Vlasov description of space charge inversion close to the wall in a collisionless plasma sheath at grazing incidence of the magnetic field

Abstract

We study the problem of the formation of a collisionless plasma sheath at a plasma–wall transition with grazing incidence of the magnetic field. We show that for a large ratio of the ion gyroradius to the Debye length, and below a critical angle , the electrons moving parallel to the magnetic field B can no longer follow the ions gyrating perpendicular to B. The electrons then determine the characteristic times for information propagation, with low frequency oscillations appearing in the system. The electrons can accumulate in front of the wall, resulting in a negative space charge and a reduced electric field in front of the wall. The relevant physics for this case will be studied. For angles larger than the critical angle we recover the standard sheath which is determined by the Bohm condition. We use in the presented simulations deuterium with a ratio of ion temperature to electron temperature Ti/Te = 2, and a ratio of ion gyroradius over Debye length equal to 20.