A proposed superconducting photoemission source of high brightness

Abstract

Short wavelength free-electron laser oscilla tors require electron beams o f high brightness, and, in some application, high average power. We describe the design of an electron injector for the production o f a bunched cw electrón beam o f high brightness, low energy spread, and potentially high beam power. It consists o f a superconducting reentrant cavity housing a photoemission cathode which is irradiated with short light pulses o f a mode-locked frequency doubled Nd:YAG laser. The experi mental layout o f the "superconducting photoemission source" is described together with Its components: the photocathode preparation chamber, the cavity, the cryogenic setup, and the beam analysis system. The conceptual beam parameters are discussed and first results o f an emittance calculation using a particle in cell computer code are given.

Rf and space-charge effects in laser-driven rf electron guns

“…The rf acceleration in the cavity is completely determined by the pair of equations (2) and (4). We assume that electrons leave the cathode with no kinetic energy, thus 7 = 1 at z ~ 0.…”

“…Equations (2) and (A) are often solved by neglecting the second term in Eq. (4). which represents the backwardpropagating wave' 0 '.…”

Overview of CW electron guns and LCLS-II RF gun performance

“…CW gun R&D has been pursued worldwide since the 1980s. The gun technologies include DC [5][6][7][8], Superconducting RF (SRF) [9][10][11][12][13][14][15][16][17][18], hybrid DC-SRF [19] and normalconducting (NC) RF [20,21]. This paper first surveys these technologies and then discusses the design and performance of the NC RF gun and injector at the SLAC Linac Coherent Light Source II (LCLS-II).…”

Overview on superconducting photoinjectors

“…The SRF gun concept was first proposed in 1988 [3]. Four years later, first experiments were done at the University of Wuppertal [4].…”