Photocathodes for the energy recovery linacs

Abstract

This paper presents an overview of existing and emerging technologies on electron sources that can service various energy recovering linacs under consideration. Photocathodes that can deliver average currents from 1 mA to 1 A, the pros and cons associated with these cathodes are addressed. Status of emerging technologies such as secondary emitters, cesiated dispenser cathodes, field and photon assisted field emitters and super lattice photocathodes are also reviewed. r

Synthesis and x-ray characterization of sputtered bi-alkali antimonide photocathodes

“…These materials are relatively easy to grow and more resistant against contamination than other options (e.g., Cs:GaAs). [1][2][3][4] Recently they have been investigated for use as high-current, low emittance electron sources for next generation accelerator applications such as Linac Coherent Light Source II (LCLS-II). 5 These applications require high quantum efficiency (QE) and long operational lifetime, just as photodetectors do, but also require good correlation of the emitted electrons (e.g., low beam emittance).…”

Photoemission study of Cs–NF3 activated GaAs(100) negative electron affinity photocathodes

“…Recently, there is renewed interest in finding efficient photocathodes for fourth generation light sources such as free electron lasers and energy recovery linacs [5,6]. NEA photocathodes are created by depositing a very electropositive substance (e.g., cesium) and a very electronegative substance (e.g., O 2 or NF 3 ) on the surface of a III-V semiconductor to lower its vacuum level at the surface below the conduction band minimum in the bulk [1].…”

Status and Perspectives of the S-DALINAC Polarized-Electron Injector*

“…Cold surfaces in the vicinity of the cathode are expected to reduce the residual gas pressure, thereby increasing cathode lifetime. This will allow one to conduct investigations on highcurrent operation of GaAs-based spin-polarized electron sources for applications at, e.g., energyrecovery linacs [12] for positron production [13].…”