Wave generation and heating in the ST-Tokamak at the fundamental and harmonic ion cyclotron frequencies
Theoretical and experimental investigations of wave generation and heating at the fundamental and the first harmonic of the ion cyclotron frequency are reported. General theoretical considerations are followed by a description of experiments on the ST-Tokamak designed to test the feasibility of this heating scheme for providing the additional heating required for toroidal reactor operation. Two rf-coils were used in an enlarged section of the ST vacuum vessel to allow operation up to approx. 1 MW of rf-power. Wave generation efficiencies of approx. 90 percent were computed from theory and observed experimentally. The ion cyclotron (slow) wave is observed to be strongly damped, but the fast hydromagnetic wave is seen to propagate many times around the machine so that standing toroidal eigenmodes are generated. The dependence of the eigenmode resonances on the density and magnetic field agrees closely with a theory based on a cylindrical, cold-plasma model. At $omega$ = 2$omega$/sub iC/, with relatively short rf-pulses, the ion temperature approximately doubles and increases by approx. 100 eV, corresponding to a heating efficiency of approx. 20 percent. At $omega$ = $omega$/sub iC/, the ion temperature increases by only 25 percent under similar conditions. Longer rf-pulses lead to a neutral-particle influx which tends to constrict the current channel and leads to MHD- instabilities. The impurity component of this influx also leads to enhanced ion heating by decreasing the ion-electron equipartion time. The temperature increases quoted are for conditions where the effect of this neutral influx was negligible. (auth)N
- Research Organization:
- Princeton Univ., NJ
- NSA Number:
- NSA-33-005124
- OSTI ID:
- 4139562
- 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.1); CONF-741105--P1. Orig. Receipt Date: 30-JUN-76; Related Information: Plasma physics and controlled nuclear fusion research, 1974. Vol. I
- Country of Publication:
- IAEA
- Language:
- English
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