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Manuscript Title: The computation of the growth of a gaseous discharge in space-charge distorted fields.
Authors: A.J. Davies, C.J. Evans
Program title: SPARK71
Catalogue identifier: ABUD_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 3(1972)322
Programming language: Fortran.
Computer: ICL 1905E.
Operating system: GEORGE 2.
RAM: 19K words
Word size: 32
Peripherals: magnetic tape.
Keywords: Cathode, Electrical breakdown, Discharge, Plane-parallel Electrodes, Electron, Photon, Plasma physics, Space-charge, Positive ion.
Classification: 19.5.

Nature of problem:
SPARK71 computes the growth of ionization currents flowing between parallel plane electrodes. The effects which are incorporated are primary ionization, secondary cathode emission due to the incidence of photons and ions, space-charge distortion of the applied field, and the properties of the external electrical circuit.

Solution method:
The hyperbolic differential equations describing the growth of ionization in one dimension are integrated along the two characteristic directions in the x-t plane. Iteration in the t direction allows the change in the coefficients of the equations (due to field distortion) to be followed. The electric field is found from an approximation to the correct three-dimensional distribution. The x axis is divided into equal length meshes, and the time step is chosen to minimise the number of iterations needed.

As given in the listing, the program will accomodate up to 80 meshes in the x direction, and up to 4 photon secondary processes, each with its own characteristic delay time. (These numbers may be increased by changing the DIMENSION statements only.)