Term Paper

OF

CHE-101

Topic: Chemistry of Hydrogen Bomb

Submitted by:

MANMEET SINGH Submitted to:

Roll.no- RE2801B40 Lect. Jyoti

Reg.no- 10801620

Course- B Tech. M Tech. IT

HYDROGEN BOMB

Definition:

Hydrogen bomb or H-bomb, weapon deriving a large portion of its energy from the nuclear fusion of hydrogen isotopes. In an atomic bomb, uranium or plutonium is split into lighter elements that together weigh less than the original atoms, the remainder of the mass appearing as energy. Unlike this fission bomb, the hydrogen bomb functions by the fusion, or joining together, of lighter elements into heavier elements.

The end product again weighs less than its components, the difference once more appearing as energy. Because extremely high temperatures are required in order to initiate fusion reactions, the hydrogen bomb is also known as a thermonuclear bomb.

Hydrogen bomb or H-bomb, weapon deriving a large portion of its energy from the nuclear fusion of hydrogen isotopes. In an atomic bomb, uranium or plutonium is split into lighter elements that together weigh less than the original atoms, the remainder of the mass appearing as energy.

Unlike this fission bomb, the hydrogen bomb functions by the fusion, or joining together, of lighter elements into heavier elements. The end product again weighs less than its components, the difference

once more appearing as energy. Because extremely high temperatures are required in order to initiate fusion reactions, the hydrogen bomb is also known as a thermonuclear bomb.

The first thermonuclear bomb was exploded in 1952 at Enewetak by the United States, the second in 1953 by Russia (then the USSR). Great Britain, France, and China have also exploded thermonuclear bombs, and these five nations comprise the so-called nuclear club-nations that have the capability to produce nuclear weapons and admit to maintaining an inventory of them.

The three smaller Soviet successor states that inherited nuclear arsenals (Ukraine, Kazakhstan, and Belarus) relinquished all nuclear warheads, which have been removed to Russia. Several other nations either have tested thermonuclear devices or claim to have the capability to produce them, but officially state that they do not maintain a stockpile of such weapons; among these are India, Israel, and Pakistan. South Africa's apartheid regime built six nuclear bombs but dismantled them later.

The presumable structure of a thermonuclear bomb is as follows: at its center is an atomic bomb; surrounding it is a layer of lithium deuteride (a compound of lithium and deuterium, the isotope of hydrogen with mass number 2); around it is a tamper, a thick outer layer, frequently of fissionable material, that holds the contents together in order to obtain a larger explosion. Neutrons from the atomic explosion cause the lithium to fission into helium, tritium (the isotope of hydrogen with mass number 3), and energy.

The atomic explosion also supplies the temperatures needed for the subsequent fusion of deuterium with tritium, and of tritium with tritium (50,000,000°C and 400,000,000°C, respectively). Enough neutrons are produced in the fusion reactions to produce further fission in the core and to initiate fission in the tamper.

Since the fusion reaction produces mostly neutrons and very little that is radioactive, the concept of a "clean" bomb has resulted: one having a small atomic trigger, a less fissionable tamper, and therefore less radioactive fallout. Carrying this progression further would result in the suggested neutron bomb, which would have a minimum trigger and a non-fissionable tamper; there would be blast effects and a hail of lethal neutrons but almost no radioactive fallout; this theoretically would cause minimal physical damage to buildings and equipment but kill most living things.

The theorized cobalt bomb is, on the contrary, a radioactively "dirty" bomb having a cobalt tamper. Instead of generating additional explosive force from fission of the uranium, the cobalt is transmuted into cobalt-60, which has a half-life of 5.26 years and produces energetic (and thus penetrating) gamma rays. The half-life of Co-60 is just long enough so that airborne particles will settle and coat the earth's surface before significant decay has occurred, thus making it impractical to hide in shelters. This prompted physicist Leo Szilard to call it a "doomsday device" since it was capable of wiping out life on earth.

