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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80 views

What is the real momentum equation?

I was reading some paper on plasma physics, and when they use the momentum conservation equation (at equilibrium, i.e. $\partial_t=0$), they write: $(1)\qquad m_i \vec{\nabla}\cdot(n_i\vec{u}_i \...
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Would the effects of a Coronal Mass Ejection be magnified in the South Atlantic Anomaly area?

The South Atlantic Anomaly is an area where the Earth's inner Van Allen radiation belt comes closest to the Earth's surface, dipping down to an altitude of 200 kilometres. This causes one of the ...
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41 views

Do high power (W) elecron beams traveling through air have the same “blooming effect” as high power laser beams?

So I am talking about an electron beam where the electrons have sufficient velocity and the beam is intense enough (for example, beam power of at least 1 megawatt) to produce enough energy to ionize ...
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106 views

How to calculate internal partition function for atom

I am writing my own argon plasma simulation code. For the moment I want to get equilibrium composition of argon plasma. I know that to get plasma number density I need to calculate the internal ...
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181 views

Can a plasma ball light up minerals that fluoresce?

I want to know if I could use a plasma ball to light up a UV poster that are typically activated by blacklights. option 1: using light from the globe According to my research it seems that the light ...
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39 views

Do coronal mass ejections and solar flares diffuse over long distances?

I understand that over great distances electromagnetic radiation such as light and lasers would diffuse greatly (much like a shotgun blast). Is this the same case for solar flares? If this is the ...
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88 views

Where to use small and large argument expansion of plasma dispersion function

My question is rather straightforward (at-least that is what I believe :)): In plasma physics we have what is known as plasma dispersion function. There are two approximation under which this ...
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236 views

Specific heat capacity at constant pressure for fully ionized hydrogen plasma

How do we compare specific heat capacity at constant pressure of air to that of fully ionized hydrogen plasma? I was interested to know if Cp will be different inside sun rather than for dry air? Is ...
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How are cages in fusers protected against ion damage?

I have a simple question. Nuclear fusers (like the Farnsworth Hirsh design) use charged cages to accelerate deuterium ions to high enough energies to fuse and produce neutrons and energy. While these ...
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92 views

Confused about the Drude model

I was thinking about the Hall conductivity, when this question popped up. If there is a magnetic field and an electric field perpendicular to it, then a Hall current is generated since the ions have ...
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425 views

Ohmic heating in a fusion plasma

In a microscopic classic picture, ohmic heating occurs due to collisions. Let's start with the simplest case: a cooper wire and a battery that induces a current. Electrons start flowing and the energy ...
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32 views

Electric field in frame corotating with sun

I am studying this paper on the solar wind for a class on MHD, but I am perplexed by the line that precedes equation (5): " But in a perfectly conducting fluid ${\bf v}$ is parallel to ${\bf B}$ in ...
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“Speed sorting” in electric field and inhomogeneous magnetic field?

Let's say you add an electric field to a inhomogeneous magnetic field, oriented as in the picture; what would that lead to? There is a grad B drift upwards in the picture, that the electric field ...
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50 views

Can colliding electron further ionise positive ion?

Imagine positive helium ion with +1 charge,basically a helium atom with one electron missing. What if electron with kinetic energy greater than second ionisation energy of helium hit that positive ...
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42 views

Diffusion equation in energy and magnetic surface coordinates

The isotropic diffusion equation in Cartesian coordinates is $$\frac{\partial f(\mathbf{x},t)}{\partial t}=\nabla[D(f,\mathbf{x})\nabla f(\mathbf{x},t)]$$ Boozer and Kuo‐Petravic (1981) claim that ...
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What is the optimum altitude for tapping atmospheric charge?

The atmosphere appears to have a large potential difference (voltage) in relation to ground. The obvious example is the thunder where this voltage becomes large enough to break the insulator - air. Of ...
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54 views

What's the timescale for the formation of a coronal mass ejection?

How quickly does the sun form and release a coronal mass ejection? If we were watching the right part of the sun closely, how long would it take us to go from "nothing seems to be happening" to "...
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48 views

Ion acoustic waves in a deuterium plasma?

