet reacted. Therefore, the mass and explosive power of such a bomb are theoretically unlimited. Such a merger could theoretically continue indefinitely. Indeed, the thermonuclear bomb is one of the potential doomsday devices that could destroy all human life.
What is a nuclear fusion reaction?
The fuel for the thermonuclear fusion reaction is hydrogen isotopes deuterium or tritium. The first differs from ordinary hydrogen in that its nucleus, in addition to one proton, also contains a neutron, and the tritium nucleus already has two neutrons. In natural water, there is one deuterium atom for every 7,000 hydrogen atoms, but from its quantity. contained in a glass of water, as a result of a thermonuclear reaction, the same amount of heat can be obtained as from the combustion of 200 liters of gasoline. At a 1946 meeting with politicians, the father of the American hydrogen bomb, Edward Teller, emphasized that deuterium provides more energy per gram of weight than uranium or plutonium, but costs twenty cents per gram compared with several hundred dollars per gram of fission fuel. Tritium does not occur in nature in a free state at all, so it is much more expensive than deuterium, with a market price of tens of thousands of dollars per gram, but the greatest amount of energy is released precisely in the fusion reaction of deuterium and tritium nuclei, in which the nucleus of a helium atom is formed and released neutron carrying away excess energy of 17.59 MeV
D + T → 4 He + n + 17.59 MeV.
This reaction is shown schematically in the figure below.
Is it a lot or a little? As you know, everything is learned by comparison. So, the energy of 1 MeV is approximately 2.3 million times more than that released during the combustion of 1 kg of oil. Consequently, the fusion of only two nuclei of deuterium and tritium releases as much energy as is released during the combustion of 2.3∙10 6 ∙17.59 = 40.5∙10 6 kg of oil. But we are talking about only two atoms. You can imagine how high the stakes were in the second half of the 40s of the last century, when work began in the USA and the USSR, which resulted in a thermonuclear bomb.
How it all began
As early as the summer of 1942, at the beginning of the atomic bomb project in the United States (the Manhattan Project) and later in a similar Soviet program, long before a bomb based on the fission of uranium nuclei was built, the attention of some participants in these programs was drawn to the device, which can use a much more powerful nuclear fusion reaction. In the USA, a supporter of this approach, and even, one might say, its apologist, was the above-mentioned Edward Teller. In the USSR, this direction was developed by Andrei Sakharov, a future academician and dissident.
For Teller, his fascination with thermonuclear fusion during the years of creating the atomic bomb was rather a disservice. As a participant in the Manhattan Project, he persistently called for the redirection of funds to implement his own ideas, the goal of which was a hydrogen and thermonuclear bomb, which did not please the leadership and caused tension in relations. Since at that time the thermonuclear direction of research was not supported, after the creation of the atomic bomb Teller left the project and began teaching, as well as researching elementary particles.
However, the outbreak of the Cold War, and most of all the creation and successful testing of the Soviet atomic bomb in 1949, became a new chance for the ardent anti-communist Teller to realize his scientific ideas. He returns to the Los Alamos laboratory, where the atomic bomb was created, and, together with Stanislav Ulam and Cornelius Everett, begins calculations.
The principle of a thermonuclear bomb
In order for the nuclear fusion reaction to begin, the bomb charge must be instantly heated to a temperature of 50 million degrees. The thermonuclear bomb scheme proposed by Teller uses for this purpose the explosion of a small atomic bomb, which is located inside the hydrogen casing. It can be argued that there were three generations in the development of her project in the 40s of the last century:
- Teller's variation, known as the "classic super";
- more complex, but also more realistic designs of several concentric spheres;
- the final version of the Teller-Ulam design, which is the basis of all thermonuclear weapon systems operating today.
Thermonuclear bombs of the USSR, whose creation was pioneered by Andrei Sakharov, went through similar design stages. He, apparently, completely independently and independently of the Americans (which cannot be said about the Soviet atomic bomb, created by the joint efforts of scientists and intelligence officers working in the USA) went through all of the above design stages.
The first two generations had the property that they had a succession of interlocking "layers", each of which reinforced some aspect of the previous one, and in some cases feedback was established. There was no clear division between the primary atomic bomb and the secondary thermonuclear one. In contrast, the Teller-Ulam thermonuclear bomb diagram sharply distinguishes between a primary explosion, a secondary explosion, and, if necessary, an additional one.
The device of a thermonuclear bomb according to the Teller-Ulam principle
Many of its details still remain classified, but it is reasonably certain that all thermonuclear weapons currently available are based on the device created by Edward Telleros and Stanislaw Ulam, in which an atomic bomb (i.e. the primary charge) is used to generate radiation, compresses and heats fusion fuel. Andrei Sakharov in the Soviet Union apparently independently came up with a similar concept, which he called the "third idea."
The structure of a thermonuclear bomb in this version is shown schematically in the figure below.
