Ion acceleration in a quasi-neutral current sheet

This paper reports on results derived from a study of proton acceleration processes in a neutral sheet with a small transverse component of the magnetic field on a theta-pinch device. Effects of ion reflection, resonance acceleration during an interaction of particles with a macroscopic potential jump in the sheet ( V_p × B - acceleration), preacceleration in the plasma-turbulence region, and particle fluxes along a neutral line were revealed. It is found that the acceleration is inhomogeneous at the O- and X-points and is anisotropic with respect to the direction of current in the sheet. Results of laboratory experiments are compared with measurements in the geomagnetic tail, and the usefulness of such a comparison is pointed out.