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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Why is electron temperature in plasma higher than ion temperature?

Wikipedia states that The electron temperature of a plasma can be several orders of magnitude higher than the temperature of the neutral species or of the ions. This is a result of two facts. ...
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104 views

Is an electric field a transverse wave not in a vacuum?

According to "Introduction to Plasma Physics and Controlled Fusion 3rd Edition", in discussing electromagnetic waves in a plasma, $\vec{E}$ is said to be a transverse wave. Is $\vec{E}$ a transverse ...
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108 views

What accelerates the solar wind?

The question is in the title. A bit of background info: the escape velocity at the photosphere of the Sun is ~ 620 km/s, but the mean speed of the solar plasma there (inferred from the temperature) ...
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114 views

Drift kinetic equation orderings

I'm trying to derive the first order drift kinetic equation given in the book Collisional Transport in Magnetized Plasmas by P. Helander and D. T. Sigmar, section 6.5. I understand that the ...
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In a plasma, can the ion temperature become larger than the electron temperature?

Let's assume a hydrogen gas, initially at low temperature The density is low enough so that heating of this gas by inverse bremsstrahlung can be neglected. Now if a high-intensity radiation source ...
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Why all the orifices, protuberances, hinged/bolted panels, etc. on a stellarator?

My question was inspired by this one - in particular the image it has (also shown here): Why does the external casing of the Stellarator (in particular, the Wendelstein 7-X shown in the above image) ...
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25 views

Incomplete Fermi-Integral to link solid and plasma: Did this autor make a mistake?

At some point int his paper[1] the author defines a function: $$f(T)=\int_\mu^\infty F(\epsilon,T)d\epsilon$$ where $$F(\epsilon)=\frac{g(\epsilon)}{1+e^{(\epsilon-\mu)/kT}} d\epsilon$$ and $$g(\...
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Does light actually travel in a straight line?

Sir Issac Newton said that light travels only in a straight line. But in a burning candle, as flame is in upward direction the light from it does not travels in a straight line; it spreads. What is ...
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71 views

Why is the Paschen Law linear at large pd values?

The Paschen Law becomes linear at larger $p\times d$ values but what's the origin of this linearity? Does it come from the homogeneous electrical field? I understand that the origin is partially due ...
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21 views

Localized electrostatic-acoustic disturbance

From this youtube comment it describes a 'localized electrostatic-acoustic disturbance' as a 'very rapid, sudden static charging of the atmosphere'. I've done some lite searching but haven't found ...
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3k views

What is the physics behind the plasma frequency?

I can't seem to find a satisfactory, intuitive explanation for the way electromagnetic waves behave when they encounter a cold plasma (that is, one where $\omega^2 = \omega_p^2 + c^2 k^2$). My ...
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800 views

What is the critical electron density in a plasma?

In the article Ion Acceleration and D-D Nuclear Fusion in Laser-Generated Plasma from Advanced Deuterated Polyethylene by Lorenzo Torrisi, the author mentions a critical electron density on page 17057....
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309 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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173 views

What is the physical basis for Pedersen and Hall currents in an atmosphere?

There are three components of a conductivity tensor in atmospheric electrodynamics: the parallel conductivity along the direction of the magnetic field, the Pedersen conductivity (in the direction of ...
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393 views

What is the viscosity of Sun surface?

It should be possible to compute value from hydrodynamics of Solar prominence. What is the current estimate of Solar surface viscosity?
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323 views

Can metals be ionized by radiation?

In gaseous state a laser can ionize metal atoms and create a plasma. But what about the solid state? Is a high intensity laser able to ionize a solid metal?
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112 views

How much heat is needed for an atom to be ionized? [duplicate]

We all know that heat or high voltage makes atoms into an excited state, stripping off the electrons off of their nucleus. But how much heat do you exactly need to create plasma, or have the majority ...
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153 views

Does photon electromagnetic field “shake” charged particles and atoms?

Lets theoreticaly imagine completly stationary particle,like electron for example.Can photon,or photons shake it,or oscillate its position? By that I dont necesarily mean the center position must ...
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31 views

How are electrons “captured” in magnetron sputtering deposition?

To clarify,I am thinking about certain PVD coating technology called magnetron sputtering, vacuum chamber is filled with noble gas and glow discharge plasma sputters target whose atoms deposit as thin ...
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1answer
78 views

Lift using electricity to create pressure difference

Is it possible to step up the notch and create the lift effect used in airplanes and helicopters without moving parts? By "moving parts" I mean helicopter blades moving at high speeds to create ...
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40 views

Momentum when slow ion collides with fast electron?

Imagine high voltage alternating frequency glow discharge plasma between two plate electrodes with gas atoms inside. There will be free electrons and positive ions.During first half of the sinewave ...
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Interpretation of constant length scale in ionospheric propagation

I'm studying electromagnetic propagation in the ionosphere. The starting point is Maxwell's Equations in an inhomogeneous medium, plus the assumption that these inhomogeneities occur at length scales ...
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103 views

On what factors does the electron density in a plasma depend?

Pretty much what the title says. Any link to papers which give an explicit dependance of electron density in a plasma is welcome.
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153 views

Does a homemade evacuated tube produce X rays?

Recently, I've bought a tiny USB powered spark gap bipolar Tesla coil (rated at 15 mA and (35-50)kV). I am a pretty interested in spectroscopy, so I played around with the tesla coil and a couple of ...
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325 views

Why do plasma filaments of plasma globes move outwards towards the glass?

In plasma bowls, the plasma filaments made of ionized inert gases extend from the central 'mini Tesla coil', all the way to the glass outer sphere. What makes them want to go to the glass? Why don't ...
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1answer
49 views

Why are there more trapped protons during solar minima?