It was cylindrical in shape, with a roughly spherical primary atomic bomb at one end. The secondary thermonuclear charge in the first, not yet industrial samples, was made of liquid deuterium; somewhat later it became solid from a chemical compound called lithium deuteride.
The fact is that industry has long used lithium hydride LiH for balloon-free hydrogen transportation. The developers of the bomb (this idea was first used in the USSR) simply proposed taking its isotope deuterium instead of ordinary hydrogen and combining it with lithium, since it is much easier to make a bomb with a solid thermonuclear charge.
The shape of the secondary charge was a cylinder placed in a container with a lead (or uranium) shell. Between the charges there is a neutron protection shield. The space between the walls of the container with thermonuclear fuel and the bomb body is filled with special plastic, usually polystyrene foam. The bomb body itself is made of steel or aluminum.
These shapes have changed in recent designs such as the one shown below.
In it, the primary charge is flattened, like a watermelon or an American football ball, and the secondary charge is spherical. Such shapes fit much more efficiently into the internal volume of conical missile warheads.
Thermonuclear explosion sequence
When a primary atomic bomb detonates, in the first moments of this process a powerful X-ray radiation (neutron flux) is generated, which is partially blocked by the neutron shield, and is reflected from the inner lining of the housing surrounding the secondary charge, so that the X-rays fall symmetrically across its entire length
During the initial stages of a thermonuclear reaction, neutrons from an atomic explosion are absorbed by a plastic filler to prevent the fuel from heating up too quickly.
X-rays initially cause the appearance of a dense plastic foam that fills the space between the housing and the secondary charge, which quickly turns into a plasma state that heats and compresses the secondary charge.
In addition, the X-rays evaporate the surface of the container surrounding the secondary charge. The substance of the container, evaporating symmetrically relative to this charge, acquires a certain impulse directed from its axis, and the layers of the secondary charge, according to the law of conservation of momentum, receive an impulse directed towards the axis of the device. The principle here is the same as in a rocket, only if you imagine that the rocket fuel scatters symmetrically from its axis, and the body is compressed inward.
As a result of such compression of thermonuclear fuel, its volume decreases thousands of times, and the temperature reaches the level at which the nuclear fusion reaction begins. A thermonuclear bomb explodes. The reaction is accompanied by the formation of tritium nuclei, which merge with deuterium nuclei initially present in the secondary charge.
The first secondary charges were built around a rod core of plutonium, informally called a "candle", which entered into a nuclear fission reaction, i.e., another, additional atomic explosion was carried out in order to further raise the temperature to ensure the start of the nuclear fusion reaction. It is now believed that more efficient compression systems have eliminated the "candle", allowing further miniaturization of bomb design.
Operation Ivy
This was the name given to the tests of American thermonuclear weapons in the Marshall Islands in 1952, during which the first thermonuclear bomb was detonated. It was called Ivy Mike and was built according to the Teller-Ulam standard design. Its secondary thermonuclear charge was placed in a cylindrical container, which was a thermally insulated Dewar flask with thermonuclear fuel in the form of liquid deuterium, along the axis of which a “candle” of 239-plutonium ran. The dewar, in turn, was covered with a layer of 238-uranium weighing more than 5 metric tons, which evaporated during the explosion, providing symmetrical compression of the thermonuclear fuel. The container containing the primary and secondary charges was housed in a steel casing 80 inches wide by 244 inches long with walls 10 to 12 inches thick, the largest example of a forged product up to that time. The inner surface of the case was lined with sheets of lead and polyethylene to reflect radiation after the explosion of the primary charge and create plasma that heats the secondary charge. The entire device weighed 82 tons. A view of the device shortly before the explosion is shown in the photo below.
The first test of a thermonuclear bomb took place on October 31, 1952. The power of the explosion was 10.4 megatons. Attol Eniwetok, where it was produced, was completely destroyed. The moment of the explosion is shown in the photo below.
The USSR gives a symmetrical answer
The US thermonuclear championship did not last long. On August 12, 1953, the first Soviet thermonuclear bomb RDS-6, developed under the leadership of Andrei Sakharov and Yuli Khariton, was tested at the Semipalatinsk test site. From the description above, it becomes clear that the Americans at Enewetok did not actually detonate a bomb, but a type of ready-to-use ammunition, but rather a laboratory device, cumbersome and very imperfect. Soviet scientists, despite the small power of only 400 kg, tested a completely finished ammunition with thermonuclear fuel in the form of solid lithium deuteride, and not liquid deuterium, like the Americans. By the way, it should be noted that only the 6 Li isotope is used in lithium deuteride (this is due to the peculiarities of thermonuclear reactions), and in nature it is mixed with the 7 Li isotope. Therefore, special production facilities were built to separate lithium isotopes and select only 6 Li.