Like other types of nuclear explosion, the explosion of a hydrogen bomb creates an extremely hot zone near its center. In this zone, because of the high temperature, nearly all of the matter present is vaporized to form a gas at extremely high pressure. A sudden overpressure, i.e., a pressure far in excess of atmospheric pressure, propagates away from the center of the explosion as a shock wave, decreasing in strength as it travels. It is this wave, containing most of the energy released-that is responsible for the major part of the destructive mechanical effects of a nuclear explosion.

The details of shock wave propagation and its effects vary depending on whether the burst is in the air, underwater, or underground.

Structure and Process:

The presumable structure of a thermonuclear bomb is as follows: at its center is an atomic bomb; surrounding it is a layer of lithium deuteride (a compound of lithium and deuterium, the isotope of hydrogen with mass number 2); around it is a tamper, a thick outer layer, frequently of fissionable material, that holds the contents together in order to obtain a larger explosion. Neutrons from the atomic explosion cause the lithium to fission into helium, tritium (the isotope of hydrogen with mass number 3), and energy.

The atomic explosion also supplies the temperatures needed for the subsequent fusion of deuterium with tritium, and of tritium with tritium (50,000,000°C and 400,000,000°C, respectively). Enough neutrons are produced in the fusion reactions to produce further fission in the core and to initiate fission in the tamper.

A device in which an uncontrolled, self-sustaining, thermonuclear fusion reaction is carried out in heavy hydrogen (deuterium or tritium) to produce an explosion. In a fusion reaction, the collision of two energy-rich nuclei results in a mutual rearrangement of their protons and neutrons to produce two or more reaction products, together with a release of energy of amount E given by A.

Einstein's formula E = mc2, where m is the mass difference between the original and produced nuclei, and c is the velocity of light.

For the hydrogen bomb reaction to become self-sustaining, a so-called critical temperature of about 3.5 × 107 K (6.3 × 107°F) must be attained with the aid of the enormous temperature created by a fission explosive. Once this temperature is achieved, the energy released in the initial reaction maintains the temperature, and the chain proceeds either until the supply of fusion-able material is exhausted or until sufficient expansion has taken place that the material is cooled below the critical temperature.

There are two ways to use fusion: boosting of fission explosive yields or generating multistage thermonuclear reactions.

In a fusion-boosted warhead, when the sphere of fissile materials is compressed (imploded) by the chemical explosion, an uncontrolled fission chain reaction begins. If there is fusionable material inside the device, thermonuclear reactions will boost the fission yield. The fusion reactions do not directly

contribute very much to the explosive energy, but instead enhance the fission rate, due to the release of a large number of additional neutrons.

Multistage thermonuclear weapons contain three physically separated components: a small fission or fusion-boosted explosive called a primary or trigger, an assembly of lithium-deuteride fusion material called the secondary, and a massive casing surrounding the primary and secondary. Explosive detonation is generated in three phases: ignition caused by the fission-explosive primary stage, coupling of x-radiation to the secondary fusion stage, and secondary-stage implosion induced by fission x-rays, which compresses the lithium-deuteride.

As neutrons from the primary traverse the compressed lithium-deuteride compound, they are absorbed in enriched lithium-6, which immediately decomposes into tritium and an alpha particle. If the tritium thus created fuses with deuterium, an energetic alpha particle and a 14-MeV neutron are released. Soon the fusion materials reach densities and temperatures where thermonuclear ignition occurs, liberating many times more energy than that which came originally from the trigger.

If the massive casing is made mostly of uranium-238 (natural or depleted uranium), neutrons from the thermonuclear reactions will cause the uranium nuclei to undergo fission, giving off still more energy. A device of this sort can be regarded as a three-stage fission-fusion-fission bomb.

The yield, or total energy, of a hydrogen bomb is expressed in megatons (1 megaton equals 1015 calories or 4.18 × 1015 joules). Typical fusion-boosted weapons yield hundreds of kilotons (tenths of megatons), and typical multistage weapons yield megatons.

