Number density and temperature measurements obtained using sensitive diode laser spectroscopy in an argon plasma

• Published in: Applied physics. B, Lasers and optics Vol. 82; no. 1; pp. 123 - 131
• Main Authors: BAKOWSKI, B, HANCOCK, G, PEVERALL, R, RITCHIE, G. A. D
• Format: Journal Article
• Language: English
• Published: Berlin Springer 2006
• Subjects: Biological and medical applications; Calibration; Density; Diode lasers; Discharge; Discharges for spectral sources (including inductively coupled plasma); Discharges for spectral sources (including inductively coupled plasmas); Electric discharges; Exact sciences and technology; Frequency modulation; Fundamental areas of phenomenology (including applications); Holes; Laser spectroscopy; Optical (ultraviolet, visible, infrared) measurements; Optics; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Plasma diagnostic techniques and instrumentation; Spectroscopy; Uncertainty; Temperature measurement; Temperature dependence; Frequency modulation; Inductively coupled plasma; Plasma diagnostics; Translational temperature; Laser spectroscopy; Argon; Excited states; Experimental study; Modulation spectroscopy; Laser diodes
• ISSN: 0946-2171; 1432-0649
• DOI: 10.1007/s00340-005-1961-8

The absolute concentration and translational temperature of the 2p10 and 2p7 excited states of argon have been measured in an inductively coupled plasma chamber under a variety of operating conditions using both calibrated diode laser frequency modulation spectroscopy and cavity enhanced absorption spectroscopy. Accurate lineshape analysis of frequency modulation signals has been employed to extract the desired information, and is corroborated by cavity enhanced measurements. Temperatures are found to vary linearly with pressure from ~400 K at 20 mTorr (2.7 Pa) to ~510 K at 90 mTorr (12 Pa) in a 200 W discharge while concentrations peak at 3.25X10 cm at 30 mTorr (4 Pa) (also in a 200 W discharge). The uncertainty in the recovered temperature is 7%, dominated by uncertainties in the calibration of the frequency scale.