Durability improvement of Cesium Telluride photocathode for an rf-gun

Abstract

A: At Waseda University, we have been studying for high quality electron beam generation using 1.6 cell Cesium Telluride (Cs-Te) photocathode rf-gun. We use photocathode as the electron source, which can generate high-quality electron beam such as low emittance, and short bunch. The performance of photocathode is evaluated mainly in terms of quantum efficiency (Q.E.) and lifetime. Cs-Te photocathode is known for high Q.E. about 10% with UV light and relatively longer lifetime among semiconductor photocathodes. Since it is a hard environment for photocathode inside the gun, it is necessary to replace the photocathode every several months. In other words, in order to achieve long-term operation of rf-gun, it is necessary to establish highly durable photocathode recipe. In this report, we report the evaluation results of Cs-Te photocathode by co-evaporation, CsBr coated photocathode performance in an rf-gun and future prospects. K: Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS)

Semiconductor photocathode's charge in a high gradient RF photoinjector

“…Modern radiofrequency (RF) photoinjectors considering as the main electron providers to FEL [1,2], colliders [3,4], synchrotron radiation facilities [5] and other state-of-art accelerators [6], use semiconductor photocathodes quite frequently [7][8][9]. Such photocathodes consisting of a thin layer (units-tens of nm) of a semiconductor with a high quantum efficiency and a metal as a substrate (figure 1) permit achieving electron bunches of a high quality.…”