Effects of beam perveance on the performance characteristics of the electrically electron-suppressed beam direct converter with secondary electron suppressor grids

To determine the effects of beam perveance on the performance characteristics of a beam direct energy converter (BDC) with secondary electron suppressor grids and to examine the validity of the BDC design, helium beams of various energies and currents (from 15 keV, 60 mA up to 20 keV, 250 mA) were injected to the BDC. Current recovery efficiency is found to have a maximum near the designed perveance. A similar dependence occurs for the 15- and 20-keV beams when collectors are at a grounded potential. With an increase of collector potentials, there seems to be an increase in the efficiency between 15 and 20 keV. Net energy recovery efficiencies in the experiments have shown that they are almost constant in the region below the design perveance and then begin to decrease with an increase of beam perveance. It is found that the beam perveance, rather than beam energy and current, constitutes a good parameter in evaluating the performance characteristic of the BDC. The design of the BDC is also found to be suitable