Reaching Power Limit
What followed was a decade of continuous arms race, during which the power of thermonuclear munitions continually increased. Finally, on October 30, 1961, in the USSR over the Novaya Zemlya test site in the air at an altitude of about 4 km, the most powerful thermonuclear bomb that had ever been built and tested, known in the West as the “Tsar Bomba,” was exploded.
This three-stage munition was actually developed as a 101.5-megaton bomb, but the desire to reduce radioactive contamination of the area forced the developers to abandon the third stage with a yield of 50 megatons and reduce the design yield of the device to 51.5 megatons. At the same time, the power of the explosion of the primary atomic charge was 1.5 megatons, and the second thermonuclear stage was supposed to give another 50. The actual power of the explosion was up to 58 megatons. The appearance of the bomb is shown in the photo below.
Its consequences were impressive. Despite the very significant height of the explosion of 4000 m, the incredibly bright fireball with its lower edge almost reached the Earth, and with its upper edge it rose to a height of more than 4.5 km. The pressure below the burst point was six times higher than the peak pressure of the Hiroshima explosion. The flash of light was so bright that it was visible at a distance of 1000 kilometers, despite the cloudy weather. One of the test participants saw a bright flash through dark glasses and felt the effects of the thermal pulse even at a distance of 270 km. A photo of the moment of the explosion is shown below.
It was shown that the power of a thermonuclear charge really has no limitations. After all, it was enough to complete the third stage, and the calculated power would be achieved. But it is possible to increase the number of stages further, since the weight of the Tsar Bomba was no more than 27 tons. The appearance of this device is shown in the photo below.
After these tests, it became clear to many politicians and military men both in the USSR and in the USA that the limit of the nuclear arms race had been reached and it needed to be stopped.
Modern Russia inherited the nuclear arsenal of the USSR. Today, Russia's thermonuclear bombs continue to serve as a deterrent to those seeking global hegemony. Let's hope they only play their role as a deterrent and never get blown up.
The sun as a fusion reactor
It is well known that the temperature of the Sun, or more precisely its core, reaching 15,000,000 °K, is maintained due to the continuous occurrence of thermonuclear reactions. However, everything that we could glean from the previous text speaks of the explosive nature of such processes. Then why doesn't the Sun explode like a thermonuclear bomb?
The fact is that with a huge share of hydrogen in the solar mass, which reaches 71%, the share of its isotope deuterium, the nuclei of which can only participate in the thermonuclear fusion reaction, is negligible. The fact is that deuterium nuclei themselves are formed as a result of the merger of two hydrogen nuclei, and not just a merger, but with the decay of one of the protons into a neutron, positron and neutrino (so-called beta decay), which is a rare event. In this case, the resulting deuterium nuclei are distributed fairly evenly throughout the volume of the solar core. Therefore, with its enormous size and mass, individual and rare centers of thermonuclear reactions of relatively low power are, as it were, smeared throughout its entire core of the Sun. The heat released during these reactions is clearly not enough to instantly burn out all the deuterium in the Sun, but it is enough to heat it to a temperature that ensures life on Earth.
On October 30, 1961, the most powerful explosion in human history occurred at the Soviet nuclear test site on Novaya Zemlya. The nuclear mushroom rose to a height of 67 kilometers, and the diameter of the “cap” of this mushroom was 95 kilometers. The shock wave circled the globe three times (and the blast wave demolished wooden buildings at a distance of several hundred kilometers from the test site). The flash of the explosion was visible from a distance of a thousand kilometers, despite the fact that thick clouds hung over Novaya Zemlya. For almost an hour there was no radio communication throughout the entire Arctic. The power of the explosion, according to various sources, ranged from 50 to 57 megatons (million tons of TNT).
However, as Nikita Sergeevich Khrushchev joked, they did not increase the power of the bomb to 100 megatons, only because in this case all the windows in Moscow would have been broken. But every joke has its share of a joke - the original plan was to detonate a 100 megaton bomb. And the explosion on Novaya Zemlya convincingly proved that creating a bomb with a capacity of at least 100 megatons, at least 200, is a completely feasible task. But 50 megatons is almost ten times the power of all the ammunition expended during the entire Second World War by all participating countries. Moreover, in the event of testing a product with a capacity of 100 megatons, only a melted crater would remain from the test site on Novaya Zemlya (and most of this island). In Moscow, the glass most likely would have survived, but in Murmansk they could have been blown out.
