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Questions tagged [plasma-physics]

Theory, lab and space experiments, and calculations related the physics of plasmas, i.e., matter constituted by ionized atoms.

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Electron density Saha Ionization Equation

Saha-Boltzmann equation describes the ratio of number densities between any two consecutive ionization states and its product with the number electron density i.e. $$n_e\frac{n_{i+1}}{n_{i}}$$ Here, ...
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23 views

What are the applications of phase-integral method in plasma physics? [closed]

Which kinds of equations have to be solved by using phase integral method (Vlasov equation)? Are there any PHYSICAL phenomena explained by using this method? Or it is just a pure mathematical technics ...
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Creating Aurora-like phenomenon in a laboratory

Is it possible to recreate Aurora's in a laboratory experiment? Obviously, I'm not asking if it's possible to have bands of plasma thousands of kilometers long inside a lab. But rather, is it possible ...
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How many temperatures has a plasma?

In nonthermal plasma, not all particles move in the same way. The electrons are different from other particles. Both can be described as having a temperature separately. But that would mean, one piece ...
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Do plasmas really not experience a $\nabla \vec B$ drift even though the individual particles do?

I'm currently working through Chen's Introduction to Plasma Physics and Controlled Fusion, and I just got to the chapter on the fluid theory of plasmas. Chen claims that the $\nabla\vec B$ drift does ...
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40 views

Temperatures of Galaxy Clusters

Recently I've read about clusters of galaxies and have tried to understand how one can measure their mass and temperatures. Clearly, we can physically measure a couple of things such as the flux of X-...
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27 views

Modelling liquids like water with BBGKY-hierarchy

The BBGKY hierarchy is a well-known useful possibility to derive kinetic equations for gases and Plasma. The N-particle System is reduced to few-particle Systems by Integration over many Phase space ...
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1answer
44 views

Is looking at a toy plasma ball dangerous for your eyes?

I have a rather cheap USB toy plasma ball. Now I read, that plasma balls can be an eye hazard, if the glass does not filter the emitted UV light. I do not find many sources on how dangerous this ...
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33 views

Taking moments of the Vlasov equation

Given the following term: $\nabla_{v} \cdot \left[ \frac{e}{m_{s}} (\textbf{E} + \textbf{v} \times \textbf{B})f_{s} \right]$ where $\textbf{E}$ and $\textbf{B}$ are the electric and magnetic fields ...
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Plasma Frequency of Indium Tin Oxide

What does determine the plasma frequency? The formula is: $\omega_p² = \frac{4 \pi N e²}{m}$ and for frequencies above the plasma frequency the material is transparent. So for Indium Tin Oxide the ...
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1answer
29 views

Explain the equation describing total energy of the electrons in HET

I have this equation describing total energy of the electrons in HET (Hall-effect thruster): $$\frac{\partial (\frac{1}{2}mn(v_{ex}+v_{e\vartheta})^2 + \frac{3}{2}nT_e)}{\partial t}+\frac{\partial (\...
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Difference between solid and warm dense matter state

I found a theory paper, in which they discuss the absorption coefficient of a material as a function of the electron temperature. The electrons in the material are heated up by a free-electron laser. ...
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Would plasma that is as electron dense as lead be a better shield than lead against gamma radiation?

Imagine you somehow managed to maintain a body of plasma which had the same electron density as an identical volume of lead or other heavy metal. (Suppose you ionized lead.) Would it be a better gamma ...
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Opacity of ionized/non-ionized gases

In which state is matter more opaque to radiation? I'm talking about gaseous vs plasma. I know that opacity is a function of frequency in general, but I thought that, since a non-ionized gas has more ...
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1answer
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Plasma Waves at Different Frequencies

I am trying to determine what plasma waves appear at what frequency ranges. Particularly, I am interested in exploring plasma waves occurring between 100kHz to 1MHz. Is this a bad frequency range to ...
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1answer
32 views

How to measure an electron plasma with an electrically biased probe?

