Evanescent-wave proton post-accelerator driven by intense THz pulses

Here, a compact solution is proposed for post-acceleration and monochromatization of particles leaving the laser-driven accelerator. The proposed method relies on the evanescent field of intense THz pulses undergoing total internal reflection at symmetrically arranged dielectric-vacuum interfaces. THz pulses in the 0.1-1 THz frequency range are promising for this application, due to their advantageous wavelength, and to the fact that they can be generated with extremely high electric field strength (>1 MV/cm), and pulse energy (125 μJ) in LiNbO₃ (LN) by tilted-pulse-front excitation. Choosing LN as the dielectric material of the evanescent accelerator has the important advantage that it can function also as THz source leading to a very compact setup.