Model of a hydrogen bomb. Historical and Memorial Museum of Nuclear Weapons in Sarov
The device, detonated at an altitude of 4200 meters above sea level on October 30, 1961, went down in history under the name “Tsar Bomba”. Another unofficial name is “Kuzkina Mother”. But the official name of this hydrogen bomb was not so loud - the modest product AN602. This miracle weapon had no military significance - not in tons of TNT equivalent, but in ordinary metric tons, the “product” weighed 26 tons and it would have been problematic to deliver it to the “addressee”. It was a show of force - clear proof that the Soviet Union was capable of creating weapons of mass destruction of any power. What made the leadership of our country take such an unprecedented step? Of course, nothing more than a worsening of relations with the United States. More recently, it seemed that the United States and the Soviet Union had reached mutual understanding on all issues - in September 1959, Khrushchev visited the United States on an official visit, and a return visit to Moscow by President Dwight Eisenhower was also planned. But on May 1, 1960, an American U-2 reconnaissance aircraft was shot down over Soviet territory. In April 1961, American intelligence agencies organized the landing of well-prepared and trained Cuban emigrants in the Bay of Playa Giron (this adventure ended in a convincing victory for Fidel Castro). In Europe, the great powers could not decide on the status of West Berlin. As a result, on August 13, 1961, the capital of Germany was blocked by the famous Berlin Wall. Finally, in 1961, the United States deployed PGM-19 Jupiter missiles in Turkey - European Russia (including Moscow) was within range of these missiles (a year later, the Soviet Union would deploy missiles in Cuba and the famous Cuban Missile Crisis would begin). This is not to mention the fact that there was no parity in the number of nuclear charges and their carriers between the Soviet Union and America at that time - we could counter 6 thousand American warheads with only three hundred. So, the demonstration of thermonuclear power was not at all superfluous in the current situation.
Soviet short film about the testing of the Tsar Bomba
There is a popular myth that the superbomb was developed on Khrushchev’s orders in the same 1961 in record time - in just 112 days. In fact, the development of the bomb began in 1954. And in 1961, the developers simply brought the existing “product” to the required power. At the same time, the Tupolev Design Bureau was modernizing Tu-16 and Tu-95 aircraft for new weapons. According to initial calculations, the weight of the bomb should have been at least 40 tons, but aircraft designers explained to nuclear scientists that at the moment there are no carriers for a product with such a weight and there cannot be. Nuclear scientists promised to reduce the weight of the bomb to a quite acceptable 20 tons. True, such weight and such dimensions required a complete rework of the bomb compartments, fastenings, and bomb bays.
Hydrogen bomb explosion
Work on the bomb was carried out by a group of young nuclear physicists under the leadership of I.V. Kurchatova. This group also included Andrei Sakharov, who at that time had not yet thought about dissent. Moreover, he was one of the leading developers of the product.
Such power was achieved through the use of a multi-stage design - a uranium charge with a power of “only” one and a half megatons launched a nuclear reaction in a second-stage charge with a power of 50 megatons. Without changing the dimensions of the bomb, it was possible to make it three-stage (this is already 100 megatons). Theoretically, the number of stage charges could be unlimited. The design of the bomb was unique for its time.
Khrushchev hurried the developers - in October, the 22nd Congress of the CPSU was taking place in the newly built Kremlin Palace of Congresses, and the news about the most powerful explosion in the history of mankind should have been announced from the rostrum of the congress. And on October 30, 1961, Khrushchev received a long-awaited telegram signed by the Minister of Medium Engineering E.P. Slavsky and Marshal of the Soviet Union K.S. Moskalenko (test leaders):
"Moscow. The Kremlin. N.S. Khrushchev.The test on Novaya Zemlya was successful. The safety of testers and the surrounding population is ensured. The training ground and all participants completed the task of the Motherland. We're going back to the convention."
The explosion of the Tsar Bomba almost immediately served as fertile ground for all sorts of myths. Some of them were distributed ... by the official press. So, for example, Pravda called the Tsar Bomba nothing less than the yesterday of atomic weapons and argued that more powerful charges had already been created. There were also rumors about a self-sustaining thermonuclear reaction in the atmosphere. The reduction in the power of the explosion, according to some, was caused by the fear of splitting the earth's crust or...causing a thermonuclear reaction in the oceans.
But be that as it may, a year later, during the Cuban Missile Crisis, the United States still had an overwhelming superiority in the number of nuclear warheads. But they never decided to use them.
In addition, the mega-explosion is believed to have helped move forward the three-medium nuclear test ban negotiations that had been going on in Geneva since the late fifties. In 1959-60, all nuclear powers, with the exception of France, accepted a unilateral refusal to test while these negotiations were ongoing. But we talked below about the reasons that forced the Soviet Union not to comply with its obligations. After the explosion on Novaya Zemlya, negotiations resumed. And on October 10, 1963, the “Treaty Banning Nuclear Weapons Tests in the Atmosphere, Outer Space and Under Water” was signed in Moscow. As long as this Treaty is respected, the Soviet Tsar Bomba will remain the most powerful explosive device in human history.
Modern computer reconstruction
Contents of the article
HYDROGEN BOMB, a weapon of great destructive power (on the order of megatons in TNT equivalent), the operating principle of which is based on the reaction of thermonuclear fusion of light nuclei. The source of explosion energy is processes similar to those occurring on the Sun and other stars.
Thermonuclear reactions.
