Characterization of a low power 13.56 MHz RF atmospheric pressure plasma source for ion mobility spectroscopy

The development of an atmospheric pressure plasma source using a low power (< 100 W) 13.56 MHz RF power source is explored in this study. The inductively coupled plasma (ICP) source utilizes a 24 mm long, 7 mm diameter inductor and a custom-built capacitor connected in series to the RF power source. The ICP electrode enclose a glass tube where a 2 mm grounded tungsten rod is positioned at the center to realize and stabilize the breakdown of the gas inside the tube. A flow rate of 1-5 L min^-1 of Argon gas is utilized as the precursor gas. Observation of the ion species in the plasma and local plasma parameters are investigated using optical emission spectroscopy along the direction of the plume and perpendicularly using optical focusing methods. Double probe measurements of the plasma source are also investigated to observe the electrical characteristics of the plasma across the exit region of the plume. The results of the study are correlated to the ion transport from the plasma source to the exit region for ion mobility spectroscopy applications.