Time-resolved temperature in an argon theta-pinch by line ratio methods

Pulsed inductive argon plasma in an 80 J, 15 kV, 490 kHz theta-pinch is interrogated using spectroscopic methods. Time-resolved electron temperature is obtained with line intensity ratios coupled with corona and collisional-radiative models. Neutral excited state argon transitions from the 2p to 1s sub-shells were utilized. Backfill pressures of 50 and 100 mTorr are of primary focus here. Time-resolved electron temperature estimates range from 2.4 to 8.6 eV for the steady-state corona model analysis while the collisional-radiative analysis predicts temperature in excess of 80 eV. Electron temperature can be seen to ramp up between approximately the first and third zero-crossings of the oscillating discharge current. Analysis of long exposures reveal substantial second order diffracted spectra. Low spectral signal quality for short exposures of 0.25 μs yield poor time-resolved spectra and ultimately elucidate the fundamental time-resolution limitation of this experimental test article.