Tokamak Fusion Test Reactor
|Major radius||2.1–3.1 m|
|Minor Radius||0.4–0.96 m|
|Magnetic field||6.0 T (toroidal)|
|Plasma current||3.0 MA|
The Tokamak Fusion Test Reactor (TFTR) was an experimental tokamak built at Princeton Plasma Physics Laboratory (in Princeton, New Jersey) circa 1980. Following on from the PDX (Poloidal Diverter Experiment) and PLT (Princeton Large Torus) devices, it was hoped that TFTR would finally achieve fusion energy break-even. Unfortunately, the TFTR never achieved this goal. However it did produce major advances in confinement time and energy density, which ultimately contributed to the knowledge base necessary to build ITER. TFTR operated from 1982 to 1997.
In 1986 it produced the first 'supershots' which produced many more fusion neutrons.
In experiments conducted during July 1986, one of the world's biggest Tokamaks achieved a plasma temperature of 200 million kelvin (200 MK).This temperature, achieved by the Tokamak Fusion Test Reactor (TFTR) at the Princeton (N.J.) Plasma Physics Laboratory, is the highest ever reached in a laboratory. The temperature is 10 times greater than the center of the sun, but more important, it is more than enough for breakeven, which is the point where fusions produce as much energy needed to be expended to ignite them. Besides temperature, break-even requires another criterion: the product of plasma density and confinement time, usually called the Lawson criterion. In April 1986, TFTR experiments at lower temperatures produced a Lawson criterion of 1.5 x 10[sup14] seconds per cubic centimeter, which is close to the goal for a practical reactor and five to seven times what is needed for break-even. However, the 200-MK experiments had a Lawson criterion of 10[sup13], two or three times too small for break-even. The next step for the physicists working at TFTR was to put the high values together and get break-even. Donald Grove, TFTR project manager, said they expected to achieve that in 1987 using the hydrogen isotope deuterium, with which they had been working with so far. Then they intended to introduce another hydrogen isotope, tritium. Deuterium-tritium fusion, which most controlled fusion experiments today are trying to achieve, produces energetic neutrons, from which energy can easily be harvested and converted to useful things like steam or electric power. They hoped to achieve deuterium-tritium break-even in 1989.
In December, 1993, TFTR became the world's first magnetic fusion device to perform extensive experiments with plasmas composed of 50/50 deuterium/tritium.In 1994 it produced a then world-record 10.7 megawatts of fusion power from a plasma composed of equal parts of deuterium and tritium (exceeded at JET in the UK, which generated 16MW for 22MW input in 1997, which is the current record). The two experiments had emphasized the alpha particles produced in the deuterium-tritium reactions. It was followed by the NSTX spherical tokamak.
- Fusion. Robin Herman. 1990. ISBN 0-521-38373-0
- A Plasma 10 Times as hot as the Sun. Dietrick E. Thomsen. 1996. ISSN 0036-8423
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