Fundamental properties of radiofrequency and microwave surface-wave induced plasmas

Abstract

Some fundamental properties of radiofrequency and microwave surface-wave induced plasmas were determined in the frequency domain from 200 to 2450 MHz. Argon and helium plasmas at atmospheric pressure were sustained under various experimental conditions (absorbed power, flow-rate and enclosed or open-air discharges). Excitation temperatures were found to be approximately 2400 K for argon and 3000 K for helium, whereas rotational temperatures (N₂ and N₂⁺) were lower (2000 K). Electron densities were in the range 3–4 × 10¹⁴ e cm^–3 for argon and were a factor of three lower for the helium plasma. Under these operating conditions, frequency proved to have little or no effect on the fundamental parameters measured.