# Tag Info

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Broadly speaking, fire is a fast exothermic oxidation reaction. The flame is composed of hot, glowing gases, much like a metal that is heated sufficiently that it begins to glow. The atoms in the flame are a vapor, which is why it has the characteristic wispy quality we associate with fire, as opposed to the more rigid structure we associate with hot metal. ...

13

A brief history of the misapplication of magnetohydrodynamics to the analysis of the solar wind: 1959: Soviet satellite Luna 1 directly observed the solar wind for the first time and measured its strength. http://en.wikipedia.org/wiki/Luna_1 So as of 1959, by direct experimental observation, it was known that the heliopause was at least the radius of the ...

10

Firstly, 'Fire', according to numerous comments and answers [here][1] is a 'process', in which case, the answer to the question will be 'no', since plasma is a state of matter. It would be unfair to leave it there by blaming the semantics, and given the abundant references to 'flame' region, I am going to assume that that is what the question meant to ask. I ...

10

You actually make reference to something which is of crucial importance to the answer to this question: "With a tokamak, I imagine that if you double the linear dimensions, the plasma volume (and hence the power production) will increase eightfold, whereas area that you have to protect against fast neutrons will only quadruple. So once you master the ...

10

Yes, the claims in the video are totally absurd from the viewpoint of science. It's enough to listen for roughly 70 seconds to be sure that the narrator doesn't have the slightest clue about physics and the remaining 302 seconds make this fact even more self-evident. I won't try to answer the question whether the authors of the video realize that what they ...

9

From my cursory overview of the stuff these people have online, there are a few really glaring problems: First and foremost, it doesn't appear that the electric universe model makes any quantitative predictions. I don't see any models for how stars and galaxies are supposed to form and behave, just a bunch of words about how gravitational models make too ...

7

The asymmetry comes from the different masses of electrons and neon ions (neon ions are about 36000 times heavier). This mass asymmetry results in different cross sections for the excitation of neon atoms by electrons and ions. There are some plots of this here http://webhost.ua.ac.be/plasma/pdf_papers/sab97comparison.pdf (figure 1a for electrons, figure ...

7

The big problem with controlled fusion is that the equations governing the plasma are highly non-linear. So each time the physicist increase the size of the Tokamak, new effects are discovered. So I guess that the answer is no-one really knows the correct scaling laws ! This contrasts a lot with fission reactors, where the relevant equations are ...

7

There is a difference between temperature and energy. Plasma is, as you said, very hot - but there isn't very much of it. The density of plasma in the tube is very low. So when it does hit the walls of the tube it transfers very little energy. So the mass of the glass tube increases in temperature only very slightly. It's like a firework sparkler, the ...

6

Plasma is a kind of matter very similar to gas in which atoms have been ionized. It is very hot and lets off radiation (also in the visible spectrum) due to recombination so it might already be considered flame. Thus it isn't clear what "igniting plasma" really means. In cold plasma where only a small fraction (few percent) of atoms have been ionized you ...

6

Ball lightning could definitely be some atmospheric pressure plasma phenomenon. You can make a pretty impressive ball plasma by discharging a kilojoule-scale capacitor bank into a bucket of salt water. Check out Free-Floating Atmospheric Pressure Ball Plasma. In most of those pictures they're using a copper sulfate solution, but that's not essential (sodium ...

6

Electric Conduction: At atmospheric pressure, air and other gases are poor conductors (Insulators) of electricity. 'Cause they don't have any free electrons to carry current. But, once free electrons are produced in gas by ionization (They become plasmas), discharge of electricity through gases appears. This could be done in many ways such as applying large ...

6

You're presumably thinking that vaporised NaCl would consist of Na$^+$ and Cl$^-$ ions, but this isn't what you get. At temperatures just above the boiling point (1413c) you get neutral NaCl molecules and Na$_2$Cl$_2$ dimers, and possibly bigger polymers. Amazingly someone has measured this: see this paper for details (it's behind a paywall I'm afraid but ...

5

Good question! The defining difference is that in a gas the atoms are intact, and in fact are typically bonded into molecules, whereas in a plasma at least some of the electrons separate entirely from their atoms. In other words, particles of a plasma are charged, but particles of a gas are mostly uncharged. So technically, a plasma is not a gas and it ...

5

Plasmas are a common part of the world we live in. The definition of plasma allows them to exist within an environment consisting mostly of bound atoms. A variety of human technology creates plasmas. The type I hear plasma researchers reference most is a simple RF Plasma. This is perhaps the most direct way to use electricity to shake off the electrons ...

