Generation of self-focused electron beam by pyroelectric/photogalvanic crystal accelerators

We have observed generation of the electron beam by the pyroelectric crystal placed in the vacuum chamber. Different pyroelctric materials, Fe-doped LiNbO3 and L-alanine doped TGS crystals, were tested. Crystals of L-alanine doped TGS (LATGS) were grown by evaporation of the solution with 10% initial concentration of L-alanine under T=45 degrees C (somewhat below phase transition temperature T-C = 49.9 degrees C). In this case crystallization proceeds immediately in the polar phase Heating/cooling cycles of the crystals in the vacuum (P similar to 1-5 mTorr) produce uncompensated surface charges and strong electric field (similar to 100kV/cm) on the polar crystal faces. These fringing fields ionize ambient gas and accelerate electrons to high energies (similar to 100 KeV). For photosensitive LiNbO3 crystal electrical charging and generation of electrons may be done by laser illumination, via photogalvanic effect. These generated electrons can be detected by the fluorescent ZnS screen or by the X-rays produced by placing copper plate in the electron beam. Model that explains and figures that depict the self-focusing of the electron beam is presented.