Laser heating and ionization of magnetically confined plasmas in the presence of strong uv and x radiation

摘要

A simple one‐dimensional model has been developed to describe the propagation of laser radiation into an underdense magnetically confined moderate‐Z plasma. A time‐dependent Coronal atomic physics code is used to calculate ionization rates and radiative losses. Radiation losses during the ionization process dominate the energy balance and set an intensity‐dependent threshold laser fluence for stripping ions such as neon down to a He‐like configuration. Attainment of the He‐like configuration is marked by a very large reduction in the soft radiation rate plus a sharp increase in the plasma temperature and laser absorption length. This is manifested by the onset of an exponentially increasing K‐shell x‐radiation rate which has been observed in a small laser‐heated neon theta pinch.