Tunneling ionization bunch length monitor for the ultrarelativistic compressed electron beams

The electric field intensity of the compressed ultrarelativistic electron beams is approaching GV/m levels, which is sufficient to cause observable tunneling effect in the low band gap materials. In this article the tunneling ionization rate is estimated for the experimentally available electron beam parameters, and a proposed proof of principle experiment is outlined. Tunneling effect has exponential dependence on the electric field strength; thus being very sensitive to the electron beam peak current. This nonlinear dependence opens up a possibility to construct inexpensive, single shot and nondestructive peak current diagnostics for the ultrarelativistic compressed electron beams.