What is nuclear energy? What is a nuclear weapon?

A general term for weapons that use the energy released by self-sustaining nuclear fission or fusion reaction to produce explosions and have large-scale killing and destruction effects. Among them, fission weapons are mainly made by using the fission chain reaction principle of heavy nuclei such as uranium 235 (U) or plutonium 239 (Pu), and are usually called atomic bombs. Thermonuclear weapons or fusion weapons, usually called hydrogen bombs, are mainly made by using the thermonuclear reaction principle of light nuclei such as heavy hydrogen (H, deuterium) or overweight hydrogen (H, tritium).

The energy released by burning fossil fuels such as coal and oil comes from the combined reaction of carbon, hydrogen and oxygen. The energy released when TNT and other general chemical explosives explode comes from the decomposition reaction of compounds. In these chemical reactions, the nuclei of carbon, hydrogen, oxygen, nitrogen, etc. have not changed, but the combined state between atoms has changed. Nuclear reaction is different from chemical reaction. In nuclear fission or nuclear fusion reaction, all the nuclei involved in the reaction are transformed into other nuclei, and the atoms have also changed. So people are used to calling this kind of weapon atomic weapon. But it is essentially the reaction and transformation of the nucleus, so it is more accurate to call it a nuclear weapon.

When a nuclear weapon explodes, it releases much more energy than a conventional weapon containing only chemical explosives. For example, the energy released by 1 kg uranium fission is about 8×10/3 joules, which is about 20 million times larger than that released by 1 kg TNT explosive. Therefore, the total energy released by the explosion of nuclear weapons, that is, its power, is often expressed by the amount of TNT explosive that releases the same energy, which is called TNT equivalent. The TNT equivalent of various nuclear weapons equipped by the United States, the Soviet Union and other countries is only 1000 tons, or even lower; The big one is 6.5438+million tons, even higher.

The explosion of nuclear weapons not only releases huge energy, but also the nuclear reaction process is very rapid and can be completed in microseconds. Therefore, extremely high temperature is formed in a small area around the explosion of nuclear weapons, and the surrounding air is heated and compressed to expand rapidly, resulting in high-pressure shock waves. Nuclear explosions on the ground and in the air will also form fireballs in the surrounding air, giving off strong optical radiation. Nuclear reaction will also produce all kinds of rays and radioactive material fragments; The intense pulse rays radiated outward interact with the surrounding substances, causing the process of current growth and disappearance, resulting in electromagnetic pulses. These characteristics, which are different from the explosion of chemical explosives, make nuclear weapons have unique destructive effects such as strong shock wave, optical radiation, early nuclear radiation, radioactive contamination and nuclear electromagnetic pulse. The emergence of nuclear weapons has had a great impact on the strategy and tactics of modern warfare.

A nuclear weapon system generally consists of a nuclear warhead, a projection tool and a command and control system, and the nuclear warhead is its main component. A nuclear warhead, also known as a nuclear warhead, is often used interchangeably with the terms nuclear device and nuclear weapon. In fact, nuclear device refers to the combination of nuclear charge, other materials, initiating explosive and detonator, which can be used for nuclear testing, but usually cannot be used as a reliable weapon; Nuclear weapon refers to the whole nuclear weapon system, including nuclear warheads.

