Impact of the spatial laser distribution on photocathode gun operation

被引：41

作者：

Zhou, Feng ^{[1
]}

Brachmann, Axel ^{[1
]}

Emma, Paul ^{[1
]}

Gilevich, Sasha ^{[1
]}

Huang, Zhirong ^{[1
]}

机构：

[1] SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA

来源：

PHYSICAL REVIEW SPECIAL TOPICS-ACCELERATORS AND BEAMS | 2012年 / 15卷 / 09期

关键词：

RF;

D O I：

10.1103/PhysRevSTAB.15.090701

中图分类号：

O57 [原子核物理学、高能物理学];

学科分类号：

070202 ;

摘要：

It is widely believed that a drive laser with uniform temporal and spatial laser profiles is required to generate the lowest emittance beam at the photoinjector. However, for a given 3 ps smooth-Gaussian laser temporal profile, our recent simulations indicate that a truncated-Gaussian laser spatial profile produces an electron beam with smaller emittance. The simulation results are qualitatively confirmed by later analytical calculation, and also confirmed by measurements: emittance reduction of similar to 25% was observed at the linac coherent light source (LCLS) injector with a truncated-Gaussian laser spatial profile at the nominal operating bunch charge of 150 pC. There was a significant secondary benefit-laser transmission through the iris for the truncated-Gaussian profile was about twice that compared to the nearly uniform distribution, which significantly loosens the laser power and quantum efficiency requirements for drive laser system and photocathode. Since February 9, 2012, the drive laser with the truncated-Gaussian spatial distribution has been used for LCLS routine user operations and the corresponding free electron laser power is at least the same as the one when using the nearly uniform spatial profile.

引用

页数：5

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