Questions tagged [plasma-physics]

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

The critical conditions necessary for a medium containing charged particles to be considered a plasma are:

  • the collection of particles in a given volume, typically a Debye sphere, exhibit a collective fluid-like behavior;
  • the Debye length be much smaller than the system size (i.e., avoid boundary/edge effects); and
  • the plasma frequency be much larger than the collision rate between electrons and neutral particles.

Wikipedia has a rather large list of topics related to plasmas.

When to Use this Tag

covers the physical description of plasmas (ionized media). It should be distinguished from . It can be combined with other tags such as or to specify what type of plasmas are involved.

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How is a plasma different from a metal or an ionized gas?

I've just started looking at plasmas and I have some confusion. A metal is a lattice of positive ions bathed in a sea of delocalised electrons and conducts electricity. A plasma is a 'gas' of free ions and electrons and can also conduct electricity.…
Jabeaumes
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What's the relationship between glow and arc discharge?

I'm trying to understand the differences between an arc and glow discharge. Most texts I have found on the Internet only describes the observed differences but doesn't really explain what happens on the atomic level in the two types of the…
Calmarius
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Would it be possible to have an electron-less solid?

We can create plasmas quite easily, indeed you can buy a plasma cutter and generate it all day long for less than $500. Would it be possible to trap a plasma, say magnetically, and cool it so much that it became a solid/liquid/gas without allowing…
Ehryk
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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 plasma, where the Debye sphere is sparsely…
D. Soul
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Collisionless Plasma Assumptions

When can I assume that plasma is collisionless? How is the presumption of a plasma being "collisionless" depend on other parameters such as ion density and ion and electron temperature?
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Is green superheated plasma possible?

I've noticed that video games like Fallout 4 depict the plasma fired from plasma weapons as green. Is there a way hot plasma can look green in real life? I know some gases emit green light when ionized by a current, but is there any other way?
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Can Plasma Ignite?

This question on Scifi.se: Why does warp plasma burn green? mentions a fictional type of plasma called 'Warp Plasma' that is capable of igniting and when it does it sprays plasma flames/gas out of pipes as if it were oil or some other form of…
Kalamane
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Minimum number of interacting particles to form a plasma

After reading this question https://physics.stackexchange.com/questions/82486/what-is-the-minimum-number-of-electrons-necessary-to-propagate-a-plasmon I began to wonder what is the minimum number of particles needed to have a plasma? I figure that…
Anode
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What is this anode discolouration in plasma tube?

I made a argon plasma tube with 954 bronze aluminum bronze electrodes. After running for some time the anode (left) face is a silver colour. The cathode is on the right. Does anyone know what this is? Is a deposit of some kind? Or has some reaction…
DKNguyen
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How is a plasma with only nuclei and electrons different?

How is a plasma with only bare nuclei and electrons, different from a plasma where the positive ions have some electrons attached? I have looked in plasma physics books but never seen any mention of this. The behavior of a bare proton in a plasma…
Sven _Andersson
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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 plasma-globe and other applications. Do all these…
anon
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Why in plasma physics usually is given the refractive index of electrons but not for ions?

What is the refraction index of ions in plasma ? And why people do not discuss it in books ? Is it that it is not important for plasma phenomena ?
Anonymous
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Why are low m,n modes more dominant?

Consider an axially symmetric, toroidal, magnetized plasma with some safety factor (q) profile. A flux surface has q=m/n where m is the number of toroidal transits and n is the number of poloidal transits for a magnetic field line. Why do the…
cpc333
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Why do the high curvature bends in CFLs have their phosphor coating erode?

I have this pretty old compact fluorescent (CFL) bulb from several years ago still going strong. There was a period where the bulb sat unused when I moved away from home and put the lamp in storage. I'm using it again now and noticed that at the…
jxramos
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Using a Plasma Globe to generate real random numbers

I have been thinking how to easily generate real random numbers when I cam across the small USB-powered Plasma globe. My idea would be to place it in front of an light sensor and read the sensor's values with an Arduino microcontroller. Does this…
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