Townsend Discharge in Methane at Very High E/N

We show preliminary comparisons between experimental data and Monte Carlo simulations for the spatial profiles of excitation coefficients for the molecular band CH $(A2-X2)$ produced in dissociative excitation by electron swarms and fast neutrals in methane. Measurements were made in parallel plate drift tube for E/N values between 500 Td and 11000 Td (E- electric field, N- gas density, 1 Td = 10-21 Vm2). The spatial profiles of emission reveal significant heavy particle excitation even at moderately high E/N. Calculated absolute profiles are in excellent agreement with the experimental results. The calculations were based on the heavy particle cross sections of Petrovi\'c and Phelps [1]. \newline [1] Z.Lj.Petrovi\'c A.V.Phelps (1992) unpublished.