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arXiv · 2002.06837

Single shot cathode transverse momentum imaging in high brightness photoinjectors

Peng-Wei Huang·Houjun Qian·Ye Chen·Daniele Filippetto·Matthias Gross·Igor Isaev·Christian Koschitzki·Mikhail Krasilnikov·Shankar Lal·Xiangkun Li·Osip Lishilin·David Melkumyan·Raffael Niemczyk·Anne Oppelt·Fernando Sannibale·Hamed Shaker·Guan Shu·Frank Stephan·Chuanxiang Tang·Grygorii Vashchenko·Weishi Wan
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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.

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Peng-Wei Huang, Houjun Qian, Ye Chen, Daniele Filippetto, Matthias Gross, Igor Isaev, Christian Koschitzki, Mikhail Krasilnikov, Shankar Lal, Xiangkun Li, Osip Lishilin, David Melkumyan, Raffael Niemczyk, Anne Oppelt, Fernando Sannibale, Hamed Shaker, Guan Shu, Frank Stephan, Chuanxiang Tang, Grygorii Vashchenko, Weishi Wan. 2020-02-17. Single shot cathode transverse momentum imaging in high brightness photoinjectors. https://doi.org/10.1103/physrevaccelbeams.23.043401

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