PW laser intensity enhancement by a hollow solid plasma cone

High-intensity lasers are critical for exploring the laser–matter interactions. Here, we propose a scheme to enhance the light intensity of petawatt (PW) lasers. The scheme is based on a hollow solid plasma cone that is formed by the multiphoton ionization of PW lasers. The influence of the length and radius of the cone on laser intensity enhancement is systematically studied. After tight focusing by the plasma cone, the spot size is 1 × 1 μm2. Two-dimensional particle-in-cell (PIC) simulations predict an intensity enhancement of a laser pulse from 5.3×1021 to 5.5×1022 W/cm2—a ratio of 10. In addition, the focusing position of the laser can be either inside or outside the cone. Such powerful lasers can be used to increase the energy of gamma photons radiated in laser solid–target interactions. PIC simulations reveal that compared with the case without a plasma cone, both the maximum energy and yield of gamma photons are increased significantly. As plasma is robust and resistant to damage at high intensities, the plasma cone should be used as a complementary optical element to achieve higher laser intensity on existing PW laser facilities.