Newsgroups: sci.physics.plasma
From news@bignews.shef.ac.uk Wed Jan 24 10:33:16 1996
From: G.R.Harris@sheffield.ac.uk (G Harris)
Organization: University of Sheffield, UK
Subject: Re: atomic process cross section data

Bruce Scott TOK (bds@ipp-garching.mpg.de) wrote:
: Mirko Vukovic (mirko.vukovic@grc.varian.com) wrote:
: : What are good sources of cross section data for atomic processes (ionisation,
: : excitation, Penning, charge exchange)?

: Look for a book by Janev et al, Elementary Processes in Hydrogen-Helium
: Plasmas (Springer, 1987). It has graphs, tables, and polynomial
: approximations for most of the stuff you are looking for. I think there
: is a companion volume for "impurities" out by now.

Note however that the polynomial fits for the rates <sigma v> are
made over a range of temperatures whose minimum value is often as
high as 2eV (a typical temp. for the low power discharges I'm
currently looking at). The <sigma v> fits seem sensible for
temperatures lower than this, but on integrating sigma over a
Maxwellian myself to check this, I seem to recall getting small
but significant differences over the whole temperature range.
This is possibly due to me averaging not the original data
for sigma (unavailable), but the polynomial fit to it.
[Of course, at these low temperatures, the electron dist.
function is not likely to be Maxwellian anyway].

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Glen Harris, Chemistry, Sheffield Univ, GB, tel 44-114-2824518
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