The interior of the Sun contains a gigantic amount of hydrogen, which is in a state of ultra-high compression at a temperature of approx. 15,000,000 K. At such high temperatures and plasma densities, hydrogen nuclei experience constant collisions with each other, some of which end in their fusion and ultimately the formation of heavier helium nuclei. Such reactions, called thermonuclear fusion, are accompanied by the release of enormous amounts of energy. According to the laws of physics, the energy release during thermonuclear fusion is due to the fact that during the formation of a heavier nucleus, part of the mass of the light nuclei included in its composition is converted into a colossal amount of energy. That is why the Sun, having a gigantic mass, loses approx. every day in the process of thermonuclear fusion. 100 billion tons of matter and releases energy, thanks to which life on Earth became possible.
Isotopes of hydrogen.
The hydrogen atom is the simplest of all existing atoms. It consists of one proton, which is its nucleus, around which a single electron rotates. Careful studies of water (H 2 O) have shown that it contains negligible amounts of “heavy” water containing the “heavy isotope” of hydrogen - deuterium (2 H). The deuterium nucleus consists of a proton and a neutron - a neutral particle with a mass close to a proton.
There is a third isotope of hydrogen, tritium, whose nucleus contains one proton and two neutrons. Tritium is unstable and undergoes spontaneous radioactive decay, turning into an isotope of helium. Traces of tritium have been found in the Earth's atmosphere, where it is formed as a result of the interaction of cosmic rays with gas molecules that make up the air. Tritium is produced artificially in a nuclear reactor by irradiating the lithium-6 isotope with a stream of neutrons.
Development of the hydrogen bomb.
Preliminary theoretical analysis showed that thermonuclear fusion is most easily accomplished in a mixture of deuterium and tritium. Taking this as a basis, US scientists in early 1950 began implementing a project to create a hydrogen bomb (HB). The first tests of a model nuclear device were carried out at the Enewetak test site in the spring of 1951; thermonuclear fusion was only partial. Significant success was achieved on November 1, 1951 during the testing of a massive nuclear device, the explosion power of which was 4 × 8 Mt in TNT equivalent.
The first hydrogen aerial bomb was detonated in the USSR on August 12, 1953, and on March 1, 1954, the Americans detonated a more powerful (approximately 15 Mt) aerial bomb on Bikini Atoll. Since then, both powers have carried out explosions of advanced megaton weapons.
The explosion at Bikini Atoll was accompanied by the release of a large amount of radioactive substances. Some of them fell hundreds of kilometers from the explosion site on the Japanese fishing vessel "Lucky Dragon", while others covered the island of Rongelap. Since thermonuclear fusion produces stable helium, the radioactivity from the explosion of a pure hydrogen bomb should be no more than that of an atomic detonator of a thermonuclear reaction. However, in the case under consideration, the predicted and actual radioactive fallout differed significantly in quantity and composition.
The mechanism of action of the hydrogen bomb.
The sequence of processes occurring during the explosion of a hydrogen bomb can be represented as follows. First, the thermonuclear reaction initiator charge (a small atomic bomb) located inside the HB shell explodes, resulting in a neutron flash and creating the high temperature necessary to initiate thermonuclear fusion. Neutrons bombard an insert made of lithium deuteride, a compound of deuterium and lithium (a lithium isotope with a mass number of 6 is used). Lithium-6 is split into helium and tritium under the influence of neutrons. Thus, the atomic fuse creates the materials necessary for synthesis directly in the actual bomb itself.
Then a thermonuclear reaction begins in a mixture of deuterium and tritium, the temperature inside the bomb rapidly increases, involving more and more hydrogen in the synthesis. With a further increase in temperature, a reaction between deuterium nuclei, characteristic of a pure hydrogen bomb, could begin. All reactions, of course, occur so quickly that they are perceived as instantaneous.
Fission, fusion, fission (superbomb).
In fact, in a bomb, the sequence of processes described above ends at the stage of the reaction of deuterium with tritium. Further, the bomb designers chose not to use nuclear fusion, but nuclear fission. The fusion of deuterium and tritium nuclei produces helium and fast neutrons, the energy of which is high enough to cause nuclear fission of uranium-238 (the main isotope of uranium, much cheaper than the uranium-235 used in conventional atomic bombs). Fast neutrons split the atoms of the uranium shell of the superbomb. The fission of one ton of uranium creates energy equivalent to 18 Mt. Energy goes not only to explosion and heat generation. Each uranium nucleus splits into two highly radioactive “fragments.” Fission products include 36 different chemical elements and nearly 200 radioactive isotopes. All this constitutes the radioactive fallout that accompanies superbomb explosions.
Thanks to the unique design and the described mechanism of action, weapons of this type can be made as powerful as desired. It is much cheaper than atomic bombs of the same power.
Consequences of the explosion.
Shock wave and thermal effect.
