Coaxial Plasma Gun in the High-Density Regime and Injection into a Helical Field
A modified coaxial plasma gun in the high density regime of 20-70 mT of He was investigated experimentally and theoretically. Tile injection of the plasma torus into a drift space was studied by diamagnetical diagnostics both with and without helical bias, where the inner electrode was continued into the drift space by an insulated central conductor. Quasi-tokamak geometry is obtained (q approximate to 3;I-i approximate to 1.2; beta(p) approximate to 0.7) Mean speed of torus in drift space: 2.2 cm/mu s, which is in excellent agreement with the MIID model derived. The theoretical considerations include: (1) acceleration phase, (2) ejection, (3) injection, (4) motion in the drift space, (5) tokamak stability. Discussion of: (1) general characteristics and phenomena, (2) second half-period breakdown with autopreionization (3) prevention of transversal expansion by rarefaction waves of Mach 50 supersonic flow, (4) stability and homogeneity enhancement (factor 5), (5) agreement with model, (G) X-points and breakdown dependence, (7) velocity limitation, (8) thermal diffusion. The findings are, among other application domains, important for future designs of injectors for magnetic confinement, especially for spheromaks.
Record created on 2008-04-16, modified on 2016-08-08