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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152 views

Plane waves in plasmas

Waves in plasmas can be classified as electromagnetic or electrostatic according to whether or not there is an oscillating magnetic field. A corresponding wiki article states: Applying Faraday's ...
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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 ...
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20 views

Criteria for electrostatic approximation in microscopic/kinetic plasmas

I started pondering about the electrostatic approximation in relation to plasmas, where a particle's motion $\mathbf x(t)$ is governed by the Lorentz force: $$ m\ddot{\mathbf x}=q(\mathbf E+\dot{\...
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25 views

Discrepancy when using Saha equation?

I was trying to calculate the level of ionization using Saha eq. for hydrogen gas at 1 atm pressure at 10 000 K and upwards. I used an Excel spreadsheet and the values I get don't match with other ...
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What is causing plasma confinement instability according to Erik Witalis?

Erik Witalis mentions problems with traditional plasma confinement like the one in tokamaks and particle beams. Instead he mentioned a different technique. What is the problem with plasma confinement ...
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How much energy does it take to form a plasma channel with a laser?

The usage is for something like this https://en.wikipedia.org/wiki/Electrolaser I know that the laser is powered for an instant in which a plasma channel is formed for the electricity to flow through,...
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How hot is a laser beam going to be when strong enough to create a plasma channel? [on hold]

The type of laser I'm referring to comes from here: https://en.wikipedia.org/wiki/Electrolaser Would an extended use of it be able to burn stuff?
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65 views

Lasers for plasma

Recently I had the same idea as given at A question about the properties of plasma and its potential use in recycling, or a similar one, rather. The basic idea is: could you turn stuff into plasma ...
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77 views

Why the geomagnetic field become stronger when solar wind is stronger?

The following description is from the webpage of Niels Bohr Institue's Former Centre for Ice and Climate The Earth reacts to the solar wind by increasing the strength of the shielding magnetic ...
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Could ball lightening be a form of plasma?

With regard to the recent arXiv article: J. D. Shelton, Eddy Current Model of Ball Lightening http://arxiv.org/abs/1102.1224 I wonder if this is a reasonable explanation of ball lightening, or if ...
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Magnetic compression of plasma?

What is the mechanism for plasma compression in the video below? I provide a still from the video and a link to the actual video on YouTube. https://www.youtube.com/watch?v=gsjWGz3YE5o BTW, is ...
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How is the gyrating motion of a charged particle in a non uniform magnetic field?

In a uniform magnetic field it is simply a circle in 2D(x,y) and a helix with constant pitch in 3D(x,y,t). How does this change when the magnetic field is not uniform ? For reference : $\mathbf B = ...
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How is the electron (&ion) temperature measured in plasmas using Langmuir probes?

I want to know the concept behind the temperature measurement and what exactly the "probe" does apart from introducing potential in the plasma. Also, while deriving an expression for electron ...
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How do we find the equation for the gyrating motion of a particle in a uniform magnetic field and a non-uniform Electric field? [closed]

Considering the gyrating motion is not negligible and also retaining the guiding center drift, how do we get the trajectories x(t),y(t),z(t) of the particle? In this case is the variation in the ...
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60 views

Electric field of electron in alternating potential

I am considering the case of an electron placed in an alternating sinusoidal potential, of frequency 13.56 MHz (frequency typically used for RF plasma generation). Suppose I have a simple 1D set up, ...
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143 views

What is meant by “collective behavior” in the definition of plasma?

"Plasmas are many-body systems, with enough mobile charged particles to cause some collective behavior ." [M.S. Murillo and J.C.Weisheit Physics Reports 302, 1-65 (1998)]. In the above definition ...
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Material heating from AC electromagnet

What material property decides how much will that material heat up when inside solenoid with alternating current applied to it? I am trying to research what type of ceramic will absorb as little ...
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What is the equation for the gyrating motion of a particle in non-uniform magnetic field?

Consider a magnetic field B = Bo($1+x^2$) where Bo is a constant. And B is in the z-direction. All the standard textbooks on Plasma Physics seem to skip over this part and only consider the guiding ...
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181 views

Joule heating for a fluid

Say you have a conductive liquid with a changing magnetic field going right through it, causing an electric current. How exactly does the electric current travel and how could you calculate the ...
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Question about spatial uniformity of particle density in plasmas (from Bellan)

Early in Bellan he asks us to consider a finite-temperature plasma and assume that the ion and electron densities are initially equal and spatially uniform. He approaches the problem of calculating ...
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Mathematical form of distribution function with high energetic beam

Maxwell Boltzmann distribution function (MBDF) has the form $$f(v)=n(\frac{m}{2\pi k_BT})^{\frac{3}{2}} exp(-\frac{mv^2}{2k_BT})$$ [Basic Space Plasma Physics by Rudolf A. Treumann & Wolfgang ...
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30 views

Temperature anisotropy in plasmas

If a species of a plasma is described by a distribution function $f(\mathbf{r},\mathbf{v},t)$, is it possible to have different temperature (thermal energy) values for different directions (x, y and z)...
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Problem while constructing langmuir probe

I am working on DC glow discharges and want to construct a langmuir probe. Circuit I am using is as shown in the picture Also, I am applying ~1KV across cathode and anode. Problem I am facing is that ...
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Is a dipole fusion reactor feasible?