The direct (primary) impact of a superbomb explosion is threefold. The most obvious direct impact is a shock wave of enormous intensity. The strength of its impact, depending on the power of the bomb, the height of the explosion above the surface of the earth and the nature of the terrain, decreases with distance from the epicenter of the explosion. The thermal impact of an explosion is determined by the same factors, but also depends on the transparency of the air - fog sharply reduces the distance at which a thermal flash can cause serious burns.
According to calculations, during an explosion in the atmosphere of a 20-megaton bomb, people will remain alive in 50% of cases if they 1) take refuge in an underground reinforced concrete shelter at a distance of approximately 8 km from the epicenter of the explosion (E), 2) are in ordinary urban buildings at a distance of approx. . 15 km from EV, 3) found themselves in an open place at a distance of approx. 20 km from EV. In conditions of poor visibility and at a distance of at least 25 km, if the atmosphere is clear, for people in open areas, the likelihood of survival increases rapidly with distance from the epicenter; at a distance of 32 km its calculated value is more than 90%. The area over which the penetrating radiation generated during an explosion causes death is relatively small, even in the case of a high-power superbomb.
Fireball.
Depending on the composition and mass of flammable material involved in the fireball, gigantic self-sustaining firestorms can form and rage for many hours. However, the most dangerous (albeit secondary) consequence of the explosion is radioactive contamination of the environment.
Fallout.
How they are formed.
When a bomb explodes, the resulting fireball is filled with a huge amount of radioactive particles. Typically these particles are so small that once they reach the upper atmosphere, they can remain there for a long time. But if a fireball comes into contact with the surface of the Earth, it turns everything on it into hot dust and ash and draws them into a fiery tornado. In a whirlwind of flame, they mix and bind with radioactive particles. Radioactive dust, except the largest, does not settle immediately. Finer dust is carried away by the resulting cloud and gradually falls out as it moves with the wind. Directly at the site of the explosion, radioactive fallout can be extremely intense - mainly large dust settling on the ground. Hundreds of kilometers from the explosion site and at greater distances, small but still visible particles of ash fall to the ground. They often form a cover similar to fallen snow, deadly to anyone who happens to be nearby. Even smaller and invisible particles, before they settle on the ground, can wander in the atmosphere for months and even years, circling the globe many times. By the time they fall out, their radioactivity is significantly weakened. The most dangerous radiation remains strontium-90 with a half-life of 28 years. Its loss is clearly observed throughout the world. When it settles on leaves and grass, it enters food chains that include humans. As a consequence of this, noticeable, although not yet dangerous, amounts of strontium-90 have been found in the bones of residents of most countries. The accumulation of strontium-90 in human bones is very dangerous in the long term, as it leads to the formation of malignant bone tumors.
Long-term contamination of the area with radioactive fallout.
In the event of hostilities, the use of a hydrogen bomb will lead to immediate radioactive contamination of an area within a radius of approx. 100 km from the epicenter of the explosion. If a superbomb explodes, an area of tens of thousands of square kilometers will be contaminated. Such a huge area of destruction with a single bomb makes it a completely new type of weapon. Even if the superbomb does not hit the target, i.e. will not hit the object with shock-thermal effects, the penetrating radiation and radioactive fallout accompanying the explosion will make the surrounding space uninhabitable. Such precipitation can continue for many days, weeks and even months. Depending on their quantity, the intensity of radiation can reach deadly levels. A relatively small number of superbombs is enough to completely cover a large country with a layer of radioactive dust that is deadly to all living things. Thus, the creation of the superbomb marked the beginning of an era when it became possible to make entire continents uninhabitable. Even long after the cessation of direct exposure to radioactive fallout, the danger due to the high radiotoxicity of isotopes such as strontium-90 will remain. With food grown on soils contaminated with this isotope, radioactivity will enter the human body.
How Soviet physicists made the hydrogen bomb, what pros and cons this terrible weapon carried, read in the “History of Science” section.
After World War II, it was still impossible to talk about the actual onset of peace - two major world powers entered an arms race. One of the facets of this conflict was the confrontation between the USSR and the USA in the creation of nuclear weapons. In 1945, the United States, the first to enter the race behind the scenes, dropped nuclear bombs on the notorious cities of Hiroshima and Nagasaki. The Soviet Union also carried out work on creating nuclear weapons, and in 1949 they tested the first atomic bomb, the working substance of which was plutonium. Even during its development, Soviet intelligence found out that the United States had switched to developing a more powerful bomb. This prompted the USSR to start producing thermonuclear weapons.
The intelligence officers were unable to find out what results the Americans achieved, and the attempts of Soviet nuclear scientists were not successful. Therefore, it was decided to create a bomb, the explosion of which would occur due to the synthesis of light nuclei, and not the fission of heavy ones, as in an atomic bomb. In the spring of 1950, work began on creating a bomb, which later received the name RDS-6s. Among its developers was the future Nobel Peace Prize laureate Andrei Sakharov, who proposed the idea of designing a charge back in 1948, but later opposed nuclear tests.
