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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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What operating range is the ponderomotive approximation valid?

Recalling the equation on the ponderomotive force experienced by a particle in a non-uniform oscillating electric field: $$ F = \frac{q^{2}}{4 \ m \ \omega^{2}} \nabla E^{2} $$ Could anyone shed ...
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213 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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231 views

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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Plasma Frequency of Indium Tin Oxide

What does determine the plasma frequency? The formula is: $$\omega_p² = \frac{4 \pi N e²}{m}$$ and for frequencies above the plasma frequency the material is transparent. So for indium tin oxide (...
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Can plasma be cooled without turning back into a gas, liquid or solid

I’m trying to construct a theory on if the plasma sword in the halo universe would be possible in the real world. So basically what the plasma sword is it is plasma sculpted into a sword shape by a ...
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Why do tokamaks have so few toroidal field magnets?

From the ITER webpage itself, the tokamak has only eighteen toroidal field magnets. If the magnetic field is directly and linearly dependant on the number of coils around the torus, then why did the ...
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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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What shapes could we theoretically make a plasma window? [closed]

I have been reading up on the plasma window, originally discovered by Ady Hershcovitch. A copy of his original paper can be found here. Essentially it has been shown that plasma arcs can be used to ...
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Boltzmann distribution of electrons at thermal equilibrium in a plasma

In Chen's Introduction to Plasma Physics and Controlled Fusion, it says the following during the discussion of Debye shielding: However the last equation tells me that the electron density $n_e$ will ...
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Plasma Flow Direction

How can plasma flow be directed? I’m having a hard time figuring it out this could be done considering the opposing polarities of the ions and the electrons.
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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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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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How can increasing the speed and/or mass of a particle reduce, not increase, it's frequency?

In a Physics World article called 'Neutrons on a Lab Bench', from 30 January 2013, it says, '...Yin and Albright calculated that a very intense laser beam should be able to boost the speed of ...
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One Atmosphere Uniform Glow Discharge

One Atmosphere Uniform Glow Discharge Plasmas are created by simple apparatus and well known high voltage electronic circuits. The electronically generated plasma is sometimes used to disinfect ...
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How does the strong force work in plasma?

For a very long time I have thought of inter-elemental conversion, like lead to gold, or just separating the components of one element to create another. From my understanding, you could overpower the ...
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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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Plasma From Metals

Is it possible to create a dense gaseous plasma from Metals like aluminium, iron etc... using things like Z Pinches? If yes, what would be the efficiency of the process? In a cylindrical array Z ...
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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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What causes the vertical bands of light in an aurora?

I was lucky enough to witness a medium-strength aurora recently in Iceland (KP ~3). We saw the classic rippling arc of green light, which at times seemed to consist of smaller flickering vertical ...
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$H_2O$ dissociation by ionization in a discharge tube

As a casual amateur scientist, I wonder if it is efficient to electrolyse water in a discharge tube. I imagine that there would be 4 electrodes arranged perpendicularly. the first set of electrodes ...
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Superman threw a net with a lot of nukes into the Sun. What happens now? [closed]

The iconic scene in "Superman IV: The quest for peace" shows the eponymous character throwing a net filled with nuclear missles into the Sun. If that were to happen in real life, what would happen as ...
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1answer
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Why is a spatial grid necessary in plasma simulations?

I am new to the topic and I am reading Plasma Physics via Computer Simulations by Birdsall and Langdon. The authors claim that working with a spatial grid is more efficient opposed to considering the $...
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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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Can a Tokamak-Based Mainframe feed Plasma to larger pipe-structure in order to create plasma-based propulsion engines?

Can a Tokamak-Based Mainframe feed Plasma to larger pipe-like structures in order to create plasma-based propulsion engines? It is a rather naive question.
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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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1answer
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In what cases should plasmas be considered compressible?

I was listening to a lecture where it was mentioned incompressibility was assumed during derivation of an electrostatic instability, but incompressibility was not assumed for an electromagnetic ...
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How to derive the induction equation for Spatial varying conductivity?

How to derive the induction equation from Maxwell equations (without displacement current) and Ohm’s law for Spatial varying conductivity?
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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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Ambipolar diffusion and sheaths in a bounded plasma

I am currently working through an introductory text book on plasma physics, and I have encountered two topics that I separately understand but seem to be at odds with one another. In a quasi neutral ...
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118 views

Splitting $CO_2$ as a plasma to remove it from the atmosphere

I am wondering if CO2 can be removed from the atmosphere by heating it up using the same lasers they use to make plasma when researching nuclear fusion, and then fire the plasma of oxygen and carbon ...
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Electric Field within and outside a plasma ball

According to the electric field strength's equation, electric field strength is inversely proportional to square of distance. Thus, electric field strength gets weaker as it is further away from the ...
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Gravitational and Electric Forces in the Movements of Planets [duplicate]

Now that we know about the electric nature of the cosmos, the question arises: "How much are planets affected by electric forces while moving through the universe?" We have been taught that the ...
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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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1answer
52 views

Two questions about Langmuir probe current-voltage characteristics

When the surface of Langmuir probe is a plane, the I-V curve has a shape like that illustrated in this figure: One can clearly note the existance of two regions of sauration, in which the current has ...
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why is clear electron saturation not obtained in a Langmuir probe experiment?

I recently conducted an experiment to study the I-V characteristics of a Debye sheath, but I can't obtain electron saturation. Why does it happen?
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How does the Earth's magnetic field protect it from the solar wind?

Several sources (see linked questions at the end) say that earth's magnetic field shields us from the solar wind. The general consensus is that without earth's magnetic field, the atmosphere would be ...
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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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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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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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282 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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255 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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Multiple Ion Species MHD

If I have a fully ionized plasma consisting of electrons and a mixture of different positive ion species of varying masses and charges...how can I use the MHD model to describe the plasma fluid motion,...
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886 views

Plasma recombination rate

Let's say I ionize a gas and create a plasma. I know this doesn't last very long because they recombine. But I don't understand why. Why do electrons give up their energy in the form of light and ...
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1answer
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Why does the ion and electron currents saturate in Langmuir probes?

From the I-V characteristics of the Langmuir probes used in Plasma diagnostics, we can calculate the plasma density, temperature, etc from the ion and electron saturation currents. But why does the ...
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Plasma Maintenance

What are energy efficient ways that can be used to keep a plasma in its fully ionized mode while minimizing losses due to recombination? Let’s say I have 1 mole of some material, and I need 15eV to ...
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Sampling Maxwell-Jüttner distribution for non-unity mass and speed of light

I am trying to sample Maxwell-Jüttner distribution using the Sobol method as described in Zenitani Loading relativistic Maxwell distributions in particle simulations (2015). Equation (2) in the paper ...
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Momentum mismatch on surface plasmon

I read Naturevolume 424, pages824–830 (2003). There is following sentence. "This increase in momentum is associated with the binding of the SP to the surface, and the resulting momentum mismatch ...
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Laser Solid Interaction

Can a continuous output laser fully ionize a surface to produce a plasma? I know of femtosecond laser pulses that do cause Coulomb Explosions, but what about in the case of continuous wave (CW) laser ...
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How to fully ionize plasma

How would I fully ionize plasma in a vacuum chamber? How would I know that it is fully ionized? Could I even come close? How could I measure how would I know how ionized the plasma is.
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Plasma Condensation

How can a plasma with ion temperature in the order of ~10^5 K be cooled to form a solid? Is there such thing as “plasma deposition,” where you could deposit arelatively hot dense plasma on a colder ...