Measurement of effective electron collision frequency in low pressure RF plasmas by the microwave resonator

Results of the experimental studying of effective electron collision frequency $\nu_{\mathrm{c}}$ with heavy particles in RF plasmas at pressure range from 13.3 up to 332.5 Pa is presented. The plasmas were created in a cylindrical quartz tubes from 20 up 40 mm by the diameter. The discharge power was varying from 100 up to 1000 W. RF frequency $f_{\mathrm{RF}}$ was varying from 1 up to 18 MHz. Diagnostics of the discharge was carried out by microwave resonators in UHF and microwave ranges. The probing signal frequency was varying from 5 to 12 GHz. The wave of $Å_{oso}$ type was excited in a cylindrical resonator. Average collision frequency and electron density $n_{e}$ in the discharge gap were measured. The collision frequency varies almost linearly in full range of $f_{\mathrm{RF\thinspace }}$varying. The collision frequency exceeds 10$^{\mathrm{10}}$ s$^{\mathrm{-1}}$ when p \textgreater 150 -- 180 Pa. Electron density $n_{e}$ is increased depending on voltage by linear low at low-power mode, and is increased approximately by square-law at high current mode.