From: adder_black_the@yahoo.com (Steve Ivy)
Newsgroups: sci.physics.plasma
Subject: Re: Photon frequency loss on collision
Date: 13 Jan 2002 21:48:04 -0800
Organization: http://groups.google.com/
References: <a1sloi$bvph$1@saturn.cs.uml.edu>


Hanson asks the question "what happens when a photon collides
with an H-atom".

I also would like to hear what the experts have to say to that
more general query but more to the point I want to know what
happens when a photon (or more specifically a powerful laser
beam) strikes a well ionized D T plasma?

I know that sufficiently energetic photons interact with matter
by raising one or more electrons of the affected atom to a higher
energy band. After some short time a new less energetic photon
will be emitted by the no longer excited atom as the the formerly
excited electron falls back to it's ground state either directly
of by passing through several intermediate steps possibly
emitting multiple lower energy photons long the way.

I believe that any additional energy left over from this
transaction (hv)1 - (hv)2 will be expressed as increased
residual thermal energy of that atom.

There are of course several other interesting cases.

One where photon energy is lower than the minimum required to place
any electrons up to the next higher energy state.

One where the photon is sufficiently energetic to actually
totally ionise the atom.

And thirdly one where the photon is so energtic as to actually damage
the nucleus of the atom.


The main points I have questions about are

1) What effect do (high, low and, mid) energy photons have on a plasmas?

I mean if there are no longer any bound electrons in a fully ionized gas
what effect would an additional high flux of photons of various
energys relative to the natural ionization energy for that material
have on the materail? With particular thought to the case where the
material is D and or T?


What about the same case as above where the power or photon flux is very
high.

2) Do the electrons of such a plasma interact with the photons?


3) If an ion can continue to absorb additional energy via this
mechanism how is that energy absorption presented? As increased
thermal energy?

Please address any stupid assumptions I have made here gently. I am not
willfully ignorant nor would I intentionally lead anyone else astray.

Thanks: Steve Ivy


"hanson" <hanson@quick.net> wrote in message news:<a1sloi$bvph$1@saturn.cs.uml.edu>...
> Photon frequency loss on collision
>
> Does a photon loose energy when colliding with a H-atom, in a very dilute
> gas, like in intergalactic space?
> How much, what fraction, of its incident frequency does a photon lose when
> encountering and colliding with an H atom?
> It is said that there are all kinds of interactions possible from
> ionization to transnational, well, translational, and rotational states.
> But I don't want to have a rehash of Bohr, Heisenberg and Moessbauer
> theories.
>
> What I like to know is whether there is (perhaps) a common loss ratio of
> energy between incidence and emission of delta f / f, no matter what the
> initial hf of the photon is?
>
> In case one insists hat hf-in = hf out, that NO frequency loss occurs
> between absorption and emission, then the question arises: What does the
> work, what makes this (unit=1) process happen?
>
> hanson