Browsing by Subject "Magnetohydrodynamic waves"
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Item Current drive by asymmetrical heating in a toroidal plasma(Texas Tech University, 1986-08) Gahl, John MichelThis report describes the first experimental observation of current generation by asymmetrical heating of ions. A unidirectional fast Alfven wave launched by a slow wave antenna inside the Texas Tech Tokamak. Asymmetrically heated the ions. Measurements of the asymmetry of the toroidal plasma current with probes at the top and bottom of the toroidal plasma column confirmed the current generation indirectly. Current generation, obtained in a one-species, hydrogen plasma, is a phenomenon which had not been predicted previously. Calculations of the dispersion relation for the fast Alfven wave near the fundamental cyclotron resonance in a one-species, hydrogen plasma, using warm plasma theory, support the experimental results.Item Fast wave propagation and minority ion heating current drive in a two-ion species tokamak plasma(Texas Tech University, 1986-08) Wong, Kin-luLocal cavity resonances of fast waves in a two-ion species tokamak plasma and current generation due to the asymmetric cyclotron heating of minority ions by fast waves have been investigated. The experimental results demonstrate the existence of a local cavity resonance for fast waves propagating in a deuterium tokamak plasma with a low concentration (5%) of hydrogen minority ions. The local resonance cavity for the fast waves is formed by the hybrid cutoff layer and the outer wall* Current generation by asymmetric minority heating with no net momentum injection into the plasma is studied numerically by solving the Fokker-Planck equation in which the quasi-linear diffusion term for cyclotron absorption is added to the Coulomb collision terms. The results show that the current drive efficiency is better in a hydrogen-deuterium plasma than in a helium^3-deuterium plasma. The applicability of the minority ion heating current drive scheme in a hydrogen tokamak plasma with unavoidable impurity ions as the minority ions is investigated. The practicality of this current drive process for fusion reactors is also discussed.