It is well known that the earth's dipole-like magnetic field is able to confine charged particles to paths that spiral along the field lines. That's why we have auroras and the Van Allen radiation ...
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163 views

Special conditions at layer F2 ionosphere

I saw this graph about the electrons density in different altitudes and difference between night and day, the difference between the 2 electron densities (day and night) decreases till 300 Km (F2 ...
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187 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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395 views

What is the difference between granulation and supergranulation in the Sun's photosphere?

Granulation and super granulation seem to be some sort confused topics as they are due to the heated particles coming out of the surface. What is the difference between the two?
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Air ionisation through insulated conductor

Imagine electric conductor,copper wire for example,that is fully coated with thin teflon coating and this coated wire is surrounded by air. The classis high voltage air ionisation happens when the ...
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What Debye length should be used in plasma?

In short Which expression should be used: (1) or (2)? At length Definition of the Debye length $r_D$ is following: $$r_D=\left( \sum_{j}\frac{4\pi q_j^2 n_j}{kT_j} \right)^{-\frac{1}{2}}$$ It is ...
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Does density of states at Fermi level reduce or increase for decreasing the diameter of a nanowire?

As we decrease the diameter of a nano wire /quantum wire, does the density of the states at Fermi level increase or decrease?. If it does then, Why?
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Is there a “pinch effect” in a Tokamak?

Is there a "pinch effect" in a Tokamak, like in a linear Z-pinch or in a circular pinch (the ZETA machine from the late 50's)? Tokamaks run in a pulsed mode and a powerful circular current is induced ...
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29 views

Glow discharge : Why is the voltage stable with increasing current in the normal glow mode?

In the characteristics shown, the normal glow mode is from F to G, the voltage is stable with increasing current. I understand the explanation of how the electrode current density stays constant(the ...
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273 views

Questions about plasma

Imagine if you were to heat liquid mercury until it reaches a plasma state. Would it be possible to completely separate the free electrons (ions) from the positively charged nuclei (cations)? Next, ...
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182 views

Landau's approach to collisions in plasma

I can't understand some steps in obtaining the collision term in the Boltzmann equation for plasma. For the first time it was made by L.D. Landau in his article "The kinetic equation in the case of ...
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278 views

Why induction coupled plasma use RF frequencies?

The frequency I see all the time is 13.56mhz,I understand that when you want to make heat treatment surface finish on steel,you use high frequency in the heating coil so the skin effect heats only the ...
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158 views

How to classifies the distinct “plasma” phases of matter?

How to classifies the distinct "plasma" phases of matter? and What theory classifies the distinct "plasma" phases of matter? According to Wikipedia: Plasma (from Greek πλάσμα, "anything ...
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225 views

How much of the Solar convection zone is completely ionized?

I was reading about the energy transportation in stars here, and I found this: "The outer portion of solar mass stars is cool enough that hydrogen is neutral and thus opaque to ultraviolet photons, so ...
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186 views

Spectrum of discharge of air

Where do the various colors in electrical discharge of air with a high voltage originate from? Are these transitions in ionized nitrogen gas or unionized gas? Are chemical reactions involved? I assume ...
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33 views

Electron equations of motion for plasma

I'm reading through an Introduction to Plasma Physics by Francis F. Chen, and in the simplified derivation for plasma oscillation in 1D, the book quotes the electron equations of motion as: $$mn_e\...
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138 views

RF-sputtering: where comes the target self-bias voltage from?

While learning for an exam, I stumbled over the following Question: According to Material Science of thin Films by Milton Ohring, "RF sputtering essentially works because the target self-biases ...
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619 views

Radio wave propagation in ionosphere

Radio communication is based on the concept that a radio signal incident on the ionosphere is reflected if the frequency of the wave matches the plasma frequency. But what exactly happens? Is it ...
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109 views

What is the mean ionospheric height?

I am reading some articles about the ionosphere and I am a little bit confused about the terms mean ionospheric height and effective height of the ionosphere. Are these the same thing? I would refer ...
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260 views

Why can xenon gas stay ionised after the “trigger voltage” is removed?

From my understanding of a Xenon flash circuit, a storage capacitor and a trigger capacitor are charged up to about 240V (both with similar RC values, but less capacitance is needed for the trigger ...
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Are / Why are the H II regions positively charged?

One of the questions in our recent astrophysics course homework was to find the general opacity $\kappa$ of H II regions. We know that the H II regions are almost entirely ionized hydrogen and I ...
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34 views

What are the prerequisites for a free electron and an atom/ion to recombine?

I'm mostly interested about recombination not in plasma (e.g., recombination of beta particles with atoms that they pass by), although the rules are probably the same. Say, there's a free electron ...
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235 views

Units in Plasma Physics

What are the units people use in plasma physics? I am having hard time converting an equation from an old paper to SI units. I saw temperature being defined in $eV$. I assume this is $eV/k_B$ with $...
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512 views

The behavior of an ionized gas in an electric field

Say, I have a gas and then I ionize it (provide enough energy for the electrons to escape the nucleus' potential).And there exists, a SLIGHTLY positively charged surface beside the gas. Now, will the ...
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290 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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Why can’t you see at the start of the Big Bang?

I’m quite confused with regards to photon emission throughout the creation of the universe. From what I’ve heard, there was no light (of any frequency) in the universe until 300,000 years after the ...
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Plasma Cyclotron Heating Textbook

I'm thinking of doing an independent reading course on the subject of cyclotron heating of plasmas, and I've love to hear any textbook recommendations. So far I've only found Gareth Guest's book, ...