Basic Principle:Since the fusion reaction produces mostly neutrons and very little that is radioactive, the concept of a “clean” bomb has resulted: one having a small atomic trigger, a less fissionable tamper, and therefore less radioactive fallout. Carrying this progression further would result in the suggested neutron bomb, which would have a minimum trigger and a non-fissionable tamper; there would be blast effects and a hail of lethal neutrons but almost no radioactive fallout; this theoretically would cause minimal physical damage to buildings and equipment but kill most living things.The theorized cobalt bomb is, on the contrary, a radioactively “dirty” bomb having a cobalt tamper. Instead of generating additional explosive force from fission of the uranium, the cobalt is transmuted into cobalt-60, which has a half-life of 5.26 years and produces energetic (and thus penetrating) gamma rays.The half-life of Co-60 is just long enough so that airborne particles will settle and coat the earth's surface before significant decay has occurred, thus making it impractical to hide in shelters. This prompted physicist Leo Szilard to call it a “doomsday device” since it was capable of wiping out life on earth.

Formation:

The Hydrogen Bomb was formed by a process called fusion. This occurs when lightweight nuclei are forced to fuse at high temperatures to form other, heavier nuclei. The temperatures need to be at millions of degrees Celsius, so the fusion occurs naturally on the sun, and other stars like it. An atomic fission bomb is used as a trigger for this reaction.

Fusion can release about 4 times more energy per unit mass than fission, and because fusion is only limited by the amount of material available, it is possible for a fusion bomb to release thousands times more power than an ordinary atom bomb. This means that the bomb that destroyed Hiroshima and Nagasaki in 1945 is not nearly the most powerful nuclear weapon made.

In some cases pure uranium is placed around the bomb, which then undergoes fission and creates a big radioactive explosion. In the H-bomb, deuterium and tritium, hydrogen's two heaviest isotopes, are fused to make a nuclei of helium and a neutron.

 The Nuclear Equation for the Fusion:

21H + 3

1H à 42He + 1

0n + energy

Nuclear reactions that occur in nuclear bombs and nuclear reactors are not chemical reactions, strictly speaking. Chemical reactions involve the formation and breaking of bonds through the sharing of electrons which are outside of the nucleus, while nuclear reactions involve the formation breaking of atomic nuclei. Keep that distinction in mind as you read this answer. Hydrogen bombs fuse two nuclei to form a new nucleus. Atomic nuclei are composed of two types of smaller parts, called protons and neutrons.

A hydrogen atom composed of one proton and one neutron are smashed into another hydrogen atom composed of one proton and two neutrons. A new atom is formed, a helium atom with two protons and two neutrons. The extra neutron flies away as well. It turns out that this new nucleus and the extra neutron have less energy than the two starting hydrogen atoms. The extra energy is released as heat and light. This amount of energy is rather large (as far as the atomic scale is concerned), and when a very large number of these nuclear reactions occur, as in a hydrogen bomb, the total amount of energy can be enormous. 

Nuclear fusion:

In nuclear physics and nuclear chemistry, nuclear fusion is the process by which multiple like-charged atomic nuclei join together to form a heavier nucleus. It is accompanied by the release or absorption of energy, which allows matter to enter a plasma state.

The fusion of two nuclei with lower mass than iron (which, along with nickel, has the largest binding energy per nucleon) generally releases energy while the fusion of nuclei heavier than iron absorbs energy; vice-versa for the reverse process, nuclear fission. In the simplest case of hydrogen fusion, two protons have to be brought close enough for their mutual electric repulsion to be overcome by the nuclear force and the subsequent release of energy.

Nuclear fusion occurs naturally in stars. Artificial fusion in human enterprises has also been achieved, although has not yet been completely controlled. Building upon the nuclear transmutation experiments of Ernest Rutherford done a few years earlier, fusion of light nuclei (hydrogen isotopes) was first observed by Mark Oliphant in 1932; the steps of the main cycle of nuclear fusion in stars were subsequently worked out by Hans Bethe throughout the remainder of that decade.

Research into fusion for military purposes began in the early 1940s as part of the Manhattan Project, but was not successful until 1952. Research into controlled fusion for civilian purposes began in the 1950s, and continues to this day.

