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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Magnehydrotostatic equilibrium

in plasma physics the magnetostatic equilibrium is defined as $$ \vec{j}\times\vec{B}=\nabla p $$ where $\vec{j}$ is the current density $\vec{B}$ is the magnetic field and $p$ is the pressure. But ...
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Why the Tokamak Fusion Reactors need to be so big if electromagnetism works better for small distances?

I'm probably asking something dumb, but for the little I think I know, I assume that the bigger the electromagnetism field, the bigger the energetic requirement. I'm assuming that the square cube law ...
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Question to multi-component fluids

I have read these lecture notes: http://geo.mff.cuni.cz/~soucek/vyuka/materials/theory-of-mixtures/theory_of_mixtures-lecture-notes.pdf Now look at page 41: There are 4 different types of mixture ...
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How is the solar magnetic field produced?

I have been trying to understand the magnetic field creation mechanism. I know that its origin is not perfectly understood, but what is currently believed (as I know) is that the magnetic fields ...
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Are all turbulent flows chaotic?

I have often read that all turbulent flows are chaotic. I have come across a few explanations on web forums, but are there any authoritative references/textbooks that explicitly cover this question?
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Radial dependence of temperature for adiabatic expansion of ideal gas

If the solar wind propagates out adiabatically with a constant speed and can be regarded as an ideal gas, how the solar wind temperature depend on radial distance from the sun $r$, i.e. $T$ as a ...
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Plasma Physics emissivity

When doing research in plasma physics. The emissivity of plasma is usually less than 1. Why is it important to measure the plasma emissivity?
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What will happen when an object temperature rise but don't stop? [closed]

Like a substance heat in state of solids at a certain point covert into liquid, gas and plasma and my question is what will happen when we heat plasma continuously with rising temperature
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Is it generally accepted that Field Aligned Currents are caused by Force-Free Fields?

I am currently an undergraduate working on a project about FAC (Birkeland Currents) and it seems that most of the sources on the subject are very technical and hard for me to read (particularily ...
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In view of the frozen flux theorem, why don't stars have much stronger magnetic fields?

According to the frozen flux theorem or Alfvén's theorem, the magnetic field in a plasma is frozen into the plasma and must move along with it. That is, in an ideal plasma, the magnetic flux through ...
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Change in photon production rates due to finite temperature / a QED plasma?

I have the following question: In a QED plasma, the photon technically gains a "mass" due to a change in its dispersion relations. I was wondering, if the photon also acts as massive during ...
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In a light plasma, how many electrons pass through a given area

Assume you have a light plasma of about 10^5 particles per cm^3. The energy-density of the plasma is about 0.1eV (as in near earth orbits, see here: http://assets.press.princeton.edu/chapters/s9500....
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Can I track hypersonic missiles with heat sensors? [closed]

On a video, it is said that hypersonic missiles create an plasma layer that scatters radar waves, therefore hard to detect And then, on another video, it demonstrates anti-ballistic missile system ...
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Chemical Potential of an electron or positron in a pair production reaction

In the Thorne and Blandford Modern Classical Physics text there is an exercise that walks you through deriving the density-temperature limit for pair production in plasmas. To do this they consider a ...
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How does two-wavelength interferometry mitigate vibrations in density measurements?

I am currently using interferometry to measure the density of a plasma. The interferograms are suffering from vibrations, and I know that two-wavelength interferometry may mitigate this. I am however ...
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Recombination time in air

Conditions Im interested in: air, 1 atm, 300K, very low ionization percentage, electrostatic source of ionization, reduction in ionization percentage two fold. But general answer is ok too. Data I ...
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Why radial radiation profiles of axisymmetric electric arc cross section is Gaussian?

I've recently found from experiment data that, the radial intensity profiles of an axisymmetric electric arc cross section is pretty close to Gaussian Distribution (R-square>0.99). fitting image ...
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Energy ionization of degenerated matter

Distance between electron and atomic nucleus in degeneracy matter is lower than non-degenerated matter. Electron energy binding with the nucleus must be higher. Whether temperature needed to ...
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What is the field emission current at very high voltages?

