Start-up and ramp-up of the PLT tokamak by lower hybrid waves

Technical Report · Thu Aug 01 04:00:00 EDT 1985

DOI:https://doi.org/10.2172/5183297· OSTI ID:5183297

Jobes, F C; Bernabei, S; Chu, T K; Fisch, N J; Hooke, W M; Karney, C F.F.; Merservey, E B; Motley, R W; Stevens, J E; von Goeler, S

Lower hybrid waves have been used on the PLT tokamak both to start the plasma current and to ramp it up from pre-existing levels. The waves, at 800 MHz, were launched from a 6-waveguide grill. The phasing between adjacent guides could be selected electronically, and thus the launched spectrum could be set and changed at will. For start-up, the waveguide phase difference was initially set at 0/sup 0/ in order to create a plasma, then switched to 90/sup 0/ to drive the current. Over 100 kA of plasma current, at a density of 0.5 to 1 x 10/sup 12/ cm/sup -3/, was generated in this manner. Ramp-up experiments were performed under a wide variety of conditions. The most efficient ramp-up was found at the lowest plasma densities and with the fastest launched spectrum (n/sub e/ approx. 2 x 10/sup 12/ cm/sup -3/, N/sub parallel/ approx. 1.6 peak); approx.20% of the launched RF power was converted to (increased) poloidal field energy. All of the ramp-up results are in excellent agreement with a theory which determines the efficiency of ramp-up from the consideration of the relative energy losses of the superthermal current-carrying electrons to collisions and to the opposing inductive E-field.

• Research Organization: Princeton Univ., NJ (USA). Plasma Physics Lab.
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 5183297
• Report Number(s): PPPL-2241; ON: DE85017458
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
CURRENT-DRIVE HEATING
EFFICIENCY
ELECTRIC HEATING
HEATING
HIGH-FREQUENCY HEATING
JOULE HEATING
LOWER HYBRID HEATING
PLASMA HEATING
PLT DEVICES
RESISTANCE HEATING
START-UP
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
WAVEGUIDES