Has anyone ever experimented with inducing ion acoustic waves in a deuterium plasma? Perhaps to observe the phenomenon of Landau damping? Or to heat the plasma for fusion reactions to occur? And, ...
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81 views

Best/Most crafty ways to enhance spectrometer data from a mini-plasma generator?

I'm an undergraduate intern at a government lab specializing in plasma energy and fusion research. I've been assigned an interesting technical project that involves gathering spectrometer data (line ...
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494 views

Why is the top of the aurora red?

When the solar wind is strong enough, the top part of the aurora appears. It is often red: https://commons.wikimedia.org/w/index.php?title=File%3AAurora_Australis.ogv. The aurora is the product of ...
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276 views

Plasma confining with magnetic fields

How is it possible to confine plasma inside a container? I know that plasma consists of a mix of charged particles, electrons, and the positively charged ionized atoms. Researching, I have found out ...
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57 views

Why take macroscopic average of electric field over length scale smaller then the Debye length?

In Landau and Lifshitz volume 10 pg117 the authors say that the electric and magnetic fields $\vec E$ and $\vec B$ are averaged over regions "having dimensions large compared with the distances ...
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Vlasov equation: weak and long-range vs weak or long-range?

Recently I asked this question on why we need long-range interactions for the Vlasov equation – something I now understand. I have also seen several derivations* explain individually why we need long-...
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52 views

What naturally occurred radiations or waves that don't produce any sound at all regardless of frequency and medium?

What naturally occurred radiations or waves that don't produce any sound at all regardless of frequency and medium? In the video below, this person, Donald Gurnett and some other people at University ...
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Do force drifts occur in highly collisional plasmas

I've read on wikipedia that the force drifts of the guiding centers off particles in a magnetic field also occurs in cold plasma. But does it occur in a cold plasma (Partially Ionized ) in which the ...
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58 views

$B$-fields where field lines are parallel have zero magnetic tension?

The magnetic tension of a magnetic field $\vec{B}$ is given by $(\vec{B} \cdot \nabla )\vec{B}$. It is easy to see that a uniform field has zero magnetic tension. My textbook says the magnetic ...
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Physical origin of the hydrodynamic instability?

I know that in plasma waves the kinetic instability is physically caused by more electrons moving slightly faster then the wave then slightly slow and thus proving energy to the wave. There is however ...
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72 views

Temperature of a mixed plasma

I know the temperature, $T$, in $\mathrm{eV}$ and density, $n$, for the three ion components of a chosen plasma, say $\mathrm{O^+}$, $\mathrm{He^{++}}$, and $\mathrm{H^+}$. But I would like to know ...
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129 views

Vlasov equation why “long range” interactions?

In discussions of the Vlasov equation it is often said (e.g. Cercignani, 1988; pg59) that we require rarefied gas with weak, long range interactions. I understand why we need weak interactions (since ...
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429 views

What is the working principle of electric arc lighters?

How do electric arc lighters work? The wikipedia article about this is very short. So I understand that there is a current at low voltage that leaps over air and turns it into plasma, but what then is ...
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100 views

normal modes of a plasma

I am trying to learn plasma physics and it says that the equation: $$ \nabla^2 \mathbf{E}-\nabla(\nabla \cdot \mathbf{E})+\frac{\omega^2}{c^2}\mathbf{\epsilon}\mathbf{E}=0 $$ where $\mathbf{E}$ is ...
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80 views

Ion acoustic wave regime

I am fairly new to plasma physics and am making a project on the Ion Acoustic Wave. We have discussed Landau-damping in a plasma where we took the electrons to have a Maxwellian distribution and ...
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1answer
78 views

Is each level of ionization in a plasma a separate phase?

Plasma is often described as a separate phase of matter. The defining property of plasmas are they they are gases of freely moving charged particles, allowing large scale electric and magnetic ...
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48 views

Can stellar nucleosynthesis processes other than deuterium-lithium, i.e., oxygen-burning, take place in a reactor?

