Analysis of magnetically immersed electron guns with non-adiabatic fields

Electron diode guns, which have strongly varying magnetic orelectric fields in a cathode-anode gap, were investigated in order to generate laminarelectron beams with highcurrent density using magnetically immersed guns. By creating a strongly varying radialelectric field in a cathode-anode gap of the electron gun, it was demonstrated that the optical properties of the gun can be significantly altered, which allows the generation of a laminar, high-currentelectron beam with relatively lowmagnetic field on thecathode. The relatively high magnetic compression of theelectron beam achieved by this method is important for producingelectron beams with highcurrent density. A similar result can be obtained by inducing a strong variation of themagnetic field in a cathode-anode gap. It was observed that creating a dip in the axialmagnetic field in the cathode-anode gap of an adiabatic electron gun has an optical effect similar to guns with strong variation of radialelectric field. By analyzing the electron trajectories angles and presenting the results in a gun performance map, different geometries of magnetically immersed electron guns withnon-adiabatic fields are compared with each other and with a more traditional adiabatic electron gun. Some advantages and limitations of guns withnon-adiabatic fields are outlined. The tests ’ results of anon-adiabatic electron gun with modifiedmagnetic field are presented.

Source: Review of Scientific Instruments - November 8, 2016 Category: Physics Authors: Alexander Pikin, James G. Alessi, Edward N. Beebe, Deepak Raparia and John Ritter Source Type: research