On the role of electrostatic and magnetic electron confinement in hollow cathode glow dis-charge in no uniform magnetic field

摘要

Glow discharge with electron confinement in an electrostatic trap has been studied, the trap being formed by a cylindrical hollow cathode as well as a flat target on its bottom and a grid covering its output aperture both being negative to the cathode. At the gas pressure 0.2-0.4 Pa the part δ = 0.13 of sputtering the target ions from the whole number of ions emitted by homogeneous discharge plasma corresponds to the ratio of the target surface area to the total surface area of the cathode, grid and target. Influence on the discharge of a nonuniform magnetic field with lines crossing the target center, where magnetic induction reaches 35 mT, as well as the grid, the hollow cathode and the target periphery, where the field lines are arc-shaped, depends on the magnetic induction Bo on the target edge. At Bo = 1 mT contribution to the gas ionization of electrons emitted by the target periphery and azimuthally drifting in the arc-shaped field is insignificant. Nevertheless, due to ionization by electrons emitted by the cathode and forced by the magnetic field to come to the target more frequently 8 grows 2 times and the plasma density near the target becomes more than 2 times higher than near the grid. At Bo = 6 mT contribution to the gas ionization near the target of electrons emitted by its surface grows up and 8 increases more 2 times. At any voltage between the cathode and the target from zero to 3 kV the current in the target circuit falls down to zero with decreasing to zero the voltage between the anode and the cathode.