Performance Improvement of a Radio Frequency Plasma Cathode Using External Magnetic Field

Abstract

With the objective of reducing the power consumption of radio frequency (RF) plasma cathodes, the effect of external magnetic field on electron emission performance of a RF plasma cathode was experimentally evaluated. In the operating range of magnetic flux density from 0 mT to 8 mT, the maximum anode current emitted from the RF plasma cathode does not depend on the magnetic field strength. In contrast, the anode voltage at which the anode current is maximized is strongly affected by the magnetic field strength. Because the plasma brightness between the orifice and the anode increases as the strength of the magnetic field increases, we consider that the change of the resistance in the plasma bridge is the reason for the reduction of the anode voltage. The electron production cost was reduced from 89 W/A to 77 W/A when the coil current for forming the external magnetic field was varied from 0 A to 0.2 A. As a result, the external magnetic field improves the power consumption for the electron extraction.