Parameter study of a laser-driven dielectric accelerator for radiobiology research

A parameter study for a transmission grating type laser-driven dielectric accelerator (TG-LDA) was performed. The optimum pulse laser width was concluded to be 2 ps from the restrictions on the optical damage threshold intensity and the nonlinear optical effects such as the self-phase modulation and self-focus. An irradiation intensity of 5 x 10(11) W cm(-2) (2 GV m(-1)) was suitable for a silica TG-LDA with a pulse width range from 1 ps to 10 ps. The higher order harmonics of the axial electric field distribution was capable of accelerating electrons provided that the electron speed approximately satisfies the conditions of v/c = 1/2, 1/3, or 1/4. The electrons at the initial energy of 20 kV are accelerated by an acceleration field strength of 20 MV m(-1), and the electrons were accelerated by higher fields as the speed increased. For relativistic energy electrons, the acceleration gradient was 600 MV m(-1).