Start-up and ramp-up of the PLT tokamak by lower hybrid waves
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 Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- DOE Contract Number:
- AC02-76CH03073
- OSTI ID:
- 5183297
- Report Number(s):
- PPPL-2241; ON: DE85017458; TRN: 85-022893
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PLT DEVICES
LOWER HYBRID HEATING
CURRENT-DRIVE HEATING
EFFICIENCY
START-UP
WAVEGUIDES
ELECTRIC HEATING
HEATING
HIGH-FREQUENCY HEATING
JOULE HEATING
PLASMA HEATING
RESISTANCE HEATING
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
700101* - Fusion Energy- Plasma Research- Confinement
Heating
& Production