Plasma (from Ancient Greek πλάσμα 'moldable substance') is one of the four fundamental states of matter, first systematically studied by Irving Langmuir in the 1920s. It consists of a gas of ions – atoms or molecules which have one or more orbital electrons stripped (or, rarely, an extra electron attached), and free electrons.
Plasma can be artificially generated by heating a neutral gas or subjecting it to a strong electromagnetic field. The presence of free charged particles makes plasma electrically conductive, with the dynamics of individual particles and macroscopic plasma motion governed by collective electromagnetic fields and very sensitive to externally applied fields. The response of plasma to electromagnetic fields is used in many modern technological devices, such as plasma televisions or plasma etching.Depending on temperature and density, a certain amount of neutral particles may also be present, in which case plasma is called partially ionized. Neon signs and lightning are examples of partially ionized plasmas.
Unlike the phase transitions between the other three states of matter, the transition to plasma is not well defined and is a matter of interpretation and context: Whether a given degree of ionization suffices to call the substance "plasma" depends on a specific phenomenon being considered. In other words, plasma is a matter which cannot be correctly described without the presence of charged particles taken into account.
Excluding dark matter and the even more elusive dark energy, plasma is the most abundant form of ordinary matter in the universe. Plasma is mostly associated with stars, including our Sun,
and extending to the rarefied intracluster medium and possibly the intergalactic regions.
Homework Statement
An idealized theta-pinch geometry is an infinitely long, cylindrically symmetric (d-by-d theta = 0), translationally-invariant (d-by-d z = 0) plasma column with an externally applied axial magnetic field B_z_ext. This induced a large diamagnetic azimuthal current which...
Hi. I'm thinking of doing a PhD in plasma physics, ideally to get into nuclear fusion research. But I am a little concerned that the opportunities with plasma physics are a little narrow. Does anyone know anything about its uses or otherwise in industry/non-fusion research? Thanks.
Hello All
I've got two years left in my Physics undergrad degree at a university in Ontario, Canada. My ultimate career goal is to do research in fusion energy, and I've just started looking into what steps I should take to get there, starting with grad school. Naturally, I have some...
Hi,
I do not know if this is the right section to post my question. Anyway here I go..
Can anyone give a brief explanation of Bohm's criterion, that is the concept of pre-sheath.
Thank you.
Hi, In collisionless plasma physics, when you integrate the Vlasov equation for the energy you find two equations : one for thermal energy of species s:
\frac{\partial u_s}{\partial t} + \nabla\cdot\left(\mathbf{q}_s + \mathbf{v}_s u_s + \vec{\vec{P}}\cdot\mathbf{v}_s \right) =...
Homework Statement
'Briefly describe two different kinds of plasmas and in each case describe how the plasma arises.'
Homework Equations
http://en.wikipedia.org/wiki/Plasma_(physics)
The Attempt at a Solution
I think i understand what a plasma is, but are there different types of plasma...
Hello,
In my plasma physics book, poissons equation in relation to a plasma made up of electrons and protons is given as
\frac{1}{r^{2}}\frac{d}{dr}\left(r^{2}\frac{d\varphi\left(r\right)}{dr}\right) = \frac{2}{\lambda_{D}}\varphi\left(r\right)
The solution of this equation when phi(r)...
Homework Statement
The dispersion relation for a plasma is given by
k^{2}=\frac{\omega^{2}}{c^{2}}(1-\frac{\omega^{2}_{p}}{\omega^{2}})\omega^{2}_{p}\:= \frac{Ne^{2}}{m_{e}\epsilon_{0}}
Where N is the electron density
During re enrty of a spacecraft there was a radio blackout of all...
Electromagnetic wave with higher frequency then plasma frequency are barely attenuated. I always hear that the reason is the electrons can't oscillate fast enought... how does that actually work? (how can an electron not be able to oscillate at the same speed?)