Consider two planar metal electrodes at low temperature, separated by vacuum, at a given voltage (in conditions that allow electron emission from one electrode to the other). For large voltages, the ...
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Finding Magnetic Mirroring Points

I am trying to find the mirroring points of the following magnetic field. $B_z = 2B_0[1+(\frac{z}{L})^2]$ This is problem 3.13 taken from Introduction to Plasma Physics by Donald A. Gurnett (Second Ed....
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How large is the fusion plasma dielectric constant? Why does this mean radial current cannot exist in a tokamak?

I am reading this paper by Rosenbluth and Hinton (1996). In the second paragraph of the introduction, they say two things I don't understand: The first, is that they claim that the "plasma ...
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Radial dependence of temperature of solar wind?

How does the temperature of the solar wind plasma depend upon radial distance from the Sun?
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Electrostatic fields in Plasma

I was studying Plasma physics, when I came across this statement: As a consequence of their high electrical conductivity they do not support electrostatic fields except, to a certain extent, in a ...
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How does a change of reference frame affect a 1D (non-relativistic) electrodynamic analysis?

I am a bit confused as to how to handle the effect of a change of reference frame on a 1D electrodynamic analysis that I am looking at, in relation to a plasma. Say I have an infinite tube containing ...
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If lightning is caused by ionisation of air, why does it only last briefly?

I'm comparing lightning and fire - both are related to ionisation of air but lightning happens so fast in a blink of an eye while fire goes on until it runs out of fuel. My question is: despite being ...
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Why is a magnesium flame changing color in an electromagnetic field?

On YouTube I have seen someone build a RF emitter (probably in the 10 MHz range with about 5000 Watts) and then use it to ignite magnesium strips. Magnesium usually burns with a bright white flame in ...
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Taylor's hypothesis in turbulence

Reading about Taylor's hypothesis for converting spatial to temporal scales and vice-versa, I understand that if $V$ is the bulk speed of the fluid then we could use: $$\ell = V \cdot \tau$$ To ...
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Derivation of dispersion relation of electromagnetic waves in a magnetized hot plasma

I look to solve analytically the Vlasov-Maxwell equations for a magnetized hot plasma $$\frac{\partial f_{s1}}{\partial t}+\vec{v}\cdot\frac{\partial f_{s1}}{\partial \vec{r}}+\frac{q_s}{m_s}\Big(\vec{...
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What is the Fokker-Planck collision operator and how is it derived?

On page 7 of Goldston and Towner (1981) they state that "The Fokker-Planck collision operator for pitch-angle scattering is given by $$\left.\frac{\partial f}{\partial t}\right|_c=\frac{\nu_{ii}}{...
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Work in Debye-Huckel theory

I've seen this passage in the Debye-Huckel theory derivation (for a plasma): $$F=U-TS$$ $$dF=dU-TdS-SdT$$ and substituting $dU=TdS-PdV$ $$dF=-PdV-SdT$$ my question is why $dU=\delta Q + \delta W=Tds-...
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What is the definition of a plasma?

I understand that the conventional definition of a plasma is that the Debye length is much smaller than the size of the plasma, however I can't seem to find what the numerical value of this ratio ...
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At what power of magnetic resonance does metal embedded in a person start to be pulled?

