IOP Publishing, Plasma Sources Science and Technology, 3(14), p. 467-476, 2005
DOI: 10.1088/0963-0252/14/3/008
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The design of a miniature low-power atmospheric pressure glow discharge torch (APGD-t) and the results of its preliminary electrical and spectroscopic characterization are presented. A capacitively-coupled pulsed RF (13.56 MHz) helium plasma jet is formed in a converging confinement tube and O2 is injected downstream in the plasma afterglow region through a capillary electrode. With 1 SLM He, the APGD-t produced a non-thermal plasma jet of 500 µm-diameter and ≈2.5 mm-long at power levels ranging from 1 to 5 W. At ≈1 W, the gas temperature and He excitation temperature near the nozzle exit were ≈50°C and slightly below 2000 K, respectively. The breakdown voltage in 1 SLM He is approximately 220 Vpk−to−0. Careful electric probe measurements and circuit analysis revealed the strong effect of the voltage probe on the total load impedance. The injection of 10 SCCM O2 through the capillary electrode led to the transport of atomic O further downstream in the plasma jet and to a slight increase of the He excitation temperature without significant effects on the electrical properties and jet length. Alternatively, the addition of an equivalent amount of O2 (1 v/v%) to the plasma-forming gas affected the electrical properties slightly, but led to a drastic contraction of the plasma jet. The atomic oxygen production and transport conditions provided by the APGD-t are promising for precise bio-applications such as the treatment of skin tissues and cells.