Andrey Sakharov
Vladimir Fedorenko/Wikimedia Commons
Sakharov proposed covering a plutonium core with several layers of light and heavy elements, namely uranium and deuterium, an isotope of hydrogen. Subsequently, however, it was proposed to replace deuterium with lithium deuteride - this significantly simplified the design of the charge and its operation. An additional advantage was that lithium, after bombardment with neutrons, produces another isotope of hydrogen - tritium. When tritium reacts with deuterium, it releases much more energy. In addition, lithium also slows down neutrons better. This structure of the bomb gave it the nickname “Sloika”.
A certain challenge was that the thickness of each layer and their final quantity were also very important for a successful test. According to calculations, from 15% to 20% of the energy released during the explosion came from thermonuclear reactions, and another 75-80% from the fission of uranium-235, uranium-238 and plutonium-239 nuclei. It was also assumed that the charge power would be from 200 to 400 kilotons; the practical result was at the upper limit of the forecasts.
On Day X, August 12, 1953, the first Soviet hydrogen bomb was tested in action. The Semipalatinsk test site where the explosion occurred was located in the East Kazakhstan region. The test of the RDS-6s was preceded by an attempt in 1949 (at that time a ground explosion of a bomb with a capacity of 22.4 kilotons was carried out at the test site). Despite the isolated location of the test site, the population of the region experienced first-hand the beauty of nuclear testing. People who lived relatively close to the test site for decades, until the closure of the test site in 1991, were exposed to radiation, and areas many kilometers from the test site were contaminated with nuclear decay products.
The first Soviet hydrogen bomb RDS-6s
Wikimedia Commons
A week before the RDS-6s test, according to eyewitnesses, the military gave money and food to the families living near the test site, but there was no evacuation or information about the upcoming events. The radioactive soil was removed from the test site itself, and nearby structures and observation posts were restored. It was decided to detonate the hydrogen bomb on the surface of the earth, despite the fact that the configuration made it possible to drop it from an airplane.
Previous tests of atomic charges were strikingly different from what nuclear scientists recorded after the Sakharov puff test. The energy output of the bomb, which critics call not a thermonuclear bomb but a thermonuclear-enhanced atomic bomb, was 20 times greater than that of previous charges. This was noticeable to the naked eye in sunglasses: only dust remained from the surviving and restored buildings after the hydrogen bomb test.
Ivy Mike - the first atmospheric test of a hydrogen bomb conducted by the United States at Eniwetak Atoll on November 1, 1952.
65 years ago, the Soviet Union detonated its first thermonuclear bomb. How does this weapon work, what can it do and what can it not do? On August 12, 1953, the first “practical” thermonuclear bomb was detonated in the USSR. We will tell you about the history of its creation and figure out whether it is true that such ammunition hardly pollutes the environment, but can destroy the world.
The idea of thermonuclear weapons, where the nuclei of atoms are fused rather than split, as in an atomic bomb, appeared no later than 1941. It came to the minds of physicists Enrico Fermi and Edward Teller. Around the same time, they became involved in the Manhattan Project and helped create the bombs dropped on Hiroshima and Nagasaki. Designing a thermonuclear weapon turned out to be much more difficult.
You can roughly understand how much more complicated a thermonuclear bomb is than an atomic bomb by the fact that working nuclear power plants have long been commonplace, and working and practical thermonuclear power plants are still science fiction.
In order for atomic nuclei to fuse with each other, they must be heated to millions of degrees. The Americans patented a design for a device that would allow this to be done in 1946 (the project was unofficially called Super), but they remembered it only three years later, when the USSR successfully tested a nuclear bomb.
US President Harry Truman said that the Soviet breakthrough should be answered with “the so-called hydrogen, or superbomb.”
By 1951, the Americans assembled the device and conducted tests under the code name "George". The design was a torus - in other words, a donut - with heavy isotopes of hydrogen, deuterium and tritium. They were chosen because such nuclei are easier to merge than ordinary hydrogen nuclei. The fuse was a nuclear bomb. The explosion compressed deuterium and tritium, they merged, produced a stream of fast neutrons and ignited the uranium plate. In a conventional atomic bomb it does not fission: there are only slow neutrons, which cannot cause a stable isotope of uranium to fission. Although nuclear fusion energy accounted for approximately 10% of the total energy of the George explosion, the “ignition” of uranium-238 allowed the explosion to be twice as powerful as usual, to 225 kilotons.
Due to the additional uranium, the explosion was twice as powerful as with a conventional atomic bomb. But thermonuclear fusion accounted for only 10% of the energy released: tests showed that hydrogen nuclei were not compressed strongly enough.
Then mathematician Stanislav Ulam proposed a different approach - a two-stage nuclear fuse. His idea was to place a plutonium rod in the “hydrogen” zone of the device. The explosion of the first fuse “ignited” the plutonium, two shock waves and two streams of X-rays collided - the pressure and temperature jumped enough for thermonuclear fusion to begin. The new device was tested on the Enewetak Atoll in the Pacific Ocean in 1952 - the explosive power of the bomb was already ten megatons of TNT.
