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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1answer
362 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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281 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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1answer
108 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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3answers
144 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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30 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
70 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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0answers
25 views

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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99 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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1answer
135 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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1answer
308 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
48 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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1answer
115 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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2k views

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
142 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
395 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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1answer
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
137 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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3answers
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
180 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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0answers
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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1answer
298 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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572 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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1answer
55 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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1answer
194 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
151 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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5answers
450 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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34 views

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
354 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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1answer
469 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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1answer
260 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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1answer
51 views

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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1answer
205 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 ...
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1answer
2k views

How many times does plasma do a full loop tokamak before fusion?

From this photo I assume the plasma is also moving in a loop through the reactor due to it being a charged particle. I have been trying to find a speed at which it does this but couldn't and neither ...
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1answer
119 views

Why does Dielectric Barrier Discharge (DBD) power scale with the driving frequency?

While reading this review on dielectric barrier discharges (DBDs), I came across an apparently widely-applicable formula for calculating the power of a DBD. The formula states that the DBD power is ...
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77 views

How powerful of an electric current would I need to fully ionize plasma under the specific circumstances below?

in a cylinder shaped vacuum chamber 4 inches in height and 5 in diameter at 1/100th atmosphere, with 3 cathodes at the face arranged in a equilateral triangle in exactly between the center and and the ...
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0answers
58 views

Can air plasma ions in a fusor fuse?

I know that hydrogen ions will fuse in a fusor but what about air ions? Can air plasma ions in a fusor fuse? https://en.wikipedia.org/wiki/Fusor, if so, under what cicumstances, and how would I ...
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1answer
250 views

How to calculate the bremsstrahlung limit in the fusion triple product diagram?

The fusion triple product is a commonly used figure of merit to quantify the progress in fusion research, it is the product of plasma density $n$, temperature $T$ and energy confinement time $\tau_E$....
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How ionized is the plasma in a Crookes tube

How ionized is the plasma in a Crookes tube, at $10^{−6}$ to $5 \times 10^{−8}$ atmosphere ($7 \times 10^{−4}$ – $4 \times 10^{−5}$ torr or 0.1–0.005 pascal). Under any of these circumstances is it ...
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1answer
60 views

For the purposes of intergalactic space travel, would IGM or other intergalatic particles be an issue?

Basically, I'm seeing that intergalactic medium can sometimes have a temperature in excess of 10^5 K. Would the high temperatures have an effect on intergalactic travel?
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1answer
135 views

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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2answers
189 views

Trying to understand Paul traps

Paul traps have been confusing me a lot recently. So sorry if there are too many questions I know that Paul traps confine ions with the help of rapidly switching quadruple electric fields, I've heard ...
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0answers
85 views

What's the energy density of longitudinal wave in plasma?

For longitudinal wave, the magnetic and displacement fields are zero, then according to the common formula (by which I mean (D$\cdot$E$^*$+B$\cdot$H$^*$)/2) for the energy density of electromagnetic ...
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3answers
473 views

Can electric fields penetrate a plasma in the presence of a magnetic field?

Generally, electric fields can't penetrate plasmas, and this is known as debye shielding. But when I was thinking about the E cross B drift, this hit me. The average motion of a particle along the ...
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1answer
48 views

Construction of a plasma model

I would like to start to build a plasma model. Though Beginning is posing a struggle. What is the simplest way to go about modelling a plasma? Are there any tricks to it?
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210 views

What causes instabilities in tokamaks?

As far as I know, almost all kinds of instabilities are suppressed in a tokamak. The only problem I see is that the poloidal field diminishes as we move further out from the plasma. This ...
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1answer
301 views

Is there such a thing as “cold plasma”?

Plasma is cool, but can it be cold? Materials have different temperatures for phase transitions (boiling, melting, ...). Do these also differ when it comes to plasma? If yes, is there such a thing as ...