Theory, lab and space experiments, and calculations related the physics of [plasmas](https://en.wikipedia.org/wiki/Plasma_(physics)), i.e., matter constituted by [ionized atoms](https://en.wikipedia.org/wiki/Ion).

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Is fire plasma?

Is Fire a Plasma? If not, what is it then? If yes why, don't we teach kids this basic example? UPDATE: I probably meant a regular commonplace fire of the usual temperature. That should simplify ...
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3answers
461 views

Liouville's Theorem and Boltzmann equation for plasma

The Boltzmann equation for a plasma can be thought of as coming from a continuity equation in the 6 dimensional phase space of the plasma with coordinates $\left\{x,y,z,v_x,v_y,v_z \right\}$. So ...
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2k views

Possible colors of fire?

I have learnt that depending on the various gases those are involved in the reaction that produces fire, different colors (yellow, red or blue) of flames become visible. I have a question .. what are ...
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4answers
1k views

Conserved quantities and total derivatives?

I am having a bit of a crisis in understanding of the physical meanings of total derivatives. When a quantity $\rho$ (be it a vector or a scalar) is said to be conserved, then (mathematically) ...
4
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2answers
65 views

A question about the Fermi acceleration

In high school physics, we know that a charged particle cannot gain energy from a magnetic field. But, it seems that in the so-called Fermi acceleration, the particle is accelerated by the magnetic ...
6
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2answers
563 views

Difference between irreversible and entropy?

Cedric Villani recently wrote an article on Landau damping, where at least one topic discussed confused me. Besides discussing the issue of how a process can be microscopically reversible and ...
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2k views

Is a plasma a distinct phase of matter?

Long ago I learned that a plasma was a distinct state of matter after solid, liquid and gas, and also that it was achieved by imparting heat to a the matter. But most references describe a plasma as ...
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3answers
22k views

What's the difference between gas and plasma?

A friend stated that stars are hot balls of gas, however we know that technically stars are plasma. Is his statement entirely incorrect? Can a plasma be considered a form of gas or should be referred ...
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Why do we deal only with large scale magnetic fields in astrophysics, and not electric fields?

In astrophysics there is a lot going on about strong, large scale magnetic fields: in stars (prominences), magnetic dynamos, compact accretors collimating jets, etc. There's even a special ...
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2answers
715 views

How large can you make a tokamak?

I've seen questions on how small you can make a tokamak. But I haven't yet seen any "physical" upper limit on the tokamak design. If you take a wind turbine for example, doubling the linear ...
9
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2answers
771 views

Do stars remain electrically neutral? [duplicate]

How electrically neutral do stars remain through their lifetime? As an example, I could imagine processes such as coronal mass ejections leaving the Sun in a slightly charged state. Are there such ...
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4answers
8k views

Does Fire Conduct Electricity? Why?

Recently, I have stumbled upon a YouTube video by Veritasium describing the conductivity of fire. My question is: how exactly does fire conduct electricity? I am a high school student; therefore ...
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2answers
421 views

How does the sun's surface conduct thermal energy from the convective zone to the corona?

How does the surface of the photosphere conduct thermal energy from the convective zone to the corona, while remaining at such a relatively low temperature itself? It seems odd to me that the ...
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3answers
398 views

Why were space physicists wrong about the location of the heliopause?

The heliopause is now estimated to be something around 100 AU (1 AU = Astronomical unit = about the earth sun distance). See the wikipedia article: http://en.wikipedia.org/wiki/Heliosphere From ...
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13k views

What causes fluorescent light bulb to light up when it is near a plasma globe? Can this phenomenon be used to generate electricity in a circuit?

When a fluorescent light bulb is placed near a plasma globe, despite the fact there isn't a closed circuit, a part of the light blulb would light up. I tried measuring the voltage of the air ...
8
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3answers
254 views

Jupiter radiation belt: where >MeV particles comes from?

When I read some discussion about exploration of Jupiter moons, or possibility of life there, a common argument is high dose of radiation in Jupiter's radiation belt (several orders of magnitude ...
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1answer
9k views

How to debunk 'The Electric Universe'? [closed]

My father is a generally intelligent person, however he has latched onto a theory which I believe to be completely incorrect. He doesn't believe in gravity, but rather subscribes to an 'Electrical ...
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1answer
179 views

Inert Gases in Plasma Balls

Recently I have been reading about the fourth state of matter, viz.Plasma. Everywhere I read that plasma is formed when Gases are given enough energy and they lose their electrons to form a "cloud" of ...
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4answers
26k views

Transverse Magnetic (TM) and Transverse Electric (TE) modes

I'm reading and working my way through "Plasmonics Fundamentals" by Stefan Maier and I've come across a step in the workings that I'm struggling to understand when working out the electromagnetic ...
6
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1answer
641 views

What causes the structure visible in first few milliseconds of a nuclear explosion?