However, this device was also unsuitable for use as a military weapon.
In order for hydrogen nuclei to fuse, the distance between them must be minimal, so deuterium and tritium were cooled to a liquid state, almost to absolute zero. This required a huge cryogenic installation. The second thermonuclear device, essentially an enlarged modification of the George, weighed 70 tons - you can’t drop that from an airplane.
The USSR began developing a thermonuclear bomb later: the first scheme was proposed by Soviet developers only in 1949. It was supposed to use lithium deuteride. This is a metal, a solid substance, it does not need to be liquefied, and therefore a bulky refrigerator, as in the American version, was no longer required. Equally important, lithium-6, when bombarded with neutrons from the explosion, produced helium and tritium, which further simplifies the further fusion of nuclei.
The RDS-6s bomb was ready in 1953. Unlike American and modern thermonuclear devices, it did not contain a plutonium rod. This scheme is known as a “puff”: layers of lithium deuteride were interspersed with uranium layers. On August 12, RDS-6s was tested at the Semipalatinsk test site.
The power of the explosion was 400 kilotons of TNT - 25 times less than in the second attempt by the Americans. But the RDS-6s could be dropped from the air. The same bomb was going to be used on intercontinental ballistic missiles. And already in 1955, the USSR improved its thermonuclear brainchild, equipping it with a plutonium rod.
Today, virtually all thermonuclear devices—even North Korean ones, apparently—are a cross between early Soviet and American designs. They all use lithium deuteride as fuel and ignite it with a two-stage nuclear detonator.
As is known from leaks, even the most modern American thermonuclear warhead, the W88, is similar to the RDS-6c: layers of lithium deuteride are interspersed with uranium.
The difference is that modern thermonuclear munitions are not multi-megaton monsters like the Tsar Bomba, but systems with a yield of hundreds of kilotons, like the RDS-6s. No one has megaton warheads in their arsenals, since, militarily, a dozen less powerful warheads are more valuable than one strong one: this allows you to hit more targets.
Technicians work with an American W80 thermonuclear warhead
What a thermonuclear bomb cannot do
Hydrogen is an extremely common element; there is enough of it in the Earth’s atmosphere.
At one time it was rumored that a sufficiently powerful thermonuclear explosion could start a chain reaction and all the air on our planet would burn out. But this is a myth.
Not only gaseous, but also liquid hydrogen is not dense enough for thermonuclear fusion to begin. It needs to be compressed and heated by a nuclear explosion, preferably from different sides, as is done with a two-stage fuse. There are no such conditions in the atmosphere, so self-sustaining nuclear fusion reactions are impossible there.
This is not the only misconception about thermonuclear weapons. It is often said that an explosion is “cleaner” than a nuclear one: they say that when hydrogen nuclei fuse, there are fewer “fragments” - dangerous short-lived atomic nuclei that produce radioactive contamination - than when uranium nuclei fission.
This misconception is based on the fact that during a thermonuclear explosion, most of the energy is supposedly released due to the fusion of nuclei. This is not true. Yes, the Tsar Bomba was like that, but only because its uranium “jacket” was replaced with lead for testing. Modern two-stage fuses result in significant radioactive contamination.
The zone of possible total destruction by the Tsar Bomba, plotted on the map of Paris. The red circle is the zone of complete destruction (radius 35 km). The yellow circle is the size of the fireball (radius 3.5 km).
True, there is still a grain of truth in the myth of the “clean” bomb. Take the best American thermonuclear warhead, W88. If it explodes at the optimal height above the city, the area of severe destruction will practically coincide with the zone of radioactive damage, dangerous to life. There will be vanishingly few deaths from radiation sickness: people will die from the explosion itself, not from radiation.
Another myth says that thermonuclear weapons are capable of destroying all human civilization, and even life on Earth. This is also practically excluded. The energy of the explosion is distributed in three dimensions, therefore, with an increase in the power of the ammunition by a thousand times, the radius of destructive action increases only ten times - a megaton warhead has a radius of destruction only ten times greater than a tactical, kiloton warhead.
66 million years ago, an asteroid impact led to the extinction of most land animals and plants. The impact power was about 100 million megatons - this is 10 thousand times more than the total power of all thermonuclear arsenals of the Earth. 790 thousand years ago, an asteroid collided with the planet, the impact was a million megatons, but no traces of even moderate extinction (including our genus Homo) occurred after that. Both life in general and people are much stronger than they seem.
The truth about thermonuclear weapons is not as popular as the myths. Today it is as follows: thermonuclear arsenals of compact warheads of medium power provide a fragile strategic balance, because of which no one can freely iron other countries of the world with atomic weapons. Fear of a thermonuclear response is more than enough of a deterrent.
