title: Electron drift velocities in He and water mixtures: measurements and an assessment of the water vapour cross-section sets.
abstract: The drift velocity of electrons in mixtures of gaseous water and helium is measured over the range of reduced electric fields 0.1-300 Td using a pulsed-Townsend technique. Admixtures of 1% and 2% water to helium are found to produce negative differential conductivity (NDC), despite NDC being absent from the pure gases. The measured drift velocities are used as a further discriminative assessment on the accuracy and completeness of a recently proposed set of electron-water vapour cross-sections [K. F. Ness, R. E. Robson, M. J. Brunger, and R. D. White, J. Chem. Phys. 136, 024318 (2012)]. A refinement of the momentum transfer cross-section for electron-water vapour scattering is presented, which ensures self-consistency with the measured drift velocities in mixtures with helium to within approximately 5% over the range of reduced fields considered.
authors.affiliation: Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, 62251, Cuernavaca, Mor., Mexico.
authors.forename: J
authors.initials: J
authors.lastname: de Urquijo
authors.affiliation: División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana, Av. San Pablo 180, 02200, México, D.F.
authors.forename: E
authors.initials: E
authors.lastname: Basurto
authors.affiliation: Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, 62251, Cuernavaca, Mor., Mexico.
authors.forename: A M
authors.initials: AM
authors.lastname: Juárez
authors.affiliation: School of Engineering and Physical Sciences, James Cook University, Townsville 4810, Australia.
authors.forename: K F
authors.initials: KF
authors.lastname: Ness
authors.affiliation: School of Engineering and Physical Sciences, James Cook University, Townsville 4810, Australia.
authors.forename: R E
authors.initials: RE
authors.lastname: Robson
authors.affiliation: School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia.
authors.forename: M J
authors.initials: MJ
authors.lastname: Brunger
authors.affiliation: School of Engineering and Physical Sciences, James Cook University, Townsville 4810, Australia.
authors.forename: R D
authors.initials: RD
authors.lastname: White
mesh_terms: D000390:Air Ionization; D004583:Electrons; D006371:Helium / Q000737:chemistry*; D012212:Rheology; D013227:Steam; D014867:Water / Q000737:chemistry*
chemical_list: D013227:Steam; D014867:Water; D006371:Helium