Time-resolved ion density determination by electrical current measurements in an atmospheric-pressure argon plasma
Leibniz Institute for Plasma Science and Technology (INP Greifswald) - Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany
Received: 7 November 2013
Accepted: 13 January 2014
High-resolution current signal measurements of a self-pulsing transient spark discharge revealed oscillations in the pulse decay phase. These oscillations appear with decreasing frequency between 250 MHz and 50 MHz for a specific gas flow range. The frequencies are well within the range of the plasma ion frequency. Consequently, ion acoustic waves are discussed as a possible reason. Considering molecular argon ions as the dominant ion, densities are found to decrease from to . Evaluation of the plasma ion frequency creates a new possibility to determine ion densities.
PACS: 52.35.Fp – Electrostatic waves and oscillations (e.g., ion-acoustic waves) / 52.25.-b – Plasma properties / 52.70.-m – Plasma diagnostic techniques and instrumentation
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