The appearance of nuclear weapons in A Brief History is the result of the great development of science and technology around the 1940s. At the beginning of 1939, German chemist O. Hahn and physical chemist F. Strassman published papers on nuclear fission of uranium atoms. Within a few weeks, scientists from many countries verified this discovery and further suggested that it was possible to create conditions for this fission reaction to proceed on its own, thus opening up a broad prospect of using this new energy to create wealth for mankind. However, like many new scientific and technological discoveries in history, the development of nuclear energy was first used for military purposes, that is, to make a powerful atomic bomb, and its process was influenced and restricted by social and political conditions at that time. Since 1939, it has become increasingly difficult for many European countries to carry out scientific research due to the expansion of the fascist German war of aggression. At the beginning of September of the same year, Danish physicist N.H.D Bohr and his collaborator J.A. Wheeler theoretically expounded the process of nuclear fission reaction, and pointed out that the best element that can cause this reaction is the isotope uranium 235. At the same time that this enlightening research result was published, Britain and France declared war on Germany. /kloc-in the summer of 0/940, the Germans occupied France. Some scientists, led by French physicist Joliot-Curie, were forced to emigrate. Britain had made plans to carry out research in this field, but due to the war, manpower and material resources were in short supply. Later, it had to cooperate with the United States and send a team of scientists headed by physicist J. chadwick to the United States to participate in the development of the atomic bomb led by theoretical physicist J. R. Oppenheimer.

In the United States, the Hungarian physicist Zilad Leo, who moved from Europe, first considered that once fascist Germany mastered the atomic bomb technology, it might bring serious consequences. After he and several other scientists who immigrated to the United States from Europe rushed to promote it,1In August, 939, physicist A. Einstein wrote to the 32nd President of the United States, F. D. Roosevelt, suggesting the development of an atomic bomb, which attracted the attention of the American government. However, at the beginning, only $6,000 was allocated. It was not until the Japanese attacked Pearl Harbor in February that 194 1 expanded its scale. By August, 1942 had developed into a huge project code-named "Manhattan Project Area", which directly employed about 600,000 people and invested more than 2 billion US dollars. By the end of World War II, three atomic bombs had been built, making the United States the first country to have an atomic bomb. To make an atomic bomb, we must not only solve a series of scientific and technical problems in weapon development, but also produce two necessary nuclear charges, uranium 235 and plutonium 239. The abundance of isotope uranium 235 in natural uranium is only 0.72%, which must be increased to more than 90% according to the design requirements of atomic bombs. At that time, after various explorations, studies and comparisons, the United States adopted three methods to produce this highly enriched uranium: electromagnetic separation, gas diffusion and thermal diffusion. Dozens of kilograms of highly enriched uranium used in the "marksmanship" atomic bomb are produced by electromagnetic separation. The cost of building an electromagnetic separation plant is about 300 million dollars (the conductive coil of the magnet is made of silver borrowed from the state treasury, and its value has not been included). Plutonium -239 is produced by neutron irradiation of uranium -238 in the reactor. Dozens of kilograms of plutonium -239 used in two "implosion" atomic bombs are produced by three graphite moderated water-cooled natural uranium reactors and their supporting chemical separation plants. The above example can illustrate the scale of the project at that time. Because America's industrial and technological facilities and construction are not directly threatened by war, and it has mastered the necessary resources and concentrated a group of domestic and foreign scientific and technological talents, so that it can quickly realize its atomic bomb development plan.

German technology was in the leading position at that time. Before 1942, Germany's level in the field of nuclear technology was roughly equal to that of the United States and Britain, and then it fell behind. The first experimental graphite reactor in the United States, led by physicist E. Fermi, was completed in194265438+February and reached the critical point; In Germany, however, heavy water reactors were used to produce plutonium-239, and a small subcritical device was not built until the beginning of 1945. In order to produce highly enriched uranium, Germany once focused on developing high-speed centrifuges, but due to air strikes and lack of electricity and materials, the progress was very slow. Secondly, a. Hitler persecuted scientists and some scientists did not cooperate, which is another reason for the slow progress in this field. More importantly, German fascist leaders are too confident that the war will be over soon, and they don't need to work hard to develop an uncertain atomic bomb. At first, they refused to support it, then it was difficult to grasp it, and the development work finally failed.

1945 After the German surrender in May, many people in the United States knew the inside story of "Manhattan Project Area", including a large number of scientists engaged in this work headed by physicist J. Franck, who opposed bombing Japanese cities with atomic bombs. At that time, the Japanese invaders were severely hit by China's long-term War of Resistance against Japanese Aggression, and their strength was greatly weakened. The attack of the United States and Britain in the Pacific almost wiped out the Japanese navy, and the sea blockade made Japan's domestic material supply extremely scarce. With Japan's defeat a foregone conclusion, the United States dropped two atomic bombs on Hiroshima and Nagasaki, Japan, only on August 6 and 9.

