Absorption of ultra-intense laser pulses

We use simulations to investigate the interaction of ultra-intense laser pulses with a plasma. With an intensity greater than ${10}^{18}$ W/${\mathrm{cm}}^{2}$, these pulses have a pressure greater than ${10}^{3}$ M bar and drive the plasma relativistically. Hole boring by the light beam is a key feature of the interaction. We find substantial absorption into heated electrons with a characteristic temperature of order the pondermotive potential. Other effects include a dependence on the polarization of the incident light, strong magnetic field generation, and a period of intense instability generation in the underdense plasma.