Title :
A high-DC-voltage GaAs photoemission gun: Transverse emittance and momentum spread measurements
Author :
Engwall, D. ; Bohn, Christian ; Cardman, L. ; Dunham, B. ; Kehne, D. ; Legg, R. ; Liu, H. ; Shinn, M. ; Sinclair, C.
Author_Institution :
Thomas Jefferson Nat. Accel. Facility, Newport News, VA, USA
Abstract :
We have built a high-DC-voltage photoemission gun and a diagnostic beamline permitting us to measure rms transverse emittance (ε˜x) and rms momentum spread (δ) of short-duration electron pulses produced by illuminating the cathode with light from a mode-locked, frequency-doubled Nd:YLF laser. The electron gun is a GaAs photocathode source designed to operate at 500 kV. We have measured ε˜x and δ for conditions ranging from emittance-dominated to space-charge-dominated. We report these measurements as functions of microbunch charge for different beam radii, pulse lengths, and voltages/field gradients at the cathode, and compare them with PARMELA calculations
Keywords :
III-V semiconductors; electron guns; gallium arsenide; photocathodes; 500 V; DC voltage; GaAs; GaAs photocathode; GaAs photoemission gun; PARMELA simulation; diagnostic beamline; electron gun; electron pulse; microbunch charge; momentum spread; space charge; transverse emittance; Cathodes; Current measurement; Electron beams; Electron emission; Frequency measurement; Gallium arsenide; Laser mode locking; Optical pulses; Photoelectricity; Pulse measurements;
Conference_Titel :
Particle Accelerator Conference, 1997. Proceedings of the 1997
Conference_Location :
Vancouver, BC
Print_ISBN :
0-7803-4376-X
DOI :
10.1109/PAC.1997.752734
