High quantum yield, low emittance electron sources
High quantum yield, low emittance electron sources
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发表时间：
1998-03
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通讯作者：
J. Clendenin;G. Mulhollan
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文献类型：
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作者：
J. Clendenin;G. Mulhollan
The upper limit for the rms normalized emittance is shown to be 0.3 x 10{sup -6}{pi} m per mm of radius for an electron beam extracted from a flat copper photocathode illuminated uniformly with 266-nm light. Using a III-V semiconductor such as GaAs, this limit can be reduced to 0.1 x 10{sup -6}{pi} m at room temperature and as low as 0.05 x 10{sup -6}{pi} m at cryogenic temperatures while maintaining a reasonable quantum yield. Semiconductor photocathodes in rf guns with an emittance compensation system are briefly compared with a new idea--a fast, pulsed, semiconductor photocathode closely coupled to an rf accelerating system.
