Abstract
A compact setup with a planar-cathode and grid-anode plus free field drift distance configuration (momentatron) has provided a new way to measure the transverse momentum and, hence, the emittance of the electron beam from a photocathode. This method has been used for analysis of the transverse momentum and emittance of the photoemitted electron beam from the photocathode in a stepwise manner during the fabrication process. The errors caused by the lensing effect from opening holes of the grid anode and misalignments caused by tilting and curving have been systematically analyzed. An analytical method has been developed, and a full three-dimensional electrostatic field particle tracing simulation has been performed to validate this measurement technique. The results show that a momentatron can provide an accurate measurement of transverse momentum and emittance of the photoemitted electrons. The reasonable experimental errors that may be encountered will only have a modest (few %) effect on the emittance measurement.
Published Version
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