Determination of the ion temperature in a plasma created by optical field ionization

The evolution with time of the ion temperature of a xenon gas during and after the irradiation with a high intensity laser beam is determined. The processes taken into account are (i) direct interaction with the laser beam, (ii) binary collisions with hot electrons, (iii) contribution with the electrostatic wakefield, (iv) hydrodynamic expansion and (v) transfer of potential to kinetic energy among the plasma ions. It is shown that, because the ions are strongly coupled, the last process is by far the most efficient one. Using the One Component Plasma (OCP) model, a simple analytical formula for the ion temperature at equilibrium is obtained. Application of this work to the development of soft x-ray laser sources is stressed out.