Following on from this question, here is a high-speed photograph of a nuclear explosion, taken about 1 ms after detonation: (source) As anna v pointed out, several similar images can be seen in a ...
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2answers
558 views

Dielectric tensor vs. conductivity tensor in (cold) plasmas

I'm studying Waves in Cold plasmas right now, but I guess my question is generalizable. It's about the 4th Maxwell Equation in polarizable / conductive media: $\nabla \times H = \frac{1}{c} ...
4
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1answer
2k views

What is non-thermal plasma?

I read about non-thermal plasma, but I still have some questions: The ions and neutral particles are not in thermal equilibrium with the electron, does that mean that the overall temperature is low ...
2
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1answer
170 views

Reference request for the terminology and usage of different types of plasmas

I'm looking into discharge models, specifically for combustion prcesses, and I'm swamped by the number of different types of plasmas and their respective treatments (thermal plasmas, non-thermal ...
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1answer
81 views

What is meant by infinite wavelength?

1#When an electromagnetic wave propagates in a plasma, with increase in plasma density the phase velocity ($v=\frac{\omega}{k}$) of wave increases. So at cut-off point $k=0$, and phase velocity ...
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How hot can plasma get?

I remember reading about an experiment where fine rods of tungsten were super-heated with millions of amps of electricity, melting them into ionised gas and were then compressed (by magnetic fields?) ...
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1answer
438 views

What's the difference between “Ohmic dissipation”, “Joule heating”, “ion drag” and “resistive heating”?

The following terms are sometimes used to refer to ... more or less ... the same thing by different people and in different contexts (electronic circuits vs. plasma physics, etc.): Ohmic ...
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95 views

What defines a cold plasma?

Been looking for this very simple answer for a while now, and google returns a face cream with the words cold plasma in it. Very frustrated. Just wondering, what constitutes a cold plasma in the ...
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1answer
267 views

Maxwell-Boltzmann distribution for transport equations

I have to calculate the transport coefficients for the Maxwell-Boltzmann distribution. But I'm not sure what distribution I have to use. As far as I know it should not be the MB distribution for ...
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1answer
151 views

What does a sample of the Sun look like? Does it look like fire or gas?

Suppose that in the future a highly resistant spacecraft went to the Sun and collected three samples of the Sun: one from its surface, one from its core, and one midway. The three samples were put ...
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Where on Earth can you find plasma?

Ok, so not that 'where on earth', like literally - 'Where on Earth'. Where on Earth, can you find matter in the 4th state, i.e. the plasma state?
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1answer
209 views

Why is a stellarator-type nuclear fusion reactor so oddly-shaped?

My first impression: It's a mess. Why is it shaped like that? I can't find any info about its shape other than it's a special arrangement of magnetic coils. (link) Here's some more images of it on ...
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3answers
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Is there a phase transition between a gas and plasma?

Does a phase transition occur as a gas is heated to create a plasma? If so, is this a first or second order phase transition? Also, does the presence of a phase transition depend on the pressure or ...
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2answers
3k views

Can low temperature plasma exist?

Plasma is ionized gas which as far as I know only occurs at high temperatures. When plasma cools down it tends to recombine with the electrons present and turn back into gas. But what if the ...
3
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3answers
344 views

Why do many books say quasineutrality is needed for a plasma to exist?

Many books on plasma physics (Chen, Goldston, Lieberman) say that quasineutrality must be satisfied for the matter in question to be a plasma. Yet, we know that non-neutral plasmas exist. So why do so ...
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2answers
335 views

Pressures Necessary for Carbon Detonation

Carbon detonation is a characteristic event of Type 1a Supernova (EDIT: where an accreting white dwarf near the Chandrashankar limit of 1.4 solar masses explodes), an extremely important standard ...
2
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1answer
70 views

Electron beam in magnetic field - increase or decrease the field?

When I fire an electron beam into homogenous magnetic field ( eg. inside Helmholtz coil ) it will bend into a circle => it will form a coil ( = current loop ) itself. The magnetic field created by ...
2
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2answers
532 views

Is NaCl vapour plasma?

Yesterday I asked a question at Chemistry SE, which is if the molten NaCl molecules have enough energy to break into free moving ions, won't be the Na Cl vapor contain free moving ions? So, I've got ...
2
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3answers
529 views

Plasma and Plasma Globes

Plasma is the fourth state of matter. Wikipedia says, that all the gaseous atoms will be ionized into positive ions and free electrons at extremely high temperatures. But, what does this explain in a ...
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638 views

Why is quasineutrality required for a gas to turn into a plasma?

Why is quasineutrality a required condition for a plasma to exist? Quasineutrality means that no density of electrons and ions should almost be equal but not exactly equal. Can anybody explain this ...