What is Plasma: Definition and 675 Discussions

Plasma (from Ancient Greek πλάσμα 'moldable substance') is one of the four fundamental states of matter, first systematically studied by Irving Langmuir in the 1920s. It consists of a gas of ions – atoms or molecules which have one or more orbital electrons stripped (or, rarely, an extra electron attached), and free electrons.
Plasma can be artificially generated by heating a neutral gas or subjecting it to a strong electromagnetic field. The presence of free charged particles makes plasma electrically conductive, with the dynamics of individual particles and macroscopic plasma motion governed by collective electromagnetic fields and very sensitive to externally applied fields. The response of plasma to electromagnetic fields is used in many modern technological devices, such as plasma televisions or plasma etching.Depending on temperature and density, a certain amount of neutral particles may also be present, in which case plasma is called partially ionized. Neon signs and lightning are examples of partially ionized plasmas.
Unlike the phase transitions between the other three states of matter, the transition to plasma is not well defined and is a matter of interpretation and context: Whether a given degree of ionization suffices to call the substance "plasma" depends on a specific phenomenon being considered. In other words, plasma is a matter which cannot be correctly described without the presence of charged particles taken into account.
Excluding dark matter and the even more elusive dark energy, plasma is the most abundant form of ordinary matter in the universe. Plasma is mostly associated with stars, including our Sun,
and extending to the rarefied intracluster medium and possibly the intergalactic regions.

View More On Wikipedia.org
Recent contents Top users
  1. QuarkDecay

    MHD Equilibrium: Prove P+B2/8π

    Homework Statement Prove that in an MHD equilibrium state in a pinch with flux and Bθ(r) and Bz(r), the equation for pressure is; d/dr(P + B2/8π) + Bθ2/4πr - ρ( u2θ/r)= 0 B is the total Magnetic field, uθ(r) the velocity of plasma, ρ= density, and solving in a (r,θ,z) system Homework...
  2. QuarkDecay

    I Gas Density & Plasma: Is Higher Better?

    In general, when we say that in a fermionic gas the higher its density, the better we can consider it to be a plasma instead of gas?
  3. QuarkDecay

    A Velocity Drifts of proton-muon gas

    When do we use the equations of curvature drift ( ΔΒ⊥Β) V∇B= ±1/2u⊥rL (B x ∇B)/B2 and the general VF= c/q (F x B)/B2? For particles like muons and protons, do they need different equations to calculate a gas' drift velocity, when the gas is made of protons or muons instead of electrons? Am I...
  4. QuarkDecay

    When is the Boltzmann equation applicable in a Fermi plasma?

    When do we use the Boltzmann equation for density in a Fermi plasma? n in [cm-3] and when do we use the ρ=m/V, ρ in [Kg/m3 ] (this is not an example, I just added the equations to make my question more understandable) Is the ideal gas only when we have electron and ions? Is the Boltzmann...
  5. QuarkDecay

    Electron Plasma to Muon/Proton

    Homework Statement Cylinder electron gas with density of ne= 1010 and radius or r=1cm is inside magnetic field of B=104 Gauss. If we change the electron gas with (i) muon gas (ii) proton gas does the Drift Velocity change? Homework Equations [/B] Boltzmann equation of density...
  6. Dan Jenson

    E Field at a Glow Discharge Tube Cathode

    I am trying to understand the "strong" negative E field in the Aston Dark Space in the thin region close to the cathode or else even the cathode surface. See the diagram at: http://www.glow-discharge.com/?Physical_background:Glow_Discharges My question regards the "Electrical Field E" graph...
  7. P

    Probability per atom and per second for stimulated emission to occur

    Homework Statement We are investigating hydrogen in a plasma with the temperature 4500 ºC. Calculate the probability per atom and second for stimulated emission from 2p to 1s if the lifetime of 2p is 1.6 ns Homework Equations ##A=\frac{1}{\Sigma \tau}## $$A_{2,1} = \frac{8*\pi *h *...
  8. R

    How do plasma particles interact with a magnetic field?