Before the German invasion in June, the Soviet Union was also committed to developing atomic bombs. The spontaneous fission of uranium nucleus was discovered by Soviet physicists гн flerov and κ а Petzak during this period. After the outbreak of the Great Patriotic War, the research work was interrupted until the beginning of 1943, when it was gradually resumed under the leadership of physicist kurchatov, and it was accelerated after the war. 1949 In August, the Soviet Union conducted an atomic bomb test. 1950 65438+ 10, U.S. President H.S. Truman ordered the accelerated development of hydrogen bombs. 1952, 165438+ 10, the principle test of hydrogen bomb with liquid deuterium as thermonuclear fuel was carried out in the United States, but the experimental device was very bulky and could not be used as a weapon. 1In August, 953, the Soviet Union conducted a hydrogen bomb test with solid lithium deuteride 6 as thermonuclear fuel, which made it possible to put the hydrogen bomb into practical use. The United States conducted a similar hydrogen bomb test in February 1954. Britain and France also conducted atomic and hydrogen bomb tests in the 1950s and 1960s.

When China began to build socialism in an all-round way, the basic industry developed to a certain extent, that is, it began to prepare for the development of the atomic bomb. 1959 started with serious difficulties in the national economy. In June of the same year, the Soviet government tore up the "New Defense Technology Agreement" signed by China and the Soviet Union 1957+00 in June, and then withdrew the experts. China is determined to complete this task entirely on its own. The code name of China's first atomic bomb was "596", which inspired the whole country's military and civilians to do this work together. 1964 10 10/6, the first atomic bomb test was successful. After more than two years,19665438+February 28th, the principle test of small equivalent hydrogen bomb was successful. Half a year later, in June 1967 and 17, the airdrop test of the million-ton hydrogen bomb was successful. Adhering to the principle of independence and self-reliance, China has completed the tasks of these two stages of nuclear weapons development at the fastest speed in the world.

The present situation and classification of the two atomic bombs dropped by the United States on Japan are in the form of nuclear bombs with parachutes and aircraft as vehicles. Later, with the development of weapon technology, a variety of nuclear weapon systems were formed, including ballistic nuclear missiles, cruise nuclear missiles, air defense nuclear missiles, anti-missile nuclear missiles, anti-submarine nuclear rockets, deep-water nuclear bombs, nuclear aviation bombs, nuclear shells, nuclear mines and so on. Among them, multi-warhead ballistic nuclear missiles and cruise nuclear missiles with various launch modes are the main nuclear weapons equipped by the United States and the Soviet Union.

Generally speaking, nuclear weapons are divided into two categories according to different operational purposes, namely, strategic nuclear weapons used to attack enemy strategic targets and defend their own strategic locations, and tactical nuclear weapons mainly used to attack enemy combat forces on the battlefield. The Soviet Union was also classified as a "campaign tactical nuclear weapon". The classification method of nuclear weapons is related to geographical conditions and social and political factors, and it is not very strict. Since the end of 1970s, American official documents rarely use "tactical nuclear weapons", instead of "theater nuclear weapons" and "non-strategic nuclear weapons", and medium-and long-range nuclear missiles are also classified into this category.