Teller–Ulam design:

The Teller–Ulam design is a nuclear weapon design that is used in multi-megaton-range thermonuclear weapons, and is more colloquially referred to as "the secret of the hydrogen bomb." It is named after two of its chief contributors, Hungarian-born physicist Edward Teller and Polish-born mathematician Stanislaw Ulam, who developed the design in 1951. The idea is thought to pertain specifically to the use of a fission bomb "trigger" placed near an amount of fusion fuel, known as "staging", and the use of "radiation implosion" to compress the fusion fuel before igniting it. There are a number of other additions and variations to this idea posited by different sources.The first device to be based on this principle was detonated by the United States in the "Ivy Mike" nuclear test in 1952. In the Soviet Union, this design was known as Andrei Sakharov's "Third Idea." Similar devices were developed by the United Kingdom, China, and France though no specific code names are known for their designs. The most powerful thermonuclear device ever tested was the 50-megaton Soviet Tsar Bomba test.

History:

The history of nuclear weapons chronicles the development of nuclear weapons. Nuclear weapons are devices that possess enormous destructive potential derived from nuclear fission or nuclear fusion reactions. Starting with the scientific breakthroughs of the 1930s which made their development possible and continuing through the nuclear arms race and nuclear testing of the Cold War, the issues of proliferation and possible use for terrorism still remain in the early 21st century.

The first fission weapons, also known as "atomic bombs," were developed jointly by the United States, Britain and Canada during World War II in what was called the Manhattan Project. In

August 1945 two were dropped on Japan ending the Pacific War. An international team was dispatched to help work on the project. The Soviet Union started development shortly thereafter with their own atomic bomb project, and not long after that both countries developed even more powerful fusion weapons called "hydrogen bombs."

During the Cold War, the Soviet Union and United States each acquired nuclear weapons arsenals numbering in the thousands, placing many of them onto rockets which could hit targets anywhere in the world. Currently there are at least nine countries with functional nuclear weapons. A considerable amount of international negotiating has focused on the threat of nuclear warfare and the proliferation of nuclear weapons to new nations or groups. There have been (at least) four major false alarms, the most recent in 1995, that resulted in the activation of either the US's or Russia's nuclear attack early warning protocols.

Hydrogen bomb is based on the fusion of hydrogen nuclei into heavier ones by the thermonuclear reactions with release of enormous energy. As mentioned earlier the above nuclear reactions can take place only at very high temperatures. Therefore, it is necessary to have an external source of energy to provide the required high temperature. For this purpose, the atom bomb, (i.e., fission bomb) is used as a primer, which by exploding provides the high temperature necessary for successful working of hydrogen bomb (i.e., fusion bomb). In the preparation of a hydrogen bomb, a suitable quantity of deuterium or tritium or a mixture of both is enclosed in a space surrounding an ordinary atomic bomb. The first hydrogen bomb was exploded in November 1952 in Marshall Islands; in 1953 Russia exploded a powerful hydrogen bomb having power of 1 million tonnes of TNT A hydrogen bomb is far more powerful than an atom bomb. Thus if it is possible to have sufficiently high temperatures required for nuclear fusion, the deuterium present in sea (as D2O) is sufficient to provide all energy requirements of the world for millions of years. The first nuclear reactor was assembled by Fermi in 1942.

Facts:

"Edward Teller and other American scientists developed the first hydrogen bomb, which Aug. 12, 1953, followed by the United Kingdom in May 1957, China (1967), and France (1968). During the late 1980s there were some 40,000 thermonuclear devices stored in the arsenals of the world's nuclear-armed nations. This number declined during the 1990s. The massive destructive threat of these weapons has been a principle concern of the world's populace and of its statesman since the 1950s."

Considerations:

The 1963 Limited Test Ban Theory was signed by the United States, the Soviet Union and Great Britain; 113 countries have signed since then. The Comprehensive Test Ban Treaty of 1996 had the objective of banning all nuclear testing, including the testing of hydrogen bombs, on or under the Earth's surface. Of the 44 nations considered to have the capabilities to create nuclear

weapons, 26 have ratified the treaty, 15 (including the United States and Russia) have signed but not ratified it, and 3 nations (India, Pakistan and North Korea) have not signed it. When in effect, this treaty would eliminate all use of hydrogen bombs.

References:

Internet Book [R. Rhodes, Dark Sun: The Making of the Hydrogen Bomb (1995)]