MEASUREMENT OF ELECTRON-IMPACT IONIZATION AND ATTACHMENT COEFFICIENTS IN NO2/HE GAS-MIXTURES AND ESTIMATED ELECTRON COLLISION CROSS-SECTIONS FOR NO2

The electron impact ionisation alpha/p(0) and attachment coefficients eta/p(0) in NO2/He gas mixtures, where p(0) is the gas pressure at 0 degrees C, are measured by a steady-state Townsend method over a wide range of compositions and E/p(0) values. Based on the experimental values of alpha/p(0) and eta/p(0), a preliminary set of the cross sections for NO2 is estimated by a Boltzmann equation analysis and values of the cross sections are discussed.