Friday, February 19, 2010

Non-Neutral Plasma Physics II

I didn't realize until today how long it had been since my last post...when you're busy, you're very busy, I suppose. For this post, I'll give a little more background on the non-neutral part of the plasmas.

Last post I mentioned my current research group at BYU, the plasma physics group, and explained a little about plasmas in general. Most plasmas I mentioned in the last posts are neutral plasmas - in other words, there is enough energy in the system to remove electrons from their atoms, then keep them removed (given the chance, a system, like a nucleus with electrons orbiting around it, will want to fall into the lowest possible energy state, and electrons bound to a nucleus in atom form have much lower energy than free floating electrons and nuclei). Temperatures required to keep a neutral plasma in its plasma form are  high - the average temperature for the plasma in the sun, for example, hovers around 10,000 degrees kelvin - hence there is little to no naturally occurring neutral plasma sources on the earth itself (at least that I know of).

To get around this problem, physicists will actually separate the free flowing electrons from their nuclei, creating groups of electrons and groups of ionized nuclei (nuclei with some or all of the orbiting electrons removed). With those electrons removed, the nuclei (and the electrons, as it turns out) will still have many of the properties of the neutral plasmas without the need to keep those plasmas at high temperatures, and thus the non-neutral plasmas can stay in their plasma state for far longer than the original, neutral plasmas.  In fact, the research group at BYU intends to keep those plasmas in their plasma state for weeks, even months if possible.

Now, one may wonder where the name "Non-neutral" came from, anyway. Well, with neutral plasmas, even though the nuclei and the electrons are no longer physically bound, the number of positively charged protons in the system will still equal the number of negatively charged electrons, a state which physicists consider "electrically neutral". After the electrons have been removed from the system, however, the remaining ionized nuclei will have a net positive charge and will no longer be neutral, hence the name "non-neutral plasmas".

That's all for today. I'll post more later on the specific research that we are doing at BYU (assuming that I'm allowed to, of course. :P)

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