According to the design of nuclear warheads, the nuclear weapons that have been produced and equipped with troops mainly belong to atomic bombs and hydrogen bombs. As for the number of nuclear weapons, there are no accurate figures, and the estimates of relevant research institutions are inconsistent. Comprehensive analysis of the data in recent years shows that by the mid-1980s, the number of nuclear warheads in the United States and the Soviet Union was about 50,000, accounting for more than 95% of the world total. Its TNT equivalent is about 654.38+0.2 billion tons. During World War II, the bombs dropped by the United States in Germany and Japan totaled about 2 million tons of TNT, which was only equivalent to the equivalent of two hydrogen bombs carried by American B-52 bombers. From this rough comparison, we can see that the nuclear arsenal is huge. Comparing the quantity and equivalent of US-Soviet offensive strategic nuclear weapons (including intercontinental nuclear missiles, submarine-launched ballistic nuclear missiles, cruise nuclear missiles and strategic bombers), the United States is less than the Soviet Union in the total number of projection tools (land-based launchers, submarine-launched launch tubes and aircraft) and the total equivalent of TNT, but more than the Soviet Union in the total number of nuclear warheads. Considering that the destructive effect of nuclear explosion on the opposite target is not directly proportional to the equivalent size, another estimation method is to measure the destructive ability of a nuclear warhead by the damage area corresponding to the overpressure of a certain shock wave, that is, to take the 2/3 power of the equivalent of a nuclear warhead (calculated in millions of tons) as its "equivalent million tons equivalent" value (or to choose other powers less than 2/3 according to the characteristics, distribution and size of nuclear attack of the target). ), and then to calculate the damage ability of each powerful nuclear warhead. According to this method, the destructive power of strategic nuclear weapons of the United States and the Soviet Union is estimated. Because the number of nuclear warheads below one million tons equivalent is more than that of the Soviet Union, the gap between the two countries is not very big. However, since 1980s, with the development of Soviet nuclear weapons and multi-warhead missiles, this gap has been widening. However, the destructive ability to point (hard) targets (see point targets) plays a more important role in the projection accuracy of nuclear weapons. Because the United States has always been ahead in this respect, it is still in an advantage.

In addition to the nuclear weapons possessed by the United States, the Soviet Union, Britain and France, India also conducted a nuclear test at 1974. It is generally believed that a country with the necessary nuclear technology, a certain industrial base and economic strength is entirely possible to build an atomic bomb.

Development and test In addition to the production of uranium -235, plutonium -239 and other nuclear materials, the development of the nuclear warhead itself must be coordinated with the development procedures of the whole nuclear weapon system. The development process is roughly as follows: from the conception stage; After the pre-research or feasibility study of key technical topics and components, several design schemes including weight, size, form, power, nuclear materials, nuclear test requirements, development cycle, funds and so on are formed; After demonstration, comparison and evaluation, the design scheme is selected and the tactical and technical indicators are determined; Then carry out model research and design and various simulation tests; Process test and trial production, verify the rationality of the design through nuclear test, and finally achieve design finalization, process finalization and production approval. To accomplish these tasks, it is necessary to have a special scientific and technological team and equipped with necessary test sites, including nuclear test sites. After the weapons are delivered to the army, R&D and the production department will also provide services such as maintenance, repair and replacement of parts, make necessary improvements according to the feedback information, and be responsible for decommissioning or updating.

To design a nuclear warhead well, we must deeply understand its reaction process, its necessary conditions and various physical parameters, and master the internal relations and changing laws of many factors. Therefore, it is necessary to study a series of scientific and technical problems such as nuclear physics, neutron physics, condensed matter physics at high temperature and high pressure, supersonic fluid mechanics, detonation, computational mathematics and material science, and the development practice of nuclear warheads will in turn drive and promote the development of these disciplines. In the development process, the following links play an important role: ① The theoretical research and calculation of the reaction process should be carried out with a fast and large-capacity electronic computer, which should be as close to the actual situation as possible, so as to find the best scheme from a variety of ideas or design schemes, thus saving costs and reducing the number of nuclear tests. Since the 1940s, an important factor to promote the rapid development of electronic computer technology is precisely because of the need to develop nuclear weapons. (2) According to the scheme or index requirements, repeated simulation tests are carried out in various aspects, including chemical explosive detonation test, material and strength test, environmental condition test, control, ignition and safety test, etc. All these are necessary to achieve high reliability and safety of nuclear weapons. (3) Conduct necessary nuclear tests. No matter a large number of calculations on electronic computers or corresponding simulation tests, 100% can never be in line with the real situation of nuclear weapons program. In particular, the high temperature conditions necessary for the fusion reaction of hydrogen bombs can only be provided by fission reaction (this simulation test condition was created by using the inertial confinement technology of laser or particle beam, and it was still in the research stage until the early 1980s). Therefore, whether it can meet the design requirements must be tested by the explosion test of the nuclear device itself. Of course, the role of nuclear testing does not stop there. It is precisely because nuclear testing plays a key role in the development of nuclear weapons that the United States and the Soviet Union signed a treaty banning nuclear weapons testing in the atmosphere, outer space and underwater in 1963 to restrict other countries from developing nuclear weapons, and signed a treaty limiting the equivalent of underground nuclear tests in 1974.

