Plasma confinement and heating in the ELMO Bumpy Torus (EBT)
The ELMO Bumpy Torus (EBT) is a toroidal magnetic trap in which microwave heating is used to produce steady-state, high-beta plasmas. The confined plasma consists of an annular, mirror-confined, relativistic-electron component localized near the midplane of each of the 24 identical sectors of EBT; and a less energetic circulating (''toroidal'') component with more nearly isotropic pressure. The plasma is formed and heated (and maintained in steady state) by two 18-GHz klystron amplifiers producing 30 kW (cw); two travelling- wave amplifiers at 55 GHz producing 10 kW (cw); and 5 kE (cw) additional power at 10.6 GHz. Depending on ambient gas pressures, three distinct modes of plasma behaviour are observed: a cold-plasma mode (C-Mode) at high pressure; a quiet mode with significant stored energy at intermediate pressures (T-Mode); and a mode with large stored energy but high fluctuation levels at low pressure (M- Mode). In the T-Mode typical parameters are: for the toroidal component: n/sub e/ approximately 1-3 x 10$sup 12$/cm$sup 3$; T/sub e/ greater than 100 eV; T/sub i/ less than 75 eV; for the annular component: n/sub e/ approximately equal to 8 x 10$sup 10$/cm$sup 3$; T/sub e/ approximately equal to 900 keV; $beta$ approximately equal to 0.4. The observed stability is consistent with a body of theoretical results developed for EBT while the observed confinement suggests that neoclassical transport mechanisms may dominate in the T-Mode, where observed particle-replacement times are 10's of milliseconds. (auth)
- Research Organization:
- Oak Ridge National Lab., TN
- NSA Number:
- NSA-33-005156
- OSTI ID:
- 4139047
- Resource Relation:
- Conference: 5. conference on plasma physics and controlled nuclear fusion research, Tokyo, Japan, 11 Nov 1974; Other Information: See STI/PUB--381(Vol.2); CONF-741105--P2. Orig. Receipt Date: 30-JUN-76; Related Information: Plasma physics and controlled nuclear fusion research, 1974. Vol. II
- Country of Publication:
- IAEA
- Language:
- English
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