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Manuscript Title: Electron energy deposition in a gaseous mixture.
Authors: L.R. Peterson, T. Sawada, J.N. Bass, A.E.S. Green
Program title: ELECTRON ENERGY LOSS
Catalogue identifier: ACRH_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 5(1973)239
Programming language: Fortran.
Computer: IBM 360/65.
Operating system: SYSTEM 360.
RAM: 40K words
Word size: 32
Keywords: Electron impact, Liquid state physics, Excitation, Ionization, Energy degradation, Loss function, Continuous slowdown Approximation, Aurora, Airglow, Nuclear physics, Energy loss.
Classification: 12, 17.2.

Nature of problem:
This program apportions the energy deposited in various atomic and molecular excitations and ionizations when an electron impinges upon a prescribed mixture of gases. The basic electron impact cross sections for each species are inserted using parameterized forms which have been found to adequately represent such data. Relative populations and excitation efficiencies for all atomic or molecular states are computed following the complete energy degradation of the primary electron and all generations of secondaries formed during ionization events.

Solution method:
The method of solution has evolved in a series of works. In this formulation, the continuous slowdown approximation is assumed along with the condition of local absorption of the electron beam. The loss function L(E) = 1(1/n)dE/dx plays the central role. It can be constructed internally from the complete sets of input cross sections or it can be estimated externally and read into the program along with the relevant subset of cross sections. The energy bookkeeping calculations then reduce to numerical or analytical integration of functions involving cross sections and the loss function.

Restrictions:
Standardized parameterized forms must be used for inserting cross sections. These are available for a number of important atmospheric gases. However, many options are available which make the program very flexible.

Running time:
The running time is variable depending upon detailed input. Runs involving one gas with a total of 5 ionization continua and ~~20 excitation states require about 15 s when the electron is degraded from 1 KeV.