Vertical elongated 1.3:1 elliptical plasmas in which the outermost flux surfaces are magnetically expanded and diverted by external coils into the lower half of the Doublet III vacuum vessel are described. Approximately 5 cm of the nominal 45 cm plasma minor radius is diverted to the lower chamber. The diverted flux is expanded by more than a factor of ten before reaching the vessel wall. Photographic measurements show diffused hydrogen recycling light in the lower half of the vessel, with greatly reduced recycling at the normal limiters, and no evidence of localized particle flow to the vessel wall. A significant …
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General Atomic Co., San Diego, CA (USA)
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Vertical elongated 1.3:1 elliptical plasmas in which the outermost flux surfaces are magnetically expanded and diverted by external coils into the lower half of the Doublet III vacuum vessel are described. Approximately 5 cm of the nominal 45 cm plasma minor radius is diverted to the lower chamber. The diverted flux is expanded by more than a factor of ten before reaching the vessel wall. Photographic measurements show diffused hydrogen recycling light in the lower half of the vessel, with greatly reduced recycling at the normal limiters, and no evidence of localized particle flow to the vessel wall. A significant amount (approx. 50%) of the ohmic power is radiated in the expanded boundary region. Comparison of similar low density plasmas (approx. 2 x 10/sup 13/ cm/sup -3/) with and without the expanded boundary shows that (1) the expanded boundary reduces the influx of nickel and oxygen impurities by an order of magnitude, (2) the boundary also reduces the influx of injected argon and helium by a similar factor, and (3) the concentration of argon in a non-diverted plasma is reduced by a factor of 10 when the expanded boundary is turned on. The central radiated power falls by an order of magnitude, to less than 0.01 W/cm/sup 3/. Similarly, Z/sub eff/(0) drops from 3.2 to 2.1.
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Ali Mahdavi, M.; Ohyabu, N. & Baker, D.R.Properties of diverted plasmas with magnetically expanded flux surfaces,
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July 1, 1980;
San Diego, California.
(https://digital.library.unt.edu/ark:/67531/metadc1061047/:
accessed July 16, 2024),
University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu;
crediting UNT Libraries Government Documents Department.
