Slowing-down time of fast electrons in plasmas via the Fokker-Planck equation

In this paper, starting from the exact solution of the Fokker-Planck equation, the slowing-down time tr 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 τ dependent on the initial energy and plasma parameters through a simple analytical expression. Comparison of tr with the relaxation times previously obtained is reported