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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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Are there any substances that exist as plasmas or supercritical fluids at STP?

If not, why If so, please give some examples
Harrychink's user avatar
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Relation between electron temperature and electronic mode of energy for a gas

I have been doing some introductory reading on plasma physics as part of my research, and I am currently trying to understand the concept of electron temperature. Based on my basic understanding, ...
Nikkhil Chander's user avatar
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Does detailed balance apply if electrons and ions have different temperatures

Suppose I have a plasma where the ion temperature $T_i$ is different from the electron temperature $T_e$. Does detailed balance still exist between recombination and ionization?
S.T. Zweig's user avatar
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Can plasmas have eddy currents?

A couple days ago I asked a question on if plasma could have a magnetic field due to current which was a yes. Now I am wondering again on if plasma can possess eddy currents. Assuming a time varying ...
Coolcats112's user avatar
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How would I calculate plasma density profile for a plasma in a magnetic field?

I want to find the density profile of a xenon gas plasma at a given pressure. My current approach is to model the plasma as a fluid and use the continuity equation below: $\frac{\partial n(\vec{r},t)}{...
MXVG's user avatar
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How can I calculate the magnetic field of a plasma?

If I created a plasma and put a large electric current through it would a magnetic field be created? If so how large would this field be and how can I calculate it? For example, we put 1000 amperes ...
Coolcats112's user avatar
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Accuracy of the Higuera-Cary Particle Pusher

UPDATE: 12 July 2024 This question has been answered. Also, I figured out the problem. One of the papers I was referencing (Ripperda et al.) had a typo, which was leading to the errors. The method is ...
Mohammad Yasir's user avatar
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1 answer
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Difference Between Plasma Potential and Floating Potential in a Plasma

I'm learning about Langmuir probes and I'm confused about the difference between the plasma potential $V_p$ and the floating potential $V_f$. From my understanding, when a plasma is in contact with a ...
ReggiePlasmaQs's user avatar
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ELF Electromagnetic wave propagation in plasma (ionosphere) - how?

Can an extremely low-frequency electromagnetic wave (below 500 Hz for example) propagate through an ionosphere? The cutoff frequency of Earth-ionosphere waveguide is approximately 1.7 kHz so I ...
Leif's user avatar
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Derivation of gyrocenter speed in gradient magnetic field, doubt in resolution differential equation with slow time variation force

I was reading Paul M. Bellan's book:"Fundamentals of Plasma Physics. Cambridge University Press, 2006.", the chapter "Drifts in slowly changing arbitrary fields", in particular the ...
Axel Togawa's user avatar
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How can photons be absorbed by matter, without causing ionization or new photons?

Let's say we have a gas, of argon atoms for example. We raise the temperature of the gas to 20,000K. Some atoms collide with enough energy that the atoms ionize, into free electrons and ions. So, now ...
Hugh Perkins's user avatar
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How can a free electron and an ion in a plasma recombine without violating conservation of energy and momentum?

This question is the inverse of How does ionization of gas molecule affect the translational kinetic energy of the molecule? The answer to that question is that a molecule cannot spontaneously ionize: ...
Hugh Perkins's user avatar
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How does ionization of gas molecule affect the translational kinetic energy of the molecule?

Some things I understand to be true: When we raise the temperature of a gas to around 10-20,000 Kelvin, the molecules of gas start to ionize, form a plasma, according to the Saha equation. The ...
Hugh Perkins's user avatar
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How could I calculate the strength of an electromagnetic field sufficient enough to generate plasma in low pressure argon gas?

For context, I wish to create a plasma toroid in a glass sphere of 25 Torr Argon gas like in the photo below; there are multiple examples of how to do this online using a class E oscillator ...
MXVG's user avatar
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What is weakly coupled plasma?

What is meant by weak and strong coupled plasma? What is the way to diagnose it in terms of theory and experiment?
Amirhossein Kian's user avatar
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Can high intensity laser excite surface plasma waves?

As we know, light in free space cannot excite plasma waves. However, it is possible to get help from the prism, grating or surface modification. However, with the help of two high-intensity laser ...
Amirhossein Kian's user avatar
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Derivation of the Coulomb Collision Operator for Plasmas

I am attempting to learn about Coulomb collisions in the kinetic theory of plasmas. In doing so, I have come up with an "intuitive" derivation of a Coulomb collision operator. However, the ...
MeowBlingBling's user avatar
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Mean free path equation for plasma

Does the mean free path equation $$\lambda=\frac{1}{\sqrt{2}\pi d^2 n_v}$$ work for collisions in plasma or just for gas?
Waev's user avatar
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Electric and magnetic field configuration that makes an electron trace the surface of a sphere

Can anyone suggest an electric and magnetic filed configuration that can make an electron trace the surface of a sphere? Has such a configuration been achieved experimentally?
Dr. user44690's user avatar
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Can Muon Catalyzed Fusion work in a Plasma?

