Effect of discharge tube temperature on N2(A3Σu+) and N(4So) densities in remote nitrogen plasma

We examined the effect of the discharge tube temperature on the densities of N-2(A(3)Sigma(+)(u)) and N(S-4(o)) in microwave-excited remote nitrogen plasma. The density of N(S-4(o)) and the rotational temperature of N-2(C-3 Pi(u)) were constant against the discharge tube temperature between 30 degrees C and 400 degrees C, whereas we observed the decrease in the N-2(A(3)Sigma(+)(u)) density. In addition, we observed the decreases in the density and the vibrational temperature of N-2(C-3 Pi(u)) with the discharge tube temperature. The experimental results indicated the decrease in the production rates of the electronic excited states in the spatial afterglow, which may be caused by the lower density of vibrational excited states of molecular nitrogen in the heated discharge tube. (c) 2020 The Japan Society of Applied Physics