Efficient temporal shaping of electron distributions for high-brightness photoemission electron guns
Efficient temporal shaping of electron distributions for high-brightness photoemission electron guns
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DOI：
10.1103/physrevstab.11.040702
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发表时间：
2008-04-01
影响因子：
--
通讯作者：
Sinclair, Charles K.
中科院分区：
文献类型：
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作者：
Bazarov, Ivan V.;Ouzounov, Dimitre G.;Sinclair, Charles K.
为了实现最低发射度的电子束从光电发射电子枪，它是必不可少的，以限制不相关的发射度增长，由于空间电荷力作用在聚束附近的光阴极通过适当的时间整形的光脉冲照射光阴极。我们提出了测量的时间轮廓的电子束从体晶体GaAs光电阴极照射520 nm波长的脉冲从倍频Yb光纤激光器。横向偏转射频腔被用来进行这些测量。测得的激光脉冲的时间分布和相应的电子束的时间分布具有约30 ps的半高宽持续时间，上升和下降时间为几ps。520 nm光脉冲照射的GaAs是一个即时发射器在我们的测量不确定度类似于1 ps rms。结合负电子亲和势光电阴极的低热发射率，GaAs是非常适合用于高亮度光电注入器的光电阴极。我们还报告测量的光电发射响应时间为砷化镓磷，这表明了强烈的依赖于光电阴极的量子效率。
To achieve the lowest emittance electron bunches from photoemission electron guns, it is essential to limit the uncorrelated emittance growth due to space charge forces acting on the bunch in the vicinity of the photocathode through appropriate temporal shaping of the optical pulses illuminating the photocathode. We present measurements of the temporal profile of electron bunches from a bulk crystal GaAs photocathode illuminated with 520 nm wavelength pulses from a frequency-doubled Yb-fiber laser. A transverse deflecting rf cavity was used to make these measurements. The measured laser pulse temporal profile and the corresponding electron beam temporal profile have about 30 ps FWHM duration, with rise and fall times of a few ps. GaAs illuminated by 520 nm optical pulses is a prompt emitter within our measurement uncertainty of similar to 1 ps rms. Combined with the low thermal emittance of negative electron affinity photocathodes, GaAs is a very suitable photocathode for high-brightness photoinjectors. We also report measurements of the photoemission response time for GaAsP, which show a strong dependence on the quantum efficiency of the photocathode.