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)

Non-Neutral Plasma Physics I

I thought it might be fun to describe the research group I'm in, the Non-Neutral Plasma Physics group at BYU.

First, I'll need to explain a little about plasma in general: Plasmas are the fourth state of matter. Most people are aware of solids, liquids, and gases - each of these states of matter have various structures and densities based on the energy the molecules of the substance have and the innate chemical properties of the matter. Changing from one state of matter to another requires inputing or extracting energy from the system the energy is in; we commonly refer to these changing points as the Melting Point (changing from a solid to a liquid and vice versa) and the Boiling Point (changing from a liquid to a gas) of the substances in question.

In all of these states of matter, we generally have (using a classical model) electrons bound to the atoms in the molecule more or less permanently. In plasmas, however, (I'm talking about neutral plasmas right now - non neutral plasmas are slightly different), the temperature (and hence the kinetic energy) of the matter is high enough to separate the electrons from the atoms they are originally connected to permanently. The result is a gas-like substance with free floating nuclei and electrons.

Since most of matter we encounter in our daily lives is one of the three traditional states of matter (solids, liquids, and gases), it may come as a surprise (it did for me) that the majority of the matter in the universe that we know of resides in the plasma state. The sun, for example, is hot enough to keep the matter inside of it more or less constantly in the plasma state, and the space in-between consists of large amounts of plasma as well. Unfortunately (or fortunately for scientists like me :) ) since plasma is relatively rare on the surface of the earth, knowledge of the state of matter lags behind that of gases, liquids and solids, and plasmas constitute a heavy area of research in physics.

This post has already gotten rather long, so I'll leave it at this. Next Time: Non - Neutral Plasmas!