Abstract

Hadron therapy requires particle beams having ~100 MeV/nucleon energy, and relative energy fluctuation below 1% [1]. Laser-driven accelerators typically produce ion beams with only tens-of-MeV/nucleon energy (the highest reported proton energy is 58 MeV [2]), and extremely wide spectra. 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 (Fig. 1a). 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) [3], and pulse energy (125 µJ) [4] in LiNbO₃ (LN) by tilted-pulse-front excitation [5]. 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.

© 2013 IEEE