From what I understand, muon catalyzed fusion works by injecting muons into the deuterium and tritium, which then they replace the electron shared between the hydrogen isotopes in a molecule, making ...
Barry Allen 's user avatar
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Can the transmutation of hydrogen to heavier isotopes be reversed without the loss of energy. This is transmutation, not fusion [closed]

In a high frequency plasma enriched with hydrogen, the transmutation to heavier H isotopes is; (n=neutron. p=proton. e=electron. E=energy) n + p = Deuterium + E out. D + p = Helium + E out. ...
gaia's user avatar
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Can X-rays compress plasma for fusion?

I know in ICF fusion, generally lasers are used to generate X-rays inside a holhraum to compress a duetirium tritium fuel pellet until it generates fusion reactions. I was wondering if the same ...
Barry Allen 's user avatar
5 votes
2 answers
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Is it possible to predict the appearance of auroras?

Yesterday I saw online a lot of people seeing auroras both in the North and in the South of the globe. Unfortunately, I wasn't one of these people, and this got me curious about how much we can ...
Níckolas Alves's user avatar
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1 answer
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Ozoneless air ionisation

Is there some way to ionise air in way that removes or atleast decreases ozone production? Is some combination of electrode shape, electrode material, negative or positive voltage, dc or ac and ...
wav scientist's user avatar
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How to calculate dissociation rate of molecular hydrogen ion?

Suppose I have a positive molecular hydrogen ion in a bath of electrons with a temperature $T$. How do I calculate the dissociation rate of the molecule due to electron impact? Should I just use Fermi'...
S.T. Zweig's user avatar
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Temperature of plasma sputtering magnetron

This question is in regards to DC magnetron sputtering for coating surfaces. My main goal is to determine how much heat will be seen by the anode, cathode and the target. As well as to determine what ...
CakeMaster's user avatar
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Highly relativistic electron scattering in thin plasma

I am curious about how extremely relativistic electrons (10s of GeVs to single TeVs) scatter when going through the interplanetary and interstellar medium, which is a thin plasma. I have read about ...
cthon's user avatar
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Does the Saha Equation Still Apply if Ions are added Artificially

Suppose I have a hydrogen plasma where some of the electrons have been removed or additional ions have been introduced so the gas has a net non-zero charge density. Would the Saha equation still apply ...
S.T. Zweig's user avatar
1 vote
3 answers
46 views

Question about the use of the term 'mode' vs 'instability' in fusion experiments

I am currently trying to get to grips with MHD instabilities in fusion experiments, and I am confused at to why instabilities are sometimes referred to as modes? To my understanding, a 'mode' is a ...
matrixender's user avatar
2 votes
0 answers
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How can I derive the Bohm criterion for two ion species?

I reviewed many literatures said that if we have plasma with multicomponent species. The plasma contacted with solid surface can satisfy Bohm criterion that \begin{align*} \sum_{is=1}^{n} \frac{n_{is}...
xox_xox's user avatar
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3 answers
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What is the temperature at which plasma (the fourth state of matter) forms?

I wanted to know at what temperature plasma is formed? And what is its average temperature? If possible, explain very simply.
Samyar's user avatar
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Dispersion Relations in a Cold, Unmagnetized, Collision-less Plasma

Currently I am trying to understand the physics of waves in cold plasmas. So in a cold, collison-less, unmagnetized plasma you can derive two different different dispersion relations: one for ...
ReggiePlasmaQs's user avatar
1 vote
1 answer
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How to create a spectral image from a gas?

Let's say I want to put air through an optical spectrometer. It doesn't need to be NASA accurate, but suppose I just want a rudimentary measure of carbon from the carbon frequencies. How can I get &...
CaptainCodeman's user avatar
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1 answer
30 views

Does an electric arc formed in air create more heat than in neon or argon?

When you create an arc in the air it becomes several thousand degrees and is hot enough to weld with. However, plasma arcs in neon/argon are cool to the touch, and are used for neon lighting and small ...
CaptainCodeman's user avatar
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7 views

Conservation of Magnetic Flux and vorticity in astrophysical plasmas

I have a doubt about the conservation of magnetic flux in astrophysical plasmas, in particular in the presence of turbulent motions and vorticity (surely due to poor understanding of vector identities)...
Marco Leonardi's user avatar
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How can the magnetic mirror force act along B direction if it is derived from $q\vec{v} \times \vec{B}$ force?