5

See Wikipedia for a list of available plasmas over there..! Or have a look below for the chart which shows variation of temperature and electron density in different plasmas..! A quick Googling would've provided the answer. Common examples include Lightning..! The Sun (from Core to Corona) Fluorescent Lights and Neon Signs Nebulae (Luminous Clouds ...

5

As you suggest in your question the contents of the tube are not in thermodynamic equilibrium. At any moment in time there will be a small number of fairly energetic electrons and a large number of low energy neutral gas atoms. The neutral atoms have a temperature of around room temperature. I'm not sure how much sense it makes to assign a temperature to ...

5

Plasma is said to be a distinct phase because it does not observe the usual description and physical laws that are used to describe the usual 3 states of matter, on several counts: Plasma is not in equilibrium. Often it is far from an equilibrium. Therefore, thermodynamics can't be used to explain. Plasma is made of loose particles, but these particles ...

5

For clarity, there is a common misconception about plasma here. Plasma when being introduced for the first time to someone who doesn't know what it is, it is called "The fourth state of matter" which is an inaccurate description of it. Since this term is used for introducing some one to plasma, it is no big deal. When a material changes from a distinct ...

4

Fire is a plasma. There are two kinds of plasmas: hot plasmas relevant to astrophysics or fusion are indeed a mixture of totally ionized gas. In cold plasmas ( northen lights, Neon tubes,flamme) the ionization degree is less than one but the mixture typically exhibit collective behaviour and a zoo of waves one do not encounter in gases. The most famous is ...

4

Fire is a reaction between molecules in gases. It may look as if a piece of wood is burning, but actually the burning happens in gases given off by the wood as it is heated. Burning wood, paper etc is a complicated business, so let's take a relatively simple system like burning the gas in your cooker (assuming you use a gas and not electric oven). Actually ...

4

This video illustrates how a candle flame conducts a high voltage (10,000 volts). Although the ion density is small in a candle flame, they are sufficiently present to conduct electricity.

4

Well you could replace the elections with something else, such as muons. That is essentially what is proposed for this, although in extremely small quantities. Muons in this case replace some electrons, but very very few compared to the total: http://en.wikipedia.org/wiki/Muon-catalyzed_fusion Obviously, this is fraught with difficulties because there is ...

4

There is a description on Wikipedia accompanying this picture that seems to indicate the mottled surface is the leading edge of a compression shock propagating through the air. In particular, it carries the imprint of the irregularities in the casing surrounding the bomb. I am inclined to agree. While I admit there is no scale to indicate what the different ...

4

If you start with a blob of hot plasma in vacuum without any internal structure, the kinetic energy of electrons and ions will be too large in comparison with the energy of EM interaction for such blob to exist in equilibrium, so the plasma will expand rapidly -- like a gas -- at about the speed of individual particles. However, one can form from plasma ...

4

When we treat quantum mechanical objects as if they are particles, this is often referred to as a classical treatment. Intuitively, this is going to be valid based on a simple argument related to the de Broglie wavelength:$$\lambda_{dB} = \sqrt{\dfrac{2 \pi \hbar^2}{m k_B T}}.$$ Most often, when this wavelength is on the order of ...

3

So in short plasma does not burn green in a chemical sense. It can rather be quite colorful as can be seen in this picture from the remains of a supernova explosion: If you have an oxygen plasma for example this can be used to "burn" organic compounds as is often used in the semiconductor industry to clean wafers. The plasma in this case is already at ...

3

Ignition in what sense? Chemical energy is out of the question, because plasma by definition are mostly ions unbound of their electrons, which is needed for chemical binding. Nuclear fusion ignition, well, that is the whole point behind nuclear fusion research. So if someone finds how to "ignite" plasma, it will revolutionize the world, the inventor will ...

3

The problem with using magnetic fields to contain plasma is that the charged particles move at right angles to the field you're applying. This makes it exceedly difficult to contain them. Tokamak reactors manage it by holding the plasma in a loop so that when the particles move at right angles to the field they just go round the loop, but even so current ...

3

You can start with this very brief (13 page) survey by Tim Eastman : A Survey of Plasmas and Their Applications It provides some philosophical perspective and frames the field nicely. The bibliography can help you dive deeper, and probably the first place to turn is reference no. 8, Plasma Physics and Engineering by Fridman and Kennedy. You can read the ...

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