  Electron neutral collision frequency is measured using both grounded and
floating hairpin resonator probes in a 27 MHz parallel plate capacitively
coupled plasma (CCP). Operating conditions are 0.1-2 Torr (13.3-267 Pa) in Ar,
He, and Ar-He gas mixtures. The method treats the hairpin probe as a two wire
transmission line immersed in a dielectric medium. A minimization method is
applied during the pressure and sheath correction process by sweeping over
assumed collision frequencies in order to obtain the measured collision
frequency. Results are compared to hybrid plasma equipment module (HPEM)
simulations and show good agreement.
