Fundamental research of laser wakefield acceleration driven by TW-class laser

Laser wakefield acceleration (LWFA) driven by low peak power laser system have been investigated. In this case, relatively longer laser pulse is employed for creating plasma compared to standard LWFA. The plasma wavelength and the pulse length of laser not equal, thus, wakefield not grow up resonantly.

To develop compact electron accelerator, we are studying self-modulated laser wakefield acceleration driven by 1 TW Ti:Sapphire laser with laser energy of 120 mJ and pulse width of 120 fs (full width at half maximum). Simulation results by 2-dimensional particle in cell code (2D-PIC) predicted that self-modulation occurs with electron density over 10²⁰ cm^-3 and laser spot diameter less than 10 μm. In the experiment, self-focusing have been observed, however, electron beam has not been observed. This is due to the electron density (initial gas density of gas-jet target) is not high enough for relativistic self-focusing. To make high dense gas-jet target, computational fluid dynamics (CFD) simulation is employed for calculating optimum dimension of De Laval nozzle. In this paper, experimental results will be discussed with numerical calculation results of 2D-PIC and CFD.