The calculation of the electron distribution function following tunnellingionization using a Fokker-Planck method

The breakdown of gases by high-intensity radiation is well established. The electrons are released with a characteristic non-Maxwellian energy distrib ution, which depends on the nature of the ionization process. Following ion ization the distribution is further modified by collisions, which both rela x it towards the equilibrium Maxwellian, and heat it through inverse bremss trahlung. This phenomenon is of considerable interest for the possible gene ration of x-ray laser radiation. We examine algorithms for the rapid calcul ation of this behaviour based on the relaxation of an isotropic electron ve locity distribution due to electron-electron and electron-ion collisions fo llowing ionization by light of arbitrary polarization. The treatment of ele ctron-ion collisions is very similar to earlier work on inverse bremsstrahl ung absorption. The application to both recombination and collisional x-ray lasers is discussed through the examination of typical examples.