Reading about trapped protons and eletrons in van Allen belts, I get the understanding that the number of trapped electrons increase during a solar maximum (which I find logical because we have more ...
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118 views

What's the loss of information in taking the moments of the Vlasov equation for the Particle-In-Cell method

I know that when deriving the hydrodynamic equations from Boltzmann's equation we take the first three moments along momentum space to get the conservations laws. Taking infinitely many moments would ...
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1answer
61 views

Linearized Euler-Poisson equation

Normalized Euler-Poisson system have the form $$n_t+(nu)_x=0$$ $$u_t+uu_x=\phi_x$$ $$\epsilon^2\phi_xx=n-e^\phi$$ where $u $: ion velocity, $n$: the ion density and $\phi$: electrical potential, The ...
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What are these alternating bright and dark rings in fluorescent lamp?

I'm quite surprised by these regularly spaced rings of alternating brightness in a fluorescent tube. These are also moving along the tube and only appear when the voltage is low. What are these and ...
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1answer
145 views

Can't prove that Fast Magnetosonic Wave's proper speed is given by the following formula

So, suppose a magnetosonic disturbance, it is proven that (You can also see it in Richard Fitzpatrick's Plasma Physics online text), that the Fast Magnetosonic Wave is equal to \begin{equation} \dfrac{...
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2answers
406 views

Temperature and energy of ions and electrons at Ionization

For Xenon atom, as the ionization energy is 12.13 eV , does it mean that if 12.13 V is applied, the Xenon atom can be ionized. Also, Could you share, how to find the temperature and energy ...
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43 views

Image of spatial distribution of particles in a plasma?

I am looking into the Debye length and to get an intuitive understanding of it I thought I would find an image showing a simulation of the (spatial) distribution of particles in a plasma i.e. a zoomed ...
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2answers
142 views

Plasma phase transtition from a Landau symmetry-breaking perspective

My question is a follow-up to Is there a phase transition between a gas and plasma?, with an emphasis on the symmetry-breaking aspect. These questions only refer to electromagnetic plasmas - not quark-...
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1k views

When does Debye shielding occur?

I know that the phenomenon of Debye shielding is present when you place an additional charge $Q$ into an otherwise homogeneous, neutral medium. This case is however very special and I was wondering - ...
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1answer
192 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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2answers
1k views

Elements and their plasma state

I'm looking for a list of nearly all elements and the temperatures they can reach when in a state of plasma. It is for a project I am working on. However, there isn't a list on google. Preferably one ...
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32 views

Is it possible to use fluid model for behaviour of non thermal/cold plasma

I need to study the impact of magnetic field on dielectric barrier discharge plasma in plasma actuator configuration. But i have read that the velocity distribution is non maxwellian so i am a little ...
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1answer
49 views

Smallest relative velocity driving a two-stream instability

The physical picture is a two-stream system of cold electrons and ions (i.e. $T_i=T_e=0$) with realtive velocities $V_i$ and $V_e$. The dispersion relation obtained is $$D(\omega)=1-\frac{\omega_{pi}^...
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324 views

What does a retarding field energy analyzer measure?

According to [1], p.58, the current collected by a retarding field analyzer is: $$I= qA \int^\infty_{v_{min}} vf(v)dv $$ where $q$ is the electron charge magnitude (here singly charged ions are ...
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593 views

What is the difference between bulk speed and thermal speed in solar wind plasma?

in solar wind plasma different species has different thermal speed but all having same bulk speed. why it is so? and in solar wind is the thermal speed is just the standard deviation around the bulk ...
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58 views

Do coronal mass ejections dissipate or decay over time?

What is the life cycle of a CME after it is ejected? All accounts I've seen focus on impacts at Earth, but don't suggest how it evolves over time as it progresses away from the Sun. Does it expand, ...
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220 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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1answer
163 views

Lightning plasma density

According to [1], the plasma produced by lightning has a temperature ~ 28,000 K, and an electron density ~ $10^{24} / \rm m^3$. What is the density of the plasma in $\rm kg / m^3$? [1] https://www....
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478 views

intuitive explanation of $E \times B$ drift with constant and perpendicular $E$ and $B$

As stated in this question, the force on a charged particle in electric field $E$ and magnetic field $B$ is given by: \begin{equation} m \dot{v} = q ( E + v \times B) \end{equation} Then, the $E \...
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How does one calculate the evolution of a species in a low energy plasma over time?

I am currently working on a global modeling program for low temperature plasma and I have hit a wall. My goal is to graph the evolution of a species as a function of time using an approximation of the ...
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1answer
394 views

breakdown voltage in vacuum

I was trying to use the paschen's law to calculate the breakdown voltage for our vacuum chamber. Our pressure is 10^-8 torr, and distance was 3mm. However, I cannot do it because Paschen only worked ...
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497 views

How to get the moments of the Boltzmann equation?

I'm currently reading through a hydrodynamics lecture course and I'm confused at some of the key integrals that are derived. These integrals aid in deriving the moments of the Boltzmann equation. ...
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275 views

Can plasma under ANY circumstances get attracted to a magnet?

Can plasma under ANY circumstances get attracted to a magnet? y/n If so, then under what circumstances?
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Is there any Electric Current on (Solar) Coronal Loops?

I'm studying Plasma Astrophysics and now I have came across the following problem, which I have been trying to solve on my own, and came to a "non-logical" conclusion? Here is the Problem: Let the ...
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229 views

Is it possible to create a photon with energy lower than the plasma frequency inside a plasma?

Suppose we have a plasma with corresponding plasma frequency $\omega_{\text{pl}}$. Next, assume that there is some scattering inside the plasma, due to which photons can be created. Is it possible to ...