    How does plasma particles (ions, electrons, neutral particles as a whole) interact with an applied steady-state magnetic field? If you have plasma at atmospheric pressure ejected from a plasma torch in the z-axis direction (upwards/north), how will two permanent magnets, axially aligned N-S to...
  9. J

    How does the corona develope into stream and disapear finall

    How does the corona develope into stream and disapear finall
  10. Jan Berkhout

    How is current induced in the plasma in a tokamak?

    For a Year 12 Assignment I have to do a seminar on how magnetic fields are involved with a certain topic. I chose nuclear fusion energy production and specifically the tokamak. I understand that a toroidal magnetic field is created when a current is sent through a solenoid wrapped in a torus...
  11. T

    I Calculating the curvature drift in a plasma

    How do i get this equation, $$\frac{db}{dl}=(\hat{B}.∇)\hat{b}$$ This equation is a vector whose direction is towards the centre of the circle which most closely approximates the magnetic field-line at a given point, and whose magnitude is the inverse of the radius of this circle. However I...
  12. Pouya Pourkarim

    How Can PF Enhance Learning in Plasma Physics and Cosmology?

    I study engineering physics and I’m interested in plasma physics and cosmology
  13. W

    Phase relation between the electric & magnetic fields in a plasma

    Homework Statement So I have got the question below. I am asked to find the phase difference between the electric field and magnetic field of electromagnetic waves traveling in a plasma, using the electrical conductivity expression. Now I have found the frequency of the waves and I know that...
  14. M

    After a lightning bolt, what happens to the plasma?

    When a lightning bolt strikes the earth, the air molecules are turned into plasma which causes the "light" that we see. What happens to the plasma air molecules after a lightning bolt? Do the positive/negative charged molecules find free electrons in the air and resume to be neutrally charged...
  15. D

    Basic Question -- Powering a small plasma ball with a battery

    HI, I have embarked on a small project basically it is for my daughters dance routine prop. I was wondering if I could power a small plasma ball with a battery. The plasma ball power supply specs are: Output: DC 12V 350mA MAX 4.2W It has to be mobile it will sit on a small table which has to be...
  16. Kiwimaster76

    I How does plasma act outside of a containment field?

    If you were to have some way to remove plasma out of a tokamak or stellarator, how would it act? I realize there's basically no way to actually remove plasma from those machines, but I'm curious how plasma would act in the actual atmosphere. Would it act like a plasma cutter? Would it stay...
  17. J

    Enthelpy of fusion/vaporization/sublimation to a plasma?

    I may be grossly generalizing the principle, but is there a way to calculate the energy needed to transform a solid/liquid/gas into plasma? Information is easily found on enthalpy of fusion/vaporization/sublimation, but I couldn't find anything regarding transforming to the 4th state of matter...
  18. Ryan Doucette

    Nuclear Fusion: Electron Thermal Transport Terminology

    I am an undergrad physics major in my final semester currently taking Intro to Thermodynamics. As a final project, each student must choose a topic related to thermodynamics that is more advanced than what is covered in the curriculum and write a paper and present our findings to the class on...
  19. D

    MicroVoltage fuse (Now "Sensing the Flame-Front of a Plasma")

    I have not had any luck finding a fuse that will burn out fast at voltages below a volt. Is there no such thing? Thanks!
  20. J

    I Thermal field theory of an isolated electroweak plasma

    The theory of electroweak temperature says that when you have a plasma of particles at energy above the electroweak phase transition (100 GeV). The Higgs field would turn from nonzero vev to zero and the electroweak forces would unite and the electroweak bosons would become massless. What...
  21. H

    Plasma ball electric shock mystery

    Plasma ball has a high voltage. Why don't we get an electric shock when we touch it?
  22. spareine

    Plasma ball, energy levels of neon and xenon

    I was wondering about the filament colors in a plasma ball that I have got. The main part of each filament is blue, but its end part is pink. Possibly the gas is 95% neon and 5% xenon, the pink part is light emitted by neon, and blue part light emitted by xenon. Using a hand spectroscope I...
  23. A

