Spatial distribution of electron cloud footprints from microchannel plates: Measurements and modeling

The measurements of the electron cloud footprints produced by a stack of microchannel plates ~MCPs! as a function of gain, MCP-to-readout distance and accelerating electric field are presented. To investigate the charge footprint variation, we introduce a ballistic model of the charge cloud propagation based on the energy and angular distribution at the MCP output. We also simulate the Coulomb repulsion in the electron cloud, which is likely to cause the experimentally observed increase in the cloud size with increasing MCP gain. Calculation results for both models are compared to the charge footprint sizes measured both in our experiments with high rear-field values ~;200–900 V/mm! and in the experiments of Edgar et al. @Rev. Sci. Instrum. 60, 3673 ~1989!# ~accelerating electric field ;30–130 V/mm!. © 1999 American Institute of Physics. @S0034-6748~99!04808-X#