LABORATORY ON PLASMA AND CONVERSION OF ENERGY-UMR5213

Download version 1.1:

Overview

BOLSIG+ is a user-friendly Windows application for the numerical solution of the Boltzmann equation for electrons in weakly ionized gases in uniform electric fields, conditions which typically appear in the bulk of collisional low-temperature plasmas. Under these conditions the electron distribution is determined by the balance between electric acceleration and momentum loss and energy loss in collisions with neutral gas particles.

The main purpose of BOLSIG+ is to obtain the electron transport coefficients and collision rate coefficients from collision cross section data.

The principles of BOLSIG+ can be summarized as follows:

• the electric field and all collision probabilities are assumed to be uniform
• the angular dependence of the electron distribution is approximated by the classical two-term expansion
• the change in the electron number density due to ionization or attachment is accounted for by an exponential growth model
• using the above assumptions, the Boltzmann equation reduces to a convection-diffusion continuity-equation with a non-local source term in energy space, which is discretized by an exponential scheme and solved for the electron energy distribution function by a standard matrix inversion technique.

Usage

The main input data for BOLSIG+ are tables of the cross sections for the different types of electron collisions versus the electron energy. A standard input file is included with the electron cross sections for common gases*, but the user can edit his own input files. Other input parameters such as electric field strength, gas composition, etc, are handled via the user interface.

Output data are the electron energy distribution function and the electron-related transport coefficients and rate coefficients. The BOLSIG+ interface includes options to quickly perform series of calculations and generate tables of transport coefficients and rate coefficients as a function of the reduced electric field or the mean electron energy, which can be used as input data for fluid models of gas discharges. Calculation results can be quickly viewed in tables or graphs on the screen, and can be stored on disk in various text file formats.

*The cross section file distributed with BOLSIG+ is the same file previously distributed with BOLSIG. Although it has been compiled with care, we cannot guarantee accuracy or completeness.

Background

BOLSIG+ is an improved and extended version of the BOLSIG solver commonly used in the low-temperature plasma research community. With respect to BOLSIG it is more general, easier to use, based on more efficient numerical techniques, and paying more attention to a consistent definition of the transport coefficients and rate coefficients for fluid models.

Additional physics included in BOLSIG+ with respect to BOLSIG:

• electron-electron collisions
• different models for changing electron number density temporal growth or spatial growth
• high-frequency oscillating electric fields
• more consistent definition of transport coefficients.

Author

BOLSIG+ has been developed by Gerjan Hagelaar of the Laboratoire Plasma et Conversion d’Energie (LAPLACE), Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 9, France

Download

BOLSIG+ is available for public download. A short users’ guide is included. The current is version 1.1- 07/2008. Recent corrections and improvements include:

• correction of the diffusion coefficient from the temporal growth model at high reduced field; in version 1.04 and earlier, growth effects were forgotten in the diffusion coefficient
• energy-conservation check to obtain better convergence in case of many electron-electron collisions (high ionisation degree)
• correction of errors in He and H2 cross sections in data file, small errors in the Ar momentum transfer, and the mass ratio, m/M for Hg. Current file is sigsept08.sec (in "new format").

Copyright

Permission to use BOLSIG+ is hereby granted, provided that proper reference is made in any publications making use of the data generated by this software. BOLSIG+ has been developed for clearly defined purposes and is made available "as is". No assistance or support is provided. The author makes no warranty about the suitability of the software for any purpose. Downloading BOLSIG+ from this site is implicit acceptance of these conditions. Users should check this site periodically to see if upgrades are available or if errors have been reported.

Publication

G.J.M. Hagelaar and L.C. Pitchford, "Solving the Boltzmann equation to obtain electron transport coefficients and rate coefficients for fluid models", Plasma Sources Sci. Technol. 14 722-733 (2005).