    Propagation length of the surface plasma wave (SPW)

    Hello, Many Researchers talked about the following parameters: 1. Propagation length of the surface plasma wave(spw). 2. penetration depth of surface plasma wave(spw). 3. concentration of the (spw). 4. the equation of the interface in vacuum - plasma interface. I feel confused regarding such...
  24. S

    I Does plasma react to eletromotive force

    Does plasma react to eletromotive force
  25. J

    Plasma: Separate Electrons & Positive Ions

    If plasma is just ionized gas isn't it basically just a sea of mobile electrons but in gas, if not then how can a bunch of electrons and positive ions stay separate and the gas ionized for long.
  26. R

    Plasma Generation using Dielectric Barrier Discharge

    I am having trouble in making a power source for the DBD. I can't seem to find any calculations to get the required voltage and frequency of AC to generate plasma. I want to know the circuit/method/equipment needed to generate that voltage from a normal 220 V/50 Hz AC socket in my lab.I am doing...
  27. B

    I Plasma Oscillation Explanation

    A plasma is quasinetural with the negative charges (electrons) being much lighter than positive ions. When an electron is perturbed, the attractive force acts to restore it with a particular frequency. This was the explanation given to me for plasma oscillations. However, the equation presented...
  28. Mzzed

    I Interpretation of spatially dependent convective derivative

    <Moderator's note: Moved from the homework forum.> Homework Statement The following equation is one of a few equations that describe a plasma model. The left hand side is the part I am having trouble with in that I can't seem to visualise what (V dot delV) actually does. My physics teacher has...
  29. B

    I Hydrogen plasma compression with liquid Mercury piston

    I'm working on a thought experiment. I want to know how much of the kinetic energy from a liquid mercury piston will be converted into work done on the hydrogen plasma in the form of compression, and how much work will be done on the piston in the form of compression. Note: assume piston walls...
  30. chandrahas

    Do force drifts occur in highly collisional plasmas

    I've read on wikipedia that the force drifts of the guiding centers off particles in a magnetic field also occurs in cold plasma. But does it occur in a cold plasma (Partially Ionized ) in which the mean free time is less than the gyro frequency time? I thought that the drift were present...
  31. C

    Does electron gas in metals experience viscosity?

    Does electron gas in metals experience viscosity? Also, does highly charged plasma experience viscosity?
  32. chandrahas

    B Containing a plasma with a oscillating cusp?

    I've recently learned that conductors can achieve stability when placed in an alternating electric field. This is because of Lenz's law. So I was wondering if we could levitate a conductor and stabilize it, can we do the same thing with a plasma? If we can create a magnetic cusp, but oscillate...
  33. jedishrfu

    Can scientists finally contain lightning in a bottle with a stable plasma ring?

    https://futurism.com/stable-plasma-ring-created-open-air-first-time-ever/
  34. TJGilb

    Graduate Programs Advice (Particularly for Plasma Physics)

    Greetings everybody, Right now I'm applying to graduate physics programs, but since it's an expensive process I'm trying to be at least a little selective in my approach. Since my research interests are in plasma physics, I've limited myself to schools with a program in such. So far I've...
  35. A

    Plasma wire -- turning an antenna on and off very quickly

    Someone asked if it was possible to conduct electricity through a wire with a plasma. I ran across a article about a inventor who wanted to turn a antenna on and off very quickly. He said it was possible to do this by using a florescent light bulb as a element in the antenna. When a...
  36. S

    I Can anyone help with this satellite question?

    I must find parameters for equation [1] in this link http://onlinelibrary.wiley.com/doi/10.1002/jgra.50543/pdf for satelite in height from 100km until 300km. Have to use IRI and IGRF. Any help with answer?
  37. S

    A Taylor expansion of dispersion relation - plasma physics

    Hello, I may working through attached paper and really need help with deriving equation in appendix - A4 to give A10. http://iopscience.iop.org/article/10.1088/0004-637X/744/2/182/pdf Any help would be greatly appreciated. thanks, Sinéad
  38. S

    A Plasma physics - relativistic derivation

    Hello, I am trying to work through attached paper, deriving from equation 2.2 to 2.4. I am not familiar with the notation. If I try and get the integral of inside the <> brackets, I end up with a different eqn 2.4. I need some maths help here :) Any help would be greatly appreciated...
  39. K

    B Does the plasma at the center of a star act like a solid?

