Physics of high‐intensity nanosecond electron source: Charge limit phenomenon in GaAs photocathodes
Physics of high‐intensity nanosecond electron source: Charge limit phenomenon in GaAs photocathodes
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DOI：
10.1063/1.361448
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发表时间：
1996-05
影响因子：
3.2
通讯作者：
A. Herrera‐Gomez;G. Vergara;W. Spicer
中科院分区：
文献类型：
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作者：
A. Herrera‐Gomez;G. Vergara;W. Spicer
斯坦福直线加速器中心采用砷化镓负电子亲和势阴极作为高强度短时电子源。当用高强度激光脉冲照射阴极时，产生的峰值电流极高，通常为数十安培。由于电流较大，存在一定的非线性效应。非常值得注意的是所谓的电荷限制(CL)效应，它包括对每个脉冲中的总电荷的限制；也就是说，随着光脉冲强度的增加，总的束电荷停止增加。化学发光效应与光电子从体相而在表面形成的光伏直接相关。我们讨论了使表面光电压的形成最小化的可能方法。
GaAs negative electron affinity cathodes are used as high‐intensity, short‐time electron source at the Stanford Linear Accelerator Center. When the cathodes are illuminated with high‐intensity laser pulses draw peak currents that are extremely high, typically of tens of Amperes. Because of the high currents, some nonlinear effects are present. Very noticeable is the so‐called charge limit (CL) effect, which consists of a limit on the total charge in each pulse; that is, the total bunch charge stops increasing as the light pulse intensity increases. The CL effect is directly related to a photovoltage built up in the surface as a consequence of the photoelectrons coming from the bulk. We discuss possible ways to minimize the formation of the surface photovoltage.