A typical derivation of the magnetic mirror force of a charged particle in a magnetic field such as from Nicholson (1983) pg 26 uses the $q \vec{v} \times \vec{B}$ force, conservation of the dipole ...
E. Nerney's user avatar
1 vote
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31 views

Ideal MHD energy transfer

Consider ideal MHD: infinite conductivity, frozen-in magnetic field lines etc. Clearly total energy of the system is conserved (magnetic field energy + plasma internal energy + kinetic energy = const)....
Alexander's user avatar
4 votes
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57 views

Why do some nuclear tests feature what seems to be an additional fireball on top?

Have a look at this frame from footage recorded during Operation Hardtack I - Test POPLAR Clearly the bit on top is extra hot, and it seems to be above the main fireball, or at least not part of the ...
user3371024's user avatar
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Potential Perturbation of the Ionosphere by Artificial Re-entry Plasma Dust

Recently I read on Spaceweather.com https://spaceweatherarchive.com/2024/02/ a surprising paper according to which the space debris or vaporized material (mostly metals) that has been deposited in ...
Cisfinite's user avatar
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1 vote
1 answer
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Definition of injection spectrum of an electron beam

Referring to Plasma Astrophysics, Part 1, Eq 4.32, The number density of electrons in the beam at a distance $z$ from the injection plane at $z = 0$ is defined as, $$ n_b(z) = \int_{0}^{\infty} \int_{...
Refrigerator's user avatar
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How can I determine sound speed of ions in plasma sheath

Since the definition of sound speed, ($c_{s}$), in each ion s$th$ species ($is$) expressed that: \begin{align*} c_{s,is} = \sqrt{\frac{k(T_{e}+T_{is})}{m_{is}}}. \end{align*} How can we determine ...
nirama_xox's user avatar
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30 views

Dimensionless non-relativistic energy of fast particles

In Plasma Astrophysics, Part 1, Equation (4.7) the dimensionless non-relativistic energy of fast particles ($m$) in a plasma with electrons ($m_e$) and protons ($m_p$) is defined as, $$ x = \frac{m v^...
Refrigerator's user avatar
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Derivation of kinetic equation for fast particles in a plasma

Referring to Plasma Astrophysics, Part 1, author: Boris V Somov, 4.1.1, We have the kinetic equation with Landau collisional integral, $$ \frac{\partial f}{\partial t} + v_{\alpha} \frac{\partial f}{\...
Refrigerator's user avatar
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Is there a ponderomotive force due to a traveling wave?

Imagine a traveling, EM wave passing through some plasma. The waveform is given by the vector potential: $A = (0, -\frac{cE_0}{\omega_0}\cos\eta, 0)$ where $\eta = \omega_0t-k_0x$ is the phase. From ...
Razor's user avatar
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Dynamic of Alfvén waves in a hot magnetized plasma

I'm trying to derive the dispersion relation of Alfvén waves (AW) by solving analytically the Vlasov-Maxwell equations for a magnetized hot plasma but I'm confused. A simple question, to treat AW ...
Gallagher's user avatar
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Can you have two different Bohm velocities within a multispecies plasma?

How would you calculate 2 different bohm velocities in a multi species plasma, say H+ and N gas excited by a microwave reactor.
fermionicplants's user avatar
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Muon-catalyzed fusion: muon number

I recently read a paper "Meson-catalyzed fusion in ultradense plasmas" (it is behind a paywall: only subscribers to Physical Reviews E can read it) that claims that muon-catalyzed fusion in ...
S.T. Zweig's user avatar
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1 answer
76 views

Validity of equation for $E \times B$ drift in SI and Gaussian unit systems

I derive $E \times B$ drift $\vec v_{E \times B} = \dfrac{\vec E \times \vec B}{B^2}$ and in SI I use V/m and T for the fields. I do not use Gaussian (cgs) units often, but I thought this equation ...
Paweł J's user avatar
2 votes
1 answer
138 views

How to convert from momentum to energy distribution? (relativistic electrons)

I am using a gyro-kinetic simulation tool 2103.16457 which solves the 3D Fokker-Planck equation for the electron population in tokamak plasmas and evolves plasma parameters self-consistently. In many ...
Ferenc Lengyel's user avatar
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3 answers
79 views

Can plasma be made dense enough to the point of acting like a solid without reaching extreme temperatures. Such as a cold plasma behaving in this way

Could a cold plasma be densified until its particles are so densely packed together that it behaves like a solid without reaching extreme temperatures? If so how? Edit: okay there seems to be a ...
Ink's user avatar
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