Development Trend Due to the improvement of the precision of nuclear weapon projection tools, since the 1960s, the development of nuclear weapons, first of all, has greatly reduced the weight and size of nuclear warheads but still maintained a certain power, that is, the specific power (the ratio of power to weight) has been significantly improved. For example, the atomic bomb dropped by the United States in Nagasaki weighs about 4.5 tons and has a power of about 20,000 tons. At the end of 1970s, the Trident I submarine missile equipped with troops weighed about 1.32 tons, and there were ***8 sub-guided bullets, each with a power of 65,438+million tons, which was about 135 times higher than that of the atomic bomb dropped by Nagasaki. The more powerful thermonuclear weapons further enhance their power. However, it is generally believed that the development in this area may be close to the limit allowed by objective reality. Since the 1970s, the development of nuclear weapons system has focused more on improving the survivability and hit accuracy of weapons, such as American Peacekeeper /MX intercontinental missile, dwarf mini intercontinental missile, Trident II submarine missile, and Soviet SS-24 and SS-25 intercontinental missiles, which have been greatly improved and improved in these aspects.

Secondly, the reliability of nuclear warhead and its initiation control safety insurance subsystem, as well as its ability to adapt to various use and operational environments have also been improved and improved. The United States and the Soviet Union have also developed various nuclear weapons suitable for battlefield use, such as nuclear warheads with variable equivalents, nuclear warheads for various vehicles, and even envisaged the development of miniature nuclear weapons with an equivalent of only a few tons. Especially in the nuclear war environment, how to improve the anti-nuclear reinforcement ability of nuclear weapons and prevent the destruction of the enemy has attracted more attention. In addition, due to the mass production and deployment of nuclear weapons, their safety has also attracted the attention of relevant countries (see Nuclear Weapons Safety).

Another development trend of nuclear weapons is to adjust their performance through design, and to enhance or weaken some lethality and destructive power according to different needs. "Enhanced radiation weapons" and "reduced surplus radiation weapons" all belong to this category. The former increases the share of high-energy neutron radiation as much as possible, making it the main killing and damaging factor, usually called neutron bomb; The latter minimizes residual radioactivity and highlights the role of shock wave and optical radiation, but such weapons still belong to the category of thermonuclear weapons. As for the so-called "pure fusion weapon" which was widely discussed in the early 1960s, although a lot of research work has been done in the past 20 years, such as the research on the fusion reaction induced by high-power laser, which continued in the 1980s, we still can't see the realistic possibility of manufacturing this weapon.

Although the practical application of nuclear weapons is limited to the two atomic bombs when they came out, due to the development of nuclear weapons themselves and the development and application of various projectiles or vehicles related to them in the past 40 years, especially the knowledge accumulated through thousands of nuclear tests, people have a deeper understanding of their unique destructive effects (see the destructive effects of nuclear weapons) and explore possible ways of practical application. Both the United States and the Soviet Union have formulated and revised many strategies that emphasize the important role of nuclear weapons.

