Slowing-Down Time of Fast Electrons in Plasmas via the Fokker-Planck Equation

Starting from the exact solution of the Fokker-Planck equation, the slowing-down time t_r is clearly defined and easily calculated for different types of particles. The advantage of the approach used here is that the final formula for the slowing-down time is given as a simple product between a slowly varying coefficient and a characteristic time r dependent on the initial energy and plasma parameters through a simple analytical expression. Comparison of t_r with the relaxation times previously obtained is reported.