Experimental generation and characterization of uniformly filled ellipsoidal electron-beam distributions.
Experimental generation and characterization of uniformly filled ellipsoidal electron-beam distributions.
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DOI：
10.1103/physrevlett.100.244801
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发表时间：
2008-06
影响因子：
8.6
通讯作者：
Pietro Musumeci;J. Moody;R. England;J. Rosenzweig;T. Tran
中科院分区：
文献类型：
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作者：
Pietro Musumeci;J. Moody;R. England;J. Rosenzweig;T. Tran
40年来，均匀填充椭球体光束分布一直在理论上进行研究，因为它们有望在所有三个方向的坐标偏移上产生线性自场。最近，人们提出了一种产生这种分布的方案，该方案基于最初非常短的光束在其自身空间电荷力作用下的强烈纵向膨胀。在本文中，我们展示了该方案的实验演示，该方案是通过使用具有适当横向轮廓的超短激光脉冲（约35fs / ms）照射射频光电枪中的阴极而获得的。所得的4 MeV光束时空（x,t）分布使用分辨率为50 fs的射频偏转腔成像。由于光电阴极的像电荷效应，在高电荷操作下观察到椭球面轮廓的时间不对称性。这种畸变也会降低横向光束的质量。
For 40 years, uniformly filled ellipsoidal beam distributions have been studied theoretically, as they hold the promise of generating self-fields linear in the coordinate offset in all three directions. Recently, a scheme for producing such distributions, based on the strong longitudinal expansion of an initially very short beam under its own space-charge forces, has been proposed. In this Letter we present the experimental demonstration of this scheme, obtained by illuminating the cathode in a rf photogun with an ultrashort laser pulse (approximately 35 fs rms) with an appropriate transverse profile. The resulting 4 MeV beam spatiotemporal (x,t) distribution is imaged using a rf deflecting cavity with 50 fs resolution. A temporal asymmetry in the ellipsoidal profile, due to image charge effects at the photocathode, is observed at higher charge operation. This distortion is also found to degrade the transverse beam quality.