Measurement of beam currents downstream from strong electric field

A Faraday cup used for measuring the beam currents downstream from strong electric fields was designed. The strong electric field was screened by a grid. The electrons were prohibited by the positive voltage on the collector. The shape of the grid was equilateral hexagon distributed because of its lowest saturation electric field at the same grid widths and the same grid transmission rates. The beam current of a vacuum arc ion source was measured by the designed beam current measuring device and the peak value of the beam current was about 550 mA. The secondary electron yield of the Cu collector bombarded by the hybrid ion beams was calculated to be 2.0.