When i calculate a plasma frequency with the equation : ω=square root (4*pi*n*e^2/m)
are the electrons always of that frequency or is it a maximum that an electron can oscillate?
Why are electromagnetic waves reflected when they comme in contact with a plasma ( with a frequency lower then the plasma frequency, and I am trying to find precisely why the wave cannot pass ). I was also wondering if conductors (metals) are considered to have a plasma frequency
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My best offer for graduate school has turned out to be University of Wisconsin - Madison for the Department of Nuclear Engineering and Engineering Physics. I plan on focusing on theoretical/computational plasma physics and magnetic confinement fusion.
Does anybody have any personal...
What if any, is the best model that starts with the primeval plasma and produces any results
that would lead in some way to a universe?
Edit
I think i should have said simulation.
I just finished reading the Wikipedia article on the quark-gluon plasma and it states that because of the large coupling, lattice-gauge theory is used instead of perturbation theory/Feynman diagrams. However, I thought the coupling decreases with increasing energy (asymptotic freedom), so...
Hi everyone,
I'm not sure if this is a basic EE problem as I'm in aerospace and I would like to apologize if i posted in the wrong forum. I've attached a circuit diagram of my design. The capacitors and the 2 higher resistors are of variable values. The switch and the lower resistor...
how "large scale" is plasma physics
I'm a physics undergrad right now, and I'm trying to pick out classes I want to take to get a better idea of what I'd like to do in grad school. I've wanted to work on fusion/plasma physics for a long time, and right now I'm reading a book on the history of...
Hello all, I am currently a second year engineering physics major, specializing in Nuclear Engineering. What would be the best Math and Physics courses to get an idea of what fusion engineering and/or Plasma physics is like (My university does not offer any formal fusion engineering classes)? I...
50" 88lbs Plasma TV mount on Stand - Free Body Diagram
Hi,
I am building a customized stand for my palsma tv. I already have the base, made of 2" square iron tubes. I am about to design the mount for the screws, but I was wondering what forces should I consider for this.
The base is in...
I had a idea a while ago about a possible energy generator. I was wondering if you set up a plasma arc, then circulated gases through the arc so they would be ionized. Then, the ionized gases were moved through to a wire net through means of a strong fan or magnetic fields. Would it be...
Homework Statement
I'm trying to work out a theoretical problem, and I don't know how to approach it. Suppose I have a charged gas that is traveling near the surface of a magnetically-responsive solid.
I would expect the charged gas to be generating a magnetic field. I would also expect...
Gas core reactor rockets use nuclear gas reacting to super heat and therefore pressurize hydrogen. They operate at about 25000 C.
Why not use a high intensity plasma arc which routinely operate at about 13,000 C but if designed to can go much higher by at least several fold.
I got bored...
I believe it seems possible that a plasma generator could be constructed to ionize the gases used in the making of the plasma. A plan needs to be worked out to construct an energy collector to collect the energy that is given off by the ionization of the plasma gases. Now, in order to "recycle"...
Homework Statement
A cylindrically symmetric plasma column in a uniform B field (= B0 in z direction) has
n(r) = n0 exp[-(r/r0)^2] and ni = ne = n0exp[e phi/kb Te] where phi is the potential and Te is the temp of the electrons.
(a) Show that Ve and VDe are equal and opposite
Homework...
Is it possible to use plasma as a heat shield for a re-entry vehicle?
We all know that plasma isn't very dense, but then neither is the thin upper atmosphere that causes re-entry heating in lieu of drag.
I'd read that a simple trick used by ICBM warhead engineers, was to simply have a...
Homework Statement
Derive the moments equations for a plasma. I specifically need help developing the 2nd moment equation (the Energy Balance). I can't get one of the terms...
Homework Equations
The Boltzmann Equation:
\frac{\partial f_{\sigma}}{\partial t} + \vec{v}\cdot \nabla...
hey, I have a question, it might be really stupid, but I'm probably not as smart as any of you here. Anyway:
if you had a sustained plasma field held in place, maybe spinning in a toroidal motion, is it possible to "harvest" free electrons from the field by an anode, and feed it back into the...
