Measurements of electron drift velocities and positive ion mobilities for gases containing CF 4 II

Abstract

Measurements of electron drift velocities and positive ion mobilities for gases containing CF 4 have been made. Our previous paper described the results on electron drift velocities for gas mixtures containing CF 4 and hydrocarbon, and ion mobility results for gas mixtures of CF 4 + hydrocarbon, Ar + C 2H 6 and Ar + C 3H 8. The present paper is the second and final paper of the series. It describes the results on electron drift velocities for the gas mixtures; Ar + CF 4 + hydrocarbon, where hydrocarbon is CH 4 or C 2H 6 or C 3H 8 or iso-C 4H 10. The fraction of each gas component was changed systematically for each set of gas mixtures, and the electron drift velocity was measured as a function of the applied drift field between 0.2 and 2.5 kV/cm. Indications were found for relatively large electron drift velocities, even for low electric fields, with better saturation properties than was the case for the gas mixtures of CF 4 + hydrocarbon previously measured. Positive ion mobility was measured for several kinds of gas mixtures; Ar + hydrocarbon, CF 4 + hydrocarbon and Ar + CF 4 + hydrocarbon. Since ion currents and their arrival times were actually measured, the word “positive ion” does not necessarily mean a specific kind of ions but rather a group of ion clusters. The positive ion mobilities were deduced from this measurement under the assumption that Blanc's law was valid. A consistent picture was obtained within this approximation.