Homogeneous cooling state of dilute granular gases of charged particles

We describe the velocity distribution function of a granular gas of electrically charged particles by means of a Sonine polynomial expansion and study the decay of its granular temperature. We find a dependence of the first non-trivial Sonine coefficient, a₂, on time through the value of temperature. In particular, we find a sudden drop of a₂ when temperature approaches a characteristic value, $T*$⁠, describing the electrostatic interaction. For lower values of T, the velocity distribution function becomes Maxwellian. The theoretical calculations agree well with numerical direct simulation Monte Carlo to validate our theory.