Improvement of the Efficiency of a Glow Discharge-Based Ion Emitter with Oscillating Electrons

摘要

Ion emission from the plasma of a low-pressure (≈5 * 10~(-2) Pa) glow discharge with electrons oscillating in a weak (≈1 mT) magnetic field is studied in relation to the cold hollow cathode geometry. A hollow conic cathode used in the electrode system of a cylindrical inverted magnetron not only improves the extraction of plasma ions to ≈20% of the discharge current but also provides the near-uniform spatial distribution of the ion emission current density. The reason is the specific oscillations of electrons accelerated in the cathode sheath. They drift in the azimuth direction along a closed orbit and simultaneously move along the magnetic field toward the emitting surface of the plasma. A plasma emitter with a current density of ≈1 mA/cm~2 over an area of ≈100 cm~2 designed for an ion source with an operating voltage of several tens of kilovolts is described.