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Manuscript Title: The potential created by an alternating point charge in a Maxwellian magneto-plasma.
Authors: J. Thiel, P. Dorio, C. Soubry
Program title: POTENT
Catalogue identifier: AAQP_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 23(1981)169
Programming language: Fortran.
Computer: CDC7600, SIMPLE PRECISION.
Operating system: SCOPE 2 - LEVEL 280.
RAM: 164K words
Word size: 60
Peripherals: magnetic tape.
Keywords: Plasma physics, Forced potential, Point antenna, Wave plasma, Electrostatic waves.
Classification: 19.13.

Nature of problem:
Computation of the potential created by an alternating point charge in a stationary Maxwellian magneto-plasma, neglecting ion motion and collisions, for a broad range of values of the distance vector from the source and of the plasma frequency, when the excitation frequency is below the cyclotron frequency.

Solution method:
By using the least-damped-root approximation, the potential is expressed as a single integral over the field-aligned component k|| of the wave vector. The calculation of this integral only needs the knowlegde of least-damped root of the dispersion equation for electrostatic waves, together with its derivative, as functions of k||. They are obtained from a complete set of tabulated values on a magnetic tape by using a second-order Newton interpolation method. As a first step, the values of the least-damped root and of the derivative are read from the magnetic tape, and a double interpolation is made with respect to the excitation and the plasma frequencies. Then the numerical integration is performed over successive five-point intervals by an iterative method, in which integration by Filon's method and interpolation over k|| by Newton's method are made together, until the required accuracy is reached. The total integral is then computed as the sum of the convergent series obtained by adding the partial integration results.

Restrictions:
The only restrictions of the problem are:
1) The distance from the source must be greater than 5 and less than 1000 times the Larmor radius.
2) The plasma frequency must be greater than 0.1 and less than 41 times the cyclotron frequency.
3) The angle between the distance vector and the magnetic field direction must be different from 0.

Running time:
The test run output, comprising 52 values of the potential, is computed in about 276.173 s.