What is the level (number) of magnetic resonance necessary to provide an unsafe environment for a person who has metal embedded in their upper body? At what level do the metal shards start to be ...
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Correct way to estimate trace power spectrum

Assuming that one wants to estimate the trace power spectrum of a field $\vec{B}$ $$\vec{B} = B_{x}\hat{x} + B_{y}\hat{y} +B_{z}\hat{z} $$ Would you have to estimate the PSD of each of the components. ...
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Aurora Borealis

As we know that during a solar flare, a large number of electrons and protons are ejected from the sun. Some of them get trapped in the earth’s magnetic field and move in helical paths along the field ...
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Understanding the behavior of electron two-beam systems | Plasma physics

I am studying the behavior of an electron beam going through plasma. Such particle beam is created by adding equal and opposing velocity drifts $v_0$ to the electron distribution $$v = v_{th} \pm ...
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Quasi-linear theory of plasma, some queries

I was studying about quasi linear theory of plasma turbulene and stuck at some questions (derivations), I could able to derive upto Eq.14 of this paper, but not sure how proceed for deriving the ...
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Theoretical rocket engine based on plasma shock waves particle acceleration

Credits for the article - https://www.quantamagazine.org/cosmic-map-of-ultrahigh-energy-particles-points-to-long-hidden-treasures-20210427 Can this mechanism be used to speed up gas particles to ...
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What is the maximum flux of 1 GeV stably-trapped protons in Jupiter radiation belts?

And in which L-shell? This graph shows a flux of around 50 stably-trapped protons per m2 per sec on Earth, and I have read it's higher in Jupiter but I can't find the value. A source would be ...
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Fluid Mechanics and Plasmas

Can anyone please explain what is difference between movement of a plasma and a fluid.
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Why do gas discharge tubes operate indefinitely?(Or do they?)

Question Can a gas discharge tube with a perfectly sealed glass tube operate indefinitely? Or do the ions get "used up"? Further detail My (limited) understanding of gas discharge tubes is ...
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Landau Damping explained in Landau's book

In the book Physical Kinetics: Volume 10 from Landau it is explained the Landau damping. The author explain the phenomena considering an electron subjected to a small amplitude longitudinal wave and ...
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Plasma with a controlled density?

I want to generate a plasma like this: https://www.youtube.com/watch?v=eTOmJ7tnTQc&ab_channel=GarageLab If I understand correctly, the plasma generated depends on the voltage applied and the ...
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Absorption spectroscopy - transmittance (normalized)

In the absorption spectroscopy we can calculate transmittance $T$ of a given sample by comparing how the intensity of the incident beam $I_{0}$ is decreased with the distance (Lambert-Beer Law). $A = -...
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Are there any plans for cosmic ray detectors as part of the new ARTEMIS program?

NASA's new Artemis program involves building several temporary waypoints around and on the moon. One of the side-bonuses for scientists is that this has opened a few new funding avenues for studying ...
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Is high tempurature/ thermal radiation a requirement for ionization of gas to plasma using different frequencies of photons?

I am wondering if thermal radiation or heat energy is fundamental to ionizing a gas into a plasma when using lasers or different frequencies of light. I know that gas discharge tubes or Geissler tubes ...
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Doubt about the explicit toroidal and poloidal components of a confined plasma in Tokamaks

Introduction Since the magnetic field is solenoidal: $\nabla \cdot \vec{B} = 0$, it is possible to decompose it as: $\vec{B} = \vec{B}_{T} + \vec{B}_{P} \tag{1}$ where $\vec{B}_{T}$ is the Toroidal ...
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What happens in a Plasma when ions and electrons collide?

What happens in Plasma when ions and electrons collide? I know that Plasma is when you have a soup of electrons and ions, which results from a gas being stripped from its electrons. My thinking now ...
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Ionizing a Gas Into Plasma by White Light

I am curious about whether I can use different frequencies of photons to ionize a gas into a plasma without high temperatures or high voltage. The different frequencies of photons would excite the ...
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How is it possible that a collisionless plasma has a more densely populated Debye sphere?

It is well known that for a collisionless plasma, we have: $$ \Lambda = n_e \lambda_{De}^3 \gg 1 $$ which means that the Debye sphere is densely populated. Whereas it is the opposite for a collisional ...
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Plasma effects on CMB

I have been studying plasma physics and how photons acquire a longitudinal polarization when propagating through a plasma. However, I have not found any information about how this affects CMB photons ...
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