I want a crude way to confirm the existence of an electron cloud in a moderate vacuum of 2 mTorr. In my set up, filaments emit electrons into a magnetic trap which concentrates them (similar to an ...
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29 views

What is a flux conserver and how does it work?

A number of plasma physics papers I've seen mention "flux conservers", e.g. this paper. However, despite my best efforts, I can't find a good description of a flux conserver or how it actually works. ...
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Unmagnetized plasmas in space

Please, I need some information about high temperature plasmas in astrophysical environments. To my knowledge, plasmas in astrophysical environments are magnetized (is it true?). Are there ...
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Debye screening in $\mathbb{R^d}$

Consider the Poisson-Boltzmann equation $$ \nabla^2 V(r) = -\frac{1}{\epsilon_0}en\left(1 - e^{e V(r)/k_BT}\right) $$ which models the electrostatic potential in a spherically symmetric ideal gas of ...
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A question about the properties of plasma and its potential use in recycling

I have multiple questions linking into a potential recycling method; I'm curious if any of these ideas are possible, or if I'm having a pipe dream: Can any gas be turned into plasma? Can multiple ...
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36 views

Solution of the diffusion equation in a plasma

considering the diffusion equation taking into account diffusion and mobility of charged particules in a plasma of density $n(z)$ and potential $\phi(z)$, we have : $$ \frac{n(z)}{\tau}=\frac{\...
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Timescales of plasma recombination and fluorescence?

I am currently working on a very simple model for the radiation from electric arcs. As both fluorescence (internal electronic transition) and plasma recombination occur, I would like to compare the ...
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36 views

Question about normalizing fluid quantities (plasma physics)

I'm having trouble understanding the way the plasma fluid equations are normalized in Ch. 4 of Fitzpatrick's "Plasma Physics: An Introduction." Here's a a link to the page in question. Equations 4.147-...
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Regarding the $E x B$ drift in the Earth's magnetic field

So I have a burning question: The only reason that the E x B drift doesn't generate an electric current is because both the electrons and the positive ions move towards the same direction (towards ...
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2answers
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Math needed for plasma physics? [closed]

I am curious about what kind of math is needed for studying plasma physics, especially for the magnetohrodynamics. I know there are lots of PDEs in plasma physics, but how about real analysis? Or ...
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1answer
22 views

Is there a limit on the magnetic field in a Hall generator?

In a Hall generator, charge accumulation on electrodes occurs because there is a generated current, $\bf{J}$, in a magnetic field, $\bf{B}$. This results in charge separation due to a Hall current ...
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1answer
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What is the solar wind speed as function of distance from the Sun?

Someone must have calculated at least a "zero-order approximation" of the behavior of solar wind speed, density, and pressure as a function of distance from the Sun, but the heck if I can find it. ...
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What determines the color of the light emitted in a Tokamak?

We see images of Tokamak plasma with all sorts of colours from red to purple. Why do we see any light at all, since the plasma should be so hot to have dissociated all its electrons? It is all from ...
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Do radio beams self-focus in the interstellar medium?

Summary: In a plasma, electromagnetic waves create a ponderomotive force that pushes electrons and ions out of the way. Thus, in an intense laser beam, electrons tends to move away from the areas ...
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1answer
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Linearization of MHD equations for a cold plasma and low frequencies

I'm trying to convert the next equations for a cold plasma (consider $P=0$ the pressure), for low frequencies and ignoring dissipative effects: $$\rho \left(\left(\frac{\partial \vec{v} }{\partial t}\...
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1answer
31 views

Physical significance of growth rate in plasma

Let us say that we have a dispersion relation curve and associated instability curve as shown below for a magnetised plasma, which have been formulated through kinetic theory. The frequencies and ...
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2answers
79 views

Extreme high voltage path of least resistance changes?

In this video, there is an extremely high voltage being sent through a blank breadboard. The arcs go through different, seemingly random new paths. What causes this? How could you determine what the ...
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1answer
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How can there be an electric field normal to the surface in a surface plasmon in a metal

Ashcroft and Mermin's Solid State Physics, chapter one, has an exercise about surface plasmons. They give the electric field normal to the surface of the metal as $E_z=Be^{iqx}e^{-Kz}$ How can this be?...
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Plasma and helicon wave frequencies in iron according to Drude model

The first chapter of Ashcroft and Mermin's Solid State Physics discusses electromagnetic waves in metals. One of the exercises requires calculation of the plasma and helicon frequenies using the Drude ...
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How does the energy of a solar flare propagate?

