A relativistic petawatt laser light can heat a high Z metal above keV temperatures isochorically and ionize it almost fully. Copious hard x-rays are emitted from a high-Z hot plasma, which acts as an x-ray source, while x-ray emissions serve as an energy sink for the plasma. The isochoric heating of a solid silver foil irradiated by a relativistic laser light is studied with the help of 1D and 2D particle-in-cell simulations including Coulomb collisions, ionizations, and radiation processes. We find that the radiation power from the keV silver plasma is comparable to the incident laser power when the laser intensity is less than 1019 W cm−2. Thus, the plasma formation and particle acceleration are affected by the radiation, e.g. a highly compressed shock formation. Once the laser heating is over, the silver plasma loses its energy on a timescale of picoseconds, during which hard x-rays flash. The radiation spectra of the keV silver plasma are also presented.
Fast-electron production in laser-heated plasmas