In article ,
Martin Brown writes:
Fully ionised plasmas are to a very good approximation black body
emitters.

This may not have come out exactly as the writer intended. Fully
ionized plasmas emit as blackbodies only if they are optically thick
and isothermal. Galactic H II regions and planetary nebulae are
perhaps the most familiar fully-ionized plasmas (at least to
astronomers), and their emission looks nothing like a blackbody.
That's because they are optically thin (and not entirely isothermal
either). Nevertheless, there is nothing special about plasmas that
prevents them from emitting as blackbodies in the right conditions.

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
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