R.P. Singhal

Auroral and photoelectron fluxes in cometary ionospheres

Photoelectron and auroral electron fluxes in cometary ionospheres have been studied in detail using the analytical yield spectrum approach. The effects on photoelectron fluxes of cometocentric distance, solar zenith angle (using generalized Chapman function), and solar minimum and maximum conditions, on the assumption of local energy deposition, are determined. Energy loss to ambient electrons is accounted for. Auroral electron fluxes are calculated for monoenergetic and observed primary electron spectra. The results are compared with other theoretical works and good agreement is found. Auroral electrons make a larger contribution to the observed electron spectrum compared with the extreme ultraviolet-generated photoelectrons.

Impact-parameter dependence of ionization probabilities of the L sub-shells

Abstract Ionization probabilities of the L I and L III subshells have been calculated for 82 Pb by the impact of protons with in the frame work of binary encounter approximation (BEA) theory. The results obtained have been compared with the probabilities based on semi-classical approximation (SCA) theory.

Binding-energy correction for atomic L-shell ionization by heavy charged particles

Abstract During the process of inner shell ionization of atoms bu low-velocity heavy charged particles the effective binding energy of the target electron is changed due to the presence of the incoming projectile. In the present work we have calculated the binding energy corrections for the ionization of 2s and 2p sub-shells of the target atom employing approximate expression for L-shell ionization based on a semi-classical approximation (SCA). The binding energy correction thus obtained has been incorporated in the classical binary encounter theory of ionization to calculate the L-shell ionization cross section of argon by the impact of low energy (50–200 KeV) protons. The results are compared with the available experimental data.

Electron loss cross sections for He+ and He incident on N2 and O

Abstract Electron loss cross sections for He + and He incident on molecular nitrogen and atomic oxygen are calculated using the free collision model. Accurate analytical expressions for differential elastic cross sections needed in the free collision model have been used. Good agreement with available experimental data is found at high impact energies when the free collision model is applicable.