High voltage DC gun for high intensity polarized electron source

TL;DR

This paper presents a high voltage DC gun designed for high intensity polarized electron sources, demonstrating high bunch charge, stability, and enhanced lifetime, advancing future nuclear physics accelerator technology.

Contribution

The paper introduces a novel high voltage DC gun with large cathode size, high gradient operation, and lifetime enhancement techniques for polarized electron sources.

Findings

Achieved up to 16 nC bunch charge at 300 kV

Demonstrated stable operation and long cathode lifetime

Implemented cathode cooling for high current applications

Abstract

The high intensity polarized electron source is a critical component for future nuclear physics facilities. The Electron Ion Collider (EIC) requires a polarized electron gun with higher voltage and higher bunch charge compared to any existing polarized electron source. At Brookhaven National Laboratory, we have built an inverted high voltage direct current (HVDC) photoemission gun with a large cathode size. We report on the performances of GaAs photocathodes in a high gradient with up to a 16 nC bunch charge. The measurements were performed at a stable operating gap voltage of 300 kV - demonstrating outstanding lifetime, and robustness. We observed obvious lifetime enhancement by biasing the anode. The gun also integrated a cathode cooling system for potential application on high current electron sources. The various novel features implemented and demonstrated in this polarized HVDC gun open the door towards future high intensity-high average current electron accelerator facilities.