In my physiology examination, I came across this question:
Find the Glomerular Filtration Rate (GFR), when
Urine Concentration of Urea (U) = 70 (I don't remember the exact values, but it is of no importance),
Urine flow rate (V) = 1ml/min
Blood level of Urea = 20 ( or something)
In...
There are many videos on youtube where people put grapes in the microwave and it turned the grapes into plasma. There are some other videos on youtube where someone made a plasma thruster(http://www.youtube.com/watch?v=s_wwEKp6SGk"), and in the discription said that it needed a magnetic field...
My parents have a 3yr old LG Plasma HDTV. Last month the color in the screen appeared to shift or fade. Then the screen started to flicker. Then the TV could be turned on with audio, but no screen, just black. The strange thing is that if we unplug the TV for a few hours and then plug it...
what happens to a body of water when coming in contact with plasma - such as the plasma cutters? I've been thinking if you had a cylinder filled with some water and something like a plasma "spark plug" you could get some serious vapor pressure.
Is this an accurate estimation, or am I way...
Hi:
Quark gluon plasma is created at very high temperature, right?. Could you please explain me what happens to Quark gluon plasma after it is cooled?, is it possible to use quark gluon plasma to create nucleons?
Thanks
I don't know if this belongs here but here it goes.
I started to think about it(not much however) when reading the last phrase in this thread
https://www.physicsforums.com/showthread.php?t=57607&highlight=plasma+physics
"As my QM professor kept saying this semester, "If you hate this...
Hello, I've been watching some videos on youtube of people putting a lit flame into a microwave oven. After a few seconds the flame bursts into a bright ball of plasma, why is this?
Is there anywhere online that I can research the science that causes this...
Does the concept of capacitance also apply to positively-charged plasma particles in a strong enough electric field? In other words, is it possible to accumulate positive gas ions on one side of some apparatus (or one side of a vacuum tube filled with a very small amount of gas) if a strong...
Hello all,
Are there any such major as for Plasma Physics or Plasma is just an option? What are the different types of Physics minus Astronomy? Is astrophysics part astronomy and part physics? If so we can forget about astrophysics. What are some good public not private colleges for physics...
Dear PFers,
could somebody provide an update on the searches for quark gluon plasma, the color glass condensate interpretation, and/or their conceptual basis ? I have found a few big documents, if somebody knows where to find the latest review it would be most welcome. I would like a preview...
When I have an ionized fluid (plasma) and I describe it in a continuum approach I can use the MHD equations (the continuity equation, the equation of motion, the induction equation and the energy equation).
However; I am modeling a certain model of a sunspot and there is also an unionized...
[SOLVED] light diffraction in plasma
This is my first post in that forum and I hope someone will help me.:redface:
It is known that photons with frequency lower than the natural oscillation frequency of plasma are reflected , but those photons with slightly lower frequencies are they fully...
A complete set of lecture notes for a graduate plasma physics course. Topics covered include particle orbit theory, fluid theory, wave theory, MHD theory, and kinetic theory.
by: Richard Fitzpatrick (University of Texas)
I am still trying to get a handle on plasma behavior, if I had a gap intended to apply a field for the purpose of compressing a hydrogen ion stream, using the Z-pinch effect could one discharge a current through the ion stream to affect the Z-pinch? I am thinking that it would, that the...
Hi,
I'm studying plasma waves now, and we have talked about waves in class that have phase velocities faster than the speed of light. For example, some of the waves from the Appleton-Hartree dispersion relation have this characteristic.
I asked my professor about it and he said that is...
I'm having a problem understanding QGP. Hadrons are bound states of quarks which interact by interchanging colour. Now, as I understood we haven't observed free quarks because the force rises by distance and that force is really strong. As I read in QGP quarks and gluons are not bound, you can't...