Application of velocity-modulation laser spectroscopy to the diagnosis of plasma

Using velocity-modulation laser spectroscopy of molecular ions, the rotational spectral intensity distribution and the line width in the (2, 3) band of CO+ comet-tail system (A2Π - X2Σ+) were measured. Not only the rotational temperature of CO+ molecular ion, but also other plasma parameters, e. g., the drift velocity and mobility of ion, the electric field strength and thermal temperature in the positive column, have been obtained. Moreover, the modulation index of velocity-modulation spectroscopy was determined to be 0.372 ± 0.119 in our experimental system.