Radiation Temperature of a Bounded Nonthermal Plasma. II. Experiment

Time‐resolved measurements of the radiation temperature $T_r$ in a weakly ionized plasma column subjected to an axial magnetic field are reported. The experiments are made at frequencies near the electron cyclotron frequency during and in the early afterglow of a pulsed argon discharge. The observed departures of $T_r$ from the kinetic temperature are used in the determination of the distribution of electron velocities $\mathrm{f(v)}$ . A comparison of the steady‐state distribution with computations based on an appropriate kinetic model shows good agreement and establishes the validity of this experimental method of measuring $\mathrm{f(v)}$ . In addition, the measured time dependence of $\mathrm{f(v)}$ allows the inference of the rates of electron‐atom cooling and electron‐electron relaxation, during the early afterglow of the pulsed discharge.