United States President Harry S. Truman announces a program to develop the hydrogen bomb.
A thermonuclear weapon, fusion weapon or hydrogen bomb (H bomb) is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation atomic bombs, a more compact size, a lower mass, or a combination of these benefits. Characteristics of nuclear fusion reactions make possible the use of non-fissile depleted uranium as the weapon's main fuel, thus allowing more efficient use of scarce fissile material such as uranium-235 (235U) or plutonium-239 (239Pu). The first full-scale thermonuclear test was carried out by the United States in 1952; the concept has since been employed by most of the world's nuclear powers in the design of their weapons.Modern fusion weapons consist essentially of two main components: a nuclear fission primary stage (fueled by 235U or 239Pu) and a separate nuclear fusion secondary stage containing thermonuclear fuel: the heavy hydrogen isotopes deuterium and tritium, or in modern weapons lithium deuteride. For this reason, thermonuclear weapons are often colloquially called hydrogen bombs or H-bombs.A fusion explosion begins with the detonation of the fission primary stage. Its temperature soars past approximately 100 million kelvin, causing it to glow intensely with thermal X-rays. These X-rays flood the void (the "radiation channel" often filled with polystyrene foam) between the primary and secondary assemblies placed within an enclosure called a radiation case, which confines the X-ray energy and resists its outward pressure. The distance separating the two assemblies ensures that debris fragments from the fission primary (which move much more slowly than X-ray photons) cannot disassemble the secondary before the fusion explosion runs to completion.
The secondary fusion stageconsisting of outer pusher/tamper, fusion fuel filler and central plutonium spark plugis imploded by the X-ray energy impinging on its pusher/tamper. This compresses the entire secondary stage and drives up the density of the plutonium spark plug. The density of the plutonium fuel rises to such an extent that the spark plug is driven into a supercritical state, and it begins a nuclear fission chain reaction. The fission products of this chain reaction heat the highly compressed, and thus super dense, thermonuclear fuel surrounding the spark plug to around 300 million kelvin, igniting fusion reactions between fusion fuel nuclei. In modern weapons fueled by lithium deuteride, the fissioning plutonium spark plug also emits free neutrons which collide with lithium nuclei and supply the tritium component of the thermonuclear fuel.
The secondary's relatively massive tamper (which resists outward expansion as the explosion proceeds) also serves as a thermal barrier to keep the fusion fuel filler from becoming too hot, which would spoil the compression. If made of uranium, enriched uranium or plutonium, the tamper captures fast fusion neutrons and undergoes fission itself, increasing the overall explosive yield. Additionally, in most designs the radiation case is also constructed of a fissile material that undergoes fission driven by fast thermonuclear neutrons. Such bombs are classified as two stage weapons, and most current TellerUlam designs are such fission-fusion-fission weapons. Fast fission of the tamper and radiation case is the main contribution to the total yield and is the dominant process that produces radioactive fission product fallout.Before Ivy Mike, Operation Greenhouse of 1951 was the first American nuclear test series to test principles that led to the development of thermonuclear weapons. Sufficient fission was achieved to boost the associated fusion device, and enough was learned to achieve a full-scale device within a year. The design of all modern thermonuclear weapons in the United States is known as the TellerUlam configuration for its two chief contributors, Edward Teller and Stanislaw Ulam, who developed it in 1951 for the United States, with certain concepts developed with the contribution of physicist John von Neumann. Similar devices were developed by the Soviet Union, United Kingdom, France, and China. The thermonuclear Tsar Bomba was the most powerful bomb ever tested.As thermonuclear weapons represent the most efficient design for weapon energy yield in weapons with yields above 50 kilotons of TNT (210 TJ), virtually all the nuclear weapons of this size deployed by the five nuclear-weapon states under the Non-Proliferation Treaty today are thermonuclear weapons using the TellerUlam design.
Harry S. Truman (May 8, 1884 – December 26, 1972) was the 33rd president of the United States, serving from 1945 to 1953. A lifetime member of the Democratic Party, he previously served as a US Senator from the State of Missouri from 1935 to 1945. He was chosen as incumbent President Franklin D. Roosevelt's running mate for the 1944 presidential election. Truman was inaugurated as vice-president in 1945 and served for less than three months until President Roosevelt died. Now serving as president, Truman implemented the Marshall Plan to rebuild the economy of Western Europe and established both the Truman Doctrine and NATO to contain the expansion of communism. He proposed numerous liberal domestic reforms, but few were enacted by the Conservative Coalition that dominated the Congress.
Truman grew up in Independence, Missouri, and during World War I fought in France as a captain in the Field Artillery. Returning home, he opened a haberdashery in Kansas City, Missouri, and was elected as a judge of Jackson County in 1922. Truman was elected to the United States Senate from Missouri in 1934 and gained national prominence as chairman of the Truman Committee, which was aimed at reducing waste and inefficiency in wartime contracts. Upon assuming the presidency, he was informed about the Manhattan Project. Truman authorized the first and only use of nuclear weapons in war against the Empire of Japan. Truman's administration engaged in an internationalist foreign policy by working closely with British Prime Minister Clement Attlee. Truman staunchly denounced isolationism. He energized the New Deal coalition during the 1948 presidential election and won a surprise victory against Thomas E. Dewey that secured his own presidential term.
After the onset of the Cold War, Truman oversaw the Berlin Airlift and Marshall Plan in 1948. When North Korea invaded South Korea in 1950, he lobbied for intervention from the United Nations in the Korean War. The Truman administration deployed forces in Korean War without congressional authorization and as the war stalemated his popularity fell. Domestically, his administration successfully guided the U.S. economy through the postwar economic challenges; the expected postwar depression never happened. In 1948, he proposed the first comprehensive civil rights legislation since Reconstruction. Congress failed to pass these measures which prompted Truman to issue Executive Orders 9980 and 9981 which ordered the desegregation of the armed forces and agencies of the federal government.
Corruption in the Truman administration became a central campaign issue in the 1952 presidential election. He was eligible for reelection in 1952, but with weak polls he decided not to run. Republican Dwight D. Eisenhower attacked Truman's record and won easily. Truman went into a retirement marked by the founding of his presidential library and the publication of his memoirs. It was long thought that his retirement years were financially difficult for Truman, resulting in Congress voting a pension for former presidents, but ample evidence eventually emerged that he amassed considerable wealth, some of it while still president. When he left office, Truman's administration was heavily criticized, though critical reassessment of his presidency has improved his reputation among historians and the general population.