Single shot cathode transverse momentum imaging in high brightness photoinjectors

Abstract

In state of the art photoinjector electron sources, thermal emittance from photoemission dominates the final injector emittance. Therefore, low thermal emittance cathode developments and diagnostics are very important. Conventional thermal emittance measurements for the high gradient gun are time-consuming and thus thermal emittance is not measured as frequently as quantum efficiency during the lifetime of photocathodes, although both are important properties for the photoinjector optimizations. In this paper, a single shot measurement of photoemission transverse momentum, i.e., thermal emittance per rms laser spot size, is proposed for photocathode RF guns. By tuning the gun solenoid focusing, the electrons transverse momenta at the cathode are imaged to a downstream screen, which enables a single shot measurement of both the rms value and the detailed spectra of the photoelectrons transverse momenta. Both simulations and proof of principle experiments are reported.

arXiv comment9 pages, 15 figures

References in corpus (5)

• Demonstration of Cathode Emittance Dominated High Bunch Charge Beams in a DC gun-based Photoinjector
• Quantum efficiency of technical metal photocathodes under laser irradiation of various wavelength
• Exact Cancellation of Emittance Due to Coupled Transverse Dynamics in Solenoids and RF Couplers
• Overestimation of thermal emittance in solenoid scans due to coupled transverse motion
• Experimental demonstration of the correction of coupled transverse dynamics aberration in an rf photoinjector

Cited by in corpus (2)

• Analysis of photoinjector transverse phase space in action and phase coordinates
• Eliminating uncertainty of thermal emittance measurement in solenoid scans due to rf and solenoid fields overlap