Plasma channel structure organized in relativistic hole-boring by kJ/PW laser pulse*

Intense laser light can propagate beyond the critical density by making a propagation path by itself, so called “hole-boring”. The hole-boring has been discussed in relation to the fast ignition scheme of laser fusion. Theoretically, the hole-boring is described as ions reflection at the interface of pressures between laser photons and plasma ions at the pulse front in one-dimensional situation [1,2,3]. In the multi-dimensional situation, the plasma ions have a freedom to move laterally, so that they can move aside by the laser photon pressure and form the plasma channel. The formation of plasma channel depends on the ion motion in the strong magnetic fields excited at the pulse front. This motion pushes ions aside and eases the laser light moving forward; thus, it can keep the propagation speed relatively fast. In this talk, we describe the ion reflection rate in relation to the plasma channel structure. We will then speculate the plasma density in which the pulse can propagate with keeping the structure. [1] S. C. Wilks et al. Phys. Plasmas 8, 542549 (2001). [2] N. Naumova et al., Phys. Rev. Lett. 102, 025002 (2009). [3] N. Iwata et al. Nature Commun.628, 9 (2018).