Where there is a spear, there is a shield. While constantly improving and improving the performance of offensive strategic nuclear weapons, the United States and the Soviet Union have been seeking means and technologies that can effectively defend against nuclear attacks. In addition to improving the anti-nuclear reinforcement capability of the nuclear weapon system and taking measures such as building a large number of basement bunkers and civil defense projects to reduce losses, the research and development of defense technologies for more effective reconnaissance, tracking, identification and interception of the other side's nuclear missiles has never stopped. In the 1960s, the United States and the Soviet Union deployed an anti-missile system to counter nuclear weapons with nuclear weapons. 1972 In May, the United States and the Soviet Union signed the Treaty on the Limitation of Anti-Ballistic Missile Systems. Soon, the United States stopped the deployment of the Guardian anti-missile system. At the beginning of 1984, the United States claimed to have formulated a "strategic defense initiative" including nuclear-activated directed energy weapons, high-energy lasers, neutral particle beams, non-nuclear interceptors and electromagnetic guns. Although the effectiveness of this defense system is still controversial, it is certain that the competition between the United States and the Soviet Union for nuclear superiority will continue.

Because of the great destructive power and unique role of nuclear weapons, it is not so much that it may change the course of future global wars, but rather that it has been and is constantly exerting an influence on the realistic international political struggle. In the late 1970s, the United States announced that it had successfully developed a neutron bomb, which was most suitable for battlefield use and should belong to the category of tactical nuclear weapons, but it was strongly opposed by almost the whole world. This example also shows the complexity of the nuclear weapons struggle.

When the first atomic bomb exploded, the China government issued a statement: China does not develop nuclear weapons because it believes in the omnipotence of nuclear weapons and wants to use them. On the contrary, China was forced to develop nuclear weapons for defense, to break the monopoly and blackmail of nuclear powers, to prevent nuclear war and to eliminate nuclear weapons. Since then, the China administration has solemnly stated many times that China will not be the first to use nuclear weapons at any time and under any circumstances, and has made many suggestions on how to prevent nuclear war. China's ideas are gradually endorsed and supported by more and more countries and people.

philology

, He, and Yang Chengzong. Principles and applications of atomic energy, Science Press, Beijing, 1965.

Translated by Thomas B. Cochrane, etc. Ke Qingshan et al., Handbook of Nuclear Weapons, People's Liberation Army Press, Beijing, 1985. (Thomas B. Cochrane, William M. Arkin and Milton M. Honegger, Nuclear Weapons Data Manual, American Nuclear Forces and Capabilities, Natural Resources Defense Council, 1984. )

Bertrand Goldschmidt, translated by Gao Qiang and Lu: Atomic Competition 1939 ~ 1966, Atomic Energy Press, Beijing, 1984. (Bertrand Goldschmidt, Atomic Competition 1936~ 1966, Fayard, 1967. )

Robert Juncker, translated by He Wei: Brighter than a thousand suns, Atomic Energy Press, Beijing, 1980. (Robert Juncker, Heller Als Tausend Sonam, 1956. )

Atomic bomb

Atomic bomb

Use that nuclear fission reaction of heavy atoms such as uranium -235 or plutonium -239,

A nuclear weapon that can release huge energy in an instant. Also known as fission bombs. The power of atomic bombs is usually several hundred to tens of thousands of tons of TNT equivalent, which is very destructive. It can be carried by different vehicles and become a nuclear missile, a nuclear aviation bomb, a nuclear mine or a nuclear shell. , can also be used as a hydrogen bomb (or trigger), to ignite light nuclear thermonuclear fusion reaction to provide the necessary energy.

The atomic bomb is mainly composed of detonation control system, high-energy explosive, reflecting layer, and nuclear components consisting of nuclear charge, neutron source and shell. The detonation control system is used for detonating high-energy explosives; High explosion is the energy that pushes and compresses the reflective layer and nuclear components. The reflective layer is made of beryllium or uranium -238. Uranium -238 can not only reflect neutrons, but also has a high density, which can slow down the expansion of nuclear charge in the process of releasing energy and maintain a chain reaction for a long time, thus improving the explosive power of atomic bombs. The nuclear charge is mainly uranium -235 or plutonium -239.

