Electron-impact excitation ofn=2levels of helium at intermediate energies

Abstract

Five-state close-coupling equations for electron-helium scattering are solved in the energy region from 30 to 100 eV. Integral and diA'erential cross sections' for excitation of the ground state to the n = 2 states 2'S, 2'S"2'P, and 2'P are presented. Calculated shapes of differential cross sections versus angle for various energies are in fair agreement with measurements, but the magnitudes of the cross sections are overestimated. Allowance for coupling between 2'S and 2 P brings calculated differential cross sections into good quantitative agreement with experiment.

A new approach to computer experimental studies of atoms excited by electron impact - helium

“…of [12]. The results of the close-coupling (CC) method [8] are within a factor of 2 of the group of experimental results [12][13][14]. So we may consider that up to now the differential cross section for electron-impact excitation of the transition 1 1 S → 2 3 S in He at 40 eV is known with an accuracy of a factor of 1.5.…”

“…From the literature it is known that He is one of the most studied elements. But there is a strong discrepancy in results of different theory approximations [8][9][10][11]15] and in the natural experiment data [12][13][14] (we cite the works for 40 eV only).…”

“…We have a correlation for differential cross sections with natural experimental studies [12][13][14] and with theoretical results of CC [8] and CCC [15] methods within a factor of 2 for all studied scattering angles, except θ = 60 • . For θ = 60 • the correlation is within a factor of 2 of the experimental results of [14] and the CC method [8].…”

Electron impact excitation of helium in Debye plasma

“…Electron impact excitation processes of the free helium [1][2][3][4] atom have been widely investigated in previous years. Electrons scattering processes are very important for both gas discharges, laser systems, fusion plasmas, etc.…”

Unitarized first-order many-body approximation for the electron impact excitation of triplet states of helium

“…However, for energies above 30 eV the situation is not the same. Results from fivestate close coupling calculations of Bhadra et al (1979) are available, but most theoretical studies rely on some weak-coupling approach, like distorted wave (DW) (Mott and Massey 1965) and first-order many-body theory (FOMBT) (Csanak et a1 1971). Application of DW or FOMBT to helium (Madison andShelton 1973, Thomas et a1 1974) produces good results for the excitation of singlet states, however the agreement for the excitation of triplet states is worse.…”