It is known that gravitational confinement and supernovae facilitate the synthesis of heavy nuclides; and, that magnetic confinement is thought to facilitate the deuterium-lithium fusion in human-...
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171 views

Why is electron temperature in plasma higher than ion temperature?

Wikipedia states that The electron temperature of a plasma can be several orders of magnitude higher than the temperature of the neutral species or of the ions. This is a result of two facts. ...
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98 views

Is an electric field a transverse wave not in a vacuum?

According to "Introduction to Plasma Physics and Controlled Fusion 3rd Edition", in discussing electromagnetic waves in a plasma, $\vec{E}$ is said to be a transverse wave. Is $\vec{E}$ a transverse ...
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103 views

What accelerates the solar wind?

The question is in the title. A bit of background info: the escape velocity at the photosphere of the Sun is ~ 620 km/s, but the mean speed of the solar plasma there (inferred from the temperature) ...
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106 views

Drift kinetic equation orderings

I'm trying to derive the first order drift kinetic equation given in the book Collisional Transport in Magnetized Plasmas by P. Helander and D. T. Sigmar, section 6.5. I understand that the ...
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In a plasma, can the ion temperature become larger than the electron temperature?

Let's assume a hydrogen gas, initially at low temperature The density is low enough so that heating of this gas by inverse bremsstrahlung can be neglected. Now if a high-intensity radiation source ...
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Why all the orifices, protuberances, hinged/bolted panels, etc. on a stellarator?

My question was inspired by this one - in particular the image it has (also shown here): Why does the external casing of the Stellarator (in particular, the Wendelstein 7-X shown in the above image) ...
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Incomplete Fermi-Integral to link solid and plasma: Did this autor make a mistake?

At some point int his paper[1] the author defines a function: $$f(T)=\int_\mu^\infty F(\epsilon,T)d\epsilon$$ where $$F(\epsilon)=\frac{g(\epsilon)}{1+e^{(\epsilon-\mu)/kT}} d\epsilon$$ and $$g(\...
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Does light actually travel in a straight line?

Sir Issac Newton said that light travels only in a straight line. But in a burning candle, as flame is in upward direction the light from it does not travels in a straight line; it spreads. What is ...
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67 views

Why is the Paschen Law linear at large pd values?

The Paschen Law becomes linear at larger $p\times d$ values but what's the origin of this linearity? Does it come from the homogeneous electrical field? I understand that the origin is partially due ...
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21 views

Localized electrostatic-acoustic disturbance

From this youtube comment it describes a 'localized electrostatic-acoustic disturbance' as a 'very rapid, sudden static charging of the atmosphere'. I've done some lite searching but haven't found ...
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2k views

What is the physics behind the plasma frequency?

I can't seem to find a satisfactory, intuitive explanation for the way electromagnetic waves behave when they encounter a cold plasma (that is, one where $\omega^2 = \omega_p^2 + c^2 k^2$). My ...
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704 views

What is the critical electron density in a plasma?

In the article Ion Acceleration and D-D Nuclear Fusion in Laser-Generated Plasma from Advanced Deuterated Polyethylene by Lorenzo Torrisi, the author mentions a critical electron density on page 17057....
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285 views

Plasma directly to Solid or Liquid and vise versa

Let's forget how and go straight to the beef and potatoes. What do you scientifically call it when a plasma turns to liquid and skips recombination, and/or condensation? What about when a liquid turns ...
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156 views

What is the physical basis for Pedersen and Hall currents in an atmosphere?

There are three components of a conductivity tensor in atmospheric electrodynamics: the parallel conductivity along the direction of the magnetic field, the Pedersen conductivity (in the direction of ...
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361 views

What is the viscosity of Sun surface?

It should be possible to compute value from hydrodynamics of Solar prominence. What is the current estimate of Solar surface viscosity?
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279 views

Can metals be ionized by radiation?

In gaseous state a laser can ionize metal atoms and create a plasma. But what about the solid state? Is a high intensity laser able to ionize a solid metal?