Self-focused electron beams produced by pyroelectric crystals on heating or cooling in dilute gases

Self-focusing, spatially stable, electron beams are produced by cylindrical pyroelectric crystals such as LiNbO3 in dilute gases on cooling provided that heating is done from the +z base. Beam energies up to 170 keV have been observed. A 4 mm diameter x 10 mm crystal heated to 160 degreesC gives rise to spatially stable beams with a focal length of 22 mm and a 1 mm spot size. Here we present photographic as well as electronic proof of the existence of these electron beams. (C) 2001 American Institute of Physics.