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Title: Measurements of population densities of metastable and resonant levels of argon using laser induced fluorescence

We present a new approach to measure population densities of Ar I metastable and resonant excited states in low temperature Ar plasmas at pressures higher than 1 Torr. This approach combines the time resolved laser induced fluorescence technique with the kinetic model of Ar. The kinetic model of Ar is based on calculating the population rates of metastable and resonant levels by including contributions from the processes that affect population densities of Ar I excited states. In particular, we included collisional quenching processes between atoms in the ground state and excited states, since we are investigating plasma at higher pressures. We also determined time resolved population densities of Ar I 2 p excited states by employing optical emission spectroscopy technique. Time resolved Ar I excited state populations are presented for the case of the post-discharge of the supersonic flowing microwave discharge at pressures of 1.7 and 2.3 Torr. The experimental set-up consists of a pulsed tunable dye laser operating in the near infrared region and a cylindrical resonance cavity operating in TE{sub 111} mode at 2.45 GHz. Results show that time resolved population densities of Ar I metastable and resonant states oscillate with twice the frequency of the discharge.
Authors:
; ; ; ;  [1]
  1. Center for Accelerator Science, Department of Physics, Old Dominion University, Norfolk, Virginia 23529 (United States)
Publication Date:
OSTI Identifier:
22412814
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ARGON; ATOMS; CAVITY RESONATORS; DYE LASERS; EMISSION SPECTROSCOPY; EXCITED STATES; FLUORESCENCE; GHZ RANGE; GROUND STATES; HIGH-FREQUENCY DISCHARGES; METASTABLE STATES; PLASMA; PLASMA PRESSURE; POPULATION DENSITY; SUPERSONIC FLOW; TIME RESOLUTION