A study of hollow-cathode electron beam source surface flashover discharge and suppression

Abstract

As surface flashover discharge limits the performance of hollow-cathode electron beam sources, this work systematically investigates the surface flashover discharge in the hollow-cathode discharge process based on electrostatic field simulations. Experimental research is conducted on designing and investigating hollow cathode discharge cavities featuring structures to prevent surface flashover, both single- and multi-gap. Theoretical analysis found that the vacuum surface flashover discharge will cause an abnormal breakdown phenomenon along the wall of the insulating sleeve. The surface flashover, once formed, would develop dramatically, thus suppressing the formation of hollow-cathode discharge and becoming the main form of discharge. To eliminate the abnormal flashover breakdown, an effective suppression structure is designed regarding the triple point of the surface flashover. Through the special design, the triple points in the corners are always hidden by recessing the corner of the insulator in a notch. Moreover, corrugated structures along the insulating surface are studied, and the proper rectangular slots are designed in the inner insulating surface. The experimental results also indicate that after adopting the insulation scheme, the breakdown voltage of the discharge cavity and its working stability are greatly improved.