The ratio of radial diffusion coefficient to mobility for electrons in hydrogen, nitrogen and carbon monoxide at high E/N

Measurements of the ratio of radial diffusion coefficient to mobility, D r / mu , have been obtained for carbon monoxide, nitrogen and hydrogen. A pulse technique has been used covering a wide range of E/N from 28 to 5650 Td. The values of D r / mu vary between 0.8 and 17 eV in carbon monoxide, between 1.2 and 16 eV in nitrogen and between 1 and 12 eV in hydrogen. Comparison has been made with results of a Monte Carlo computer simulation. For all the gases, fair agreement has been obtained with the theory except for the highest of range E/N. This discrepancy has been explained by the presence of a non-equilibrium electron energy distribution in the experimental measurements.