Does it radiate outward, spherically, or is it more directed? Is there some opening angle? Is it more complex than this?
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Is exercise 4, part b of chapter one of Ashcroft and Mermin wrong?

This is from Solid State Physics. It is about helicon waves in a metal. When I take the curl of the given electric field it does not equal zero even though the magnetic field is static. Is this an ...
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What is the electrical resistivity of air during breakdown?

There is a well-documented theory for breakdown voltage vs pressure in the form of Paschen's law. But what is the trend of the electrical resistivity of air as a function of the electric field ...
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Energy Equation of an ideal gas in expanding space-time

Short question: If the energy equation of an ideal plasma is written as follows: $\begin{equation} \frac{\mathrm{d}p}{\mathrm{d}t}=-\Gamma p\nabla\cdot v-\left(\Gamma-1\right)\left( \nabla\cdot q-\...
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Can some one tell me what can detect the accurate gas electric conductivity? [duplicate]

Can someone tell me how and what kind of gas could conduct electricity and what instrument could detect it?
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76 views

Significance of the ion Hall parameter

For an ionized Helium gas, for example, MHD Hall generators rely on the mobility ratios between electrons and ions to function and produce a Hall current. As far as I can tell, intuitively, increasing ...
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How to derive Walen's equation? [closed]

This is perhaps a simple math problem, therefore no books ever given detail calculation. Could someone help to give a proof? We have continuity eqution as $\frac{\partial\rho}{\partial t} = -\rho\...
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3answers
128 views

Is it possible to have a liquid plasma?

Plasmas are generally thought of an ionized gases, which are conductive and can respond to electric and magnetic fields. However, I was just wondering if it is possible (in theory or in practice) to ...
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Examples of perturbative force-free electrodynamics on top of vacuum solutions?

Imagine I have a solution $A_{(0)\mu }$ for the four-vector potential of vacuum electrodynamics. That is, the solution fulfills source-free Maxwell equations $F^{\mu\nu}_{(0)\;\;;\nu} = 0$ with $F_{(0)...
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How is fusion reactor fuel initially accelerated?

If, in a nuclear fusion tokamak reactor, you start with neutral fuels, how do you accelerate the atoms fast enough to start the reactor? Or do all of the particles have to ionized to begin with?
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If a mix of elements in a plasma are frozen rapidly, does the crystalline structure of the frozen material reflect the plasma phase?

If you have a mix of elements in a plasma, with ions flying around freely, and you freeze it, would you see reflections of that plasma phase in the crystalline structure of the frozen material? Plasma ...
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1answer
31 views

Ideal MHD stability with a Fourier analyzed perturbation

I'm learning through the basics of ideal MHD instabilities and the textbook (Friedberg, Plasma Physics and Fusion Energy, 12.4-12.6) writes the linearized momentum equation in terms of the ...
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When can we say $x$ and $p$ are “independent variable”, in order to find the Vlasov equation?

I have a question about "independent variable" in physics, and especially variable in Lagrangian or Density Function. I read several questions about it in this forum and although I have the feeling I ...
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1answer
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Electron distribution in Low Earth Orbit

I have been searching online for some kind of pdf function that describes the charged electron distribution in Low Earth Orbit in regards to their energies. Any ideas on whether something like that ...
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1answer
52 views

Application of Darboux's theorem to magnetic field line flows

In this famous paper by Cary and Littlejohn on noncanonical Hamiltonian mechanics and its application to magnetic field line flow, they claim that as a result of Darboux's theorem, it is always ...
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What is a quasi-axisymmetric stellarator?

I know that a tokamak is a donut shape fusion confinement device with an axisymmetric magnetic field configuration. The stellarator is similar but its field configuration is non-axisymmetric. I've ...