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:''This is an article about the fusion device, for other uses of the term see Zeta (disambiguation)'' ZETA, short for "Zero Energy Thermonuclear Assembly", was a major experiment in the early history of fusion power research. It was the ultimate device in a series of UK designs using the Z-pinch confinement technique, and the first large-scale fusion machine to be built. ZETA sparked an intense national rivalry with the United States pinch and stellarator programs, and as ZETA was much larger and more powerful than US machines, it was expected that it would put the UK in the lead in the fusion race. ZETA went into operation in 1957, and on each experimental run a burst of neutrons was measured. Neutrons are the most obvious results of nuclear fusion reactions, which was a positive development. Temperature measurements suggested the reactor was operating between 1 and 5 million degrees, a temperature that would produce low rates of fusion just about perfectly explaining the quantities of neutrons being seen. Early results were released in September 1957, and the following January an extensive review was released with great fanfare. Front-page articles in major newspapers announced the breakthrough as a major step on the road to unlimited power. US researchers questioned ZETA's results, which was initially dismissed by UK observers as jingoism, but over time similar US experiments demonstrated the same neutron bursts at temperatures that were clearly not high enough for fusion. Further experiments demonstrated that the temperature measurements were accounting only for the hottest portions of the fuel, and the bulk of the system was much cooler. The neutrons were later explained as the byproduct of instabilities in the fuel. The ZETA claims had to be publicly withdrawn, casting a chill over the entire fusion establishment. Most work on the z-pinch concept as a road to fusion had ended by 1961. In spite of ZETA's failure to achieve fusion, and the PR disaster that it created, the device would go on to have a long experimental lifetime and produced numerous important advances in the field. In one line of development, the use of lasers to more accurately measure the temperature was well developed at ZETA, and later used to confirm the results of the Soviet tokamak approach. In 1974, while poring over ZETA test runs it was noticed that the plasma self-stabilized ''after'' the power was turned off. This has led to the modern reversed field pinch concept, which sees continued development to this day. ==History== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ZETA (fusion reactor)」の詳細全文を読む スポンサード リンク
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