ROLE OF SPACE-CHARGE IN FIELD-EMISSION CATHODES

Space charge plays an extremely important role in thermionic vacuum tu bes. Normally it can be neglected in the operation of field emitter ca thodes because the very high electric fields at the cathode negates th e formation of space charge. However at very high current densities, i t may be evident in field emission cathodes. This article explores the region where space charge affects the potential distribution in field emission cathodes of the type proposed for use in vacuum microelectro nics applications. Rectangular, cylindrical, and spherical geometries are considered.