    I was passing time by Googling the properties of the sun (temperature, mass, etc) and got to wondering what lies at the center of stars. I found out its plasma under roughly 340 billion atmospheres of pressure. I realize Boyles law may not be strictly meant for plasmas, but using it I...
  40. E

    Collisional sheaths in atmospheric pressure plasma

    Hello, I'm studying dielectric barrier discharges (DBD) at atmospheric pressure. I'd like to have some references on highly collisional sheaths in radio-frequency discharges. I know the treatment becomes very complicated and one usually uses kinetic simulations, but nonetheless I'd like to see...
  41. Scott_10438

    Equation for plasma wave/light speed travel?

    Hi guys I'm finishing up some promo art for my original comic book. You're seein it here first. But its missing something- an appropriate equation. I would like to integrate a math equation into the art. I am attempting to depict FTL travel, using qualities similar to an LWFA, the plasma being...
  42. M

    I Questions about plasma physics

    i study the electrostatic waves at plasma (as a beginner) and i come to some questions and hope to find a help 1) how could we ignore magnetic field (taking B =0) although we have oscillating charges (what particularly electrostatic wave means ) 2) at studying ion acoustic they always...
  43. EL_bob

    Magnetic assisted rocket engine

    Hello everybody! I have been thinking about something for a while now. I would like to make a magnetic nozzle for a rocket engine. Basically, I would like to ionize the hot and high pressure gaz in the combustion chamber and then use a strong magnetic field to adjust the nozzle throat...
  44. F

    Dispersion Relations in Cold Plasma waves

    Homework Statement Im stuck on a old exam in plasma physics. It is about how to determine dispersion relations for high frequency waves in cold plasma's. I'm not sure how they do in the solution manual. Homework Equations B = B_0z^ E = E_0exp(i(kx-wt))z^ The Attempt at a Solution The...
  45. Jayant Dabas

    Can we create femtosecond laser instead of buying it

    Is there a possible way to redesign femtosecond lasers to reduce cost?
  46. J

    I Interpreting Copper & Argon Emission Spectral Lines with Plasma Spectroscopy

    Hi, I recently started working on MPD Thrusters. During a recent experiment, spectral images (uncalibrated) were obtained. The thruster is made of copper and the propellant is argon. These two elements will be the source of emission spectral lines. I need help to interpret them. I have...
  47. 2

    I Plasma self-focusing index of refraction < 1?

    Hi. After reading about self-focusing in plasmas I came across the relative index of refraction that a light wave experiences during the interaction with plasma. Namely n = \sqrt{1-\frac{{\omega_p}^2}{{\omega}^2}} where \omega_p is the plasma frequency and \omega is the light (for example laser)...
  48. A

    Plasma arc with multiple electrodes

    is it possible to create a plasma arc across multiple electrodes? like: cathode___ anode____________________cathode then back to anode from source? is this possible? and if yes does it need electrolyte at the anode in the middle and how to apply it?
  49. A

    I Time of cooling to equilibrium in space plasma gas

    Hi all, If I have a hot object in space (not a star but say an oven or just a hot gas as would be on Earth < 10,000 degrees Kelvin) glowing at a temperature T and I want to know long it takes to come to equilibrium with the vacuum of space around it, how can I calculate such a time? I could...
  50. A

    How to calculate the voltage needed to create a plasma

    i've been reading on plasma physics and i have a couple of questions. how to calculate how much volts needed to create plasma with distance x from the electrodes of a certain gas with certain pressure? and to increase the distance do i have to increase voltage or once i have an arc or plasma in...
Back
Top