In order to trigger a chain reaction, the neutron source must provide "ignition" neutrons. Neutron sources used in nuclear explosive devices can be: deuterium-tritium reaction neutron source, polonium -2 10- beryllium source, plutonium -238 atomic bomb explosion beryllium source and californium-252 spontaneous fission source. The high temperature and high pressure produced by the atomic bomb explosion and neutrons, gamma rays and fission fragments produced by various nuclear reactions eventually form shock waves, optical radiation, early nuclear radiation, radioactive pollution and electromagnetic pulses. The atomic bomb is an outstanding example of the rapid application of the latest scientific and technological achievements to the military. 1939 10 In June, the U.S. government decided to develop atomic bombs, and 1945 built three atomic bombs. One was used for experiments and two were cast in Japan. The time when other countries exploded the first atomic bomb was: Soviet Union-1August 29th, 949; UK-1952 65438+1October 3rd; France-1960 February13; China-1964101October16; India-1974 may 18. China's first nuclear test was conducted by tower explosion, using implosion uranium bombs. May 1965 During the second nuclear test, a nuclear device was dropped by plane. 1966101October 27th, the fourth nuclear test, the nuclear warhead was carried by a missile.

Since the advent of the 1945 atomic bomb, the atomic bomb technology has been continuously developed, the volume and weight have been significantly reduced, and the tactical and technical performance has been improved day by day. The miniaturization of the atomic bomb is of great significance to improve the tactical and technical performance of nuclear weapons and to be used as the initiation device (also known as "trigger") of hydrogen bombs. In order to meet the needs of battlefield use, a variety of nuclear weapons with low equivalent and adjustable power have been developed. In order to improve the performance of the atomic bomb, an enhanced atomic bomb is developed, that is, deuterium or tritium is added to the atomic bomb, and the deuterium or tritium is ignited by the energy released by nuclear fission, so that thermonuclear reaction occurs, and the high-energy neutrons released in the reaction fission more nuclear charges, thereby improving the power. This kind of atomic bomb is different from hydrogen bomb, and the energy released by its thermonuclear charge accounts for only a small part of the total equivalent. The initiation mode of high-energy explosives and the structure of nuclear explosive devices are also constantly improved, aiming at improving the utilization efficiency of explosives and the compression degree of nuclear charges, thus improving the power and saving nuclear charges. In addition, increasing the penetration, survivability and safety of atomic bombs has been paid more and more attention.

The history of the atomic bomb

During World War II, scientist szilard mobilized the famous scientist Einstein to write to President Roosevelt, explaining the importance of developing the atomic bomb to American security.

● 194 1 12.6 (the day before the Japanese attack on Pearl Harbor), Roosevelt approved the US Scientific Research and Development Agency to fully develop the atomic bomb.

●1In August, 942, the United States formulated the "Manhattan Plan" to develop an atomic bomb.

●1In July, 943, the United States established the Atomic Bomb Research Institute.

● 1945 In March, the United States established the Atomic Energy Commission to merge secrets.

● 1945 16 On July 6th, the explosion test of the world's first atomic bomb was conducted in the Alamoco Desert in New Mexico.

1945 On August 6 and 9, the United States dropped atomic bombs on Hiroshima and Nagasaki, Japan.

● 1949, the Soviet Union successfully developed an atomic bomb. Britain and France exploded their atomic bombs at 1952 and 1960 respectively. 1964, China also had an atomic bomb.

Atomic bombs are divided into "gun type" and "shaped charge type", and nuclear weapons produce destructive power in their unique ways.

According to the different initiation mechanism of atomic bomb, it can be divided into "gun-type" atomic bomb and "convergent" atomic bomb. The "gun-type" atomic bomb places two hemispherical cracked materials with small critical volume at a certain distance, and the neutron source is located in the middle. The spherical surface of nuclear charge is coated with a layer of solid neutron reflecting material, which is used to reflect the neutrons used up prematurely, so as to improve the speed of chain reaction. Outside the neutron reflection layer are high-speed explosives, booster and detonator, and then the detonator is connected with the initiation controller. The detonation controller automatically detonates the explosive. Two hemispherical fission materials are rapidly compressed into oblate spheres under the bombardment of explosives, reaching a supercritical state. The neutron source releases a large number of neutrons to make the chain reaction proceed quickly and release huge energy in a very short time, which is the destructive atomic bomb explosion. The "convergent" atomic bomb makes ordinary high explosives into spherical devices, and nuclear charge balls smaller than the critical volume into explosive balls. Explosives detonate at the same time, rapidly compressing the nuclear charge projectile and reaching the supercritical volume, thus triggering a nuclear explosion. The structure of "convergent" atomic bomb is complex, but the utilization rate of nuclear charge is high. Modern atomic bombs combine these two initiation mechanisms to increase the utilization rate of nuclear charge to about 80%, thus gaining great destructive power.

The main ways of killing and destroying nuclear weapons are light radiation, shock wave, early nuclear radiation, electromagnetic pulse and radioactive contamination. Optical radiation is released during a nuclear explosion and travels in a straight line at a speed of 300,000 kilometers per second. The 1 atomic bomb with an equivalent of 20,000 tons will be irradiated by light three times the solar intensity/kloc-0 at a distance of 7,000 meters, with a range of 2,800 meters. Light radiation can make people blind quickly, and make skin burn and fester in a large area, and objects will burn. Shock wave is the overpressure of huge airflow produced after nuclear explosion. After the explosion of the 30,000-ton atomic bomb, the velocity of the shock wave can reach 200 m/s at a distance of 800 m from the explosion center. For a nuclear explosion with an equivalent of 20,000 tons, the overpressure value within 650 meters of the projection point of the explosion center is greater than 1000g/cm2. It can completely destroy all buildings and people in the area. Early nuclear radiation is a stream of neutrons and gamma rays released in the first few seconds of a nuclear explosion. After the 1 atomic bomb with an equivalent of 20,000 tons explodes, people within the range of 1 100 meters of the explosion center can be extremely killed. /kloc-After the 0/000t neutron bomb explodes, people within this range will die within a few weeks, and people within 200 meters will die immediately. The electric field intensity of electromagnetic pulse can reach 1 0,000 to 1 0,000 volts within several kilometers, which can not only seriously damage the components of electronic equipment, but also break down insulation, burn down circuits, cancel computer memory, and invalidate all radio command, control and communication equipment. 150 million-ton atomic bomb explosion, the damage radius can reach 190 km. Radioactive pollution is the smoke and dust falling after mushroom-shaped smoke clouds disperse, which can cause radiation or skin burns and even death to human body. 1954 On February 28th, the150,000-ton hydrogen bomb tested by the United States in Bikini Island exploded 6 hours later, and the polluted area was 257 kilometers long and 64 kilometers wide. All the creatures in this range die slowly or become disabled for life because of pollution.

Comparison of Nuclear Forces among Five Nuclear Powers

United States: 1945 The first nuclear test was successful. The number of nuclear tests exceeded 1030. It has about 12000 nuclear warheads. Missile range 13035 km.

Russia: 1949 The first nuclear test was successful. The number of nuclear tests exceeded 7 15. It has about 28,000 nuclear warheads, of which about 6,543,800,000 will be dismantled. Missile range 10943 km.

Britain: 1952 The first nuclear test was successful. * * * conducted 45 nuclear tests. Has about 400 nuclear warheads. The missile has a range of 53 10 km.

France: 1960 The first nuclear test was successful. It has about 5 10 nuclear warheads. The missile has a range of 53 10 km.

China: 1964 The first nuclear test was successful.