What is plasmas: Definition and 23 Discussions

Plasma (from Ancient Greek πλάσμα (plásma) 'moldable substance') is one of four fundamental states of matter, characterized by the presence of a significant portion of charged particles in any combination of ions or electrons. It is the most abundant form of ordinary matter in the universe, being mostly associated with stars, including the Sun.
Extending to the rarefied intracluster medium and possibly to intergalactic regions, plasma can be artificially generated by heating a neutral gas or subjecting it to a strong electromagnetic field.The presence of 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 devices and technologies, such as plasma televisions or plasma etching.Depending on temperature and density, a certain number 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 a substance 'plasma' depends on the specific phenomenon being considered.

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  1. ZX.Liang

    I Some reasoning about Alfvén’s frozen-in flux theorem

    Alfvén’s theorem is very famous in plasma physics. It is also often used in astrophysics. The link in Wiki: https://en.wikipedia.org/wiki/Alfv%C3%A9n%27s_theorem However, after a series of continuous reasoning, it seems that this theorem has problem. What errors can be hidden in the reasoning...
  2. zaki belh

    A Question about kinetic theory and hydrodynamics (in plasmas)

    It is usual, in plasma physics, to combine the kinetic description for electron fluid and the hydrodynamic description for ion fluid, when studying the plasma properties or the dynamics of the electrostatic waves. I am wondering what are the physical meaning and limits of such an approach. Thanks.
  3. P

    A Notes on Cosmic rays - wave interactions in plasmas

    Dear community, I am Pedro de la Torre, now doing my PhD on Cosmic ray propagation. Now, I have started to study reacceleration due to interactions of CR with plasma waves. My problem is that I do not find neither a good book or any kind of review with a detailed demonstration on the...
  4. T

    New approach to stabilize fusion plasmas

    https://phys.org/news/2019-01-scientists-stabilizes-fusion-plasmas.html By applying more RF power to the unstable 'bubbles' that form in the plasmas.
  5. S

    How do microwave plasmas work?

    I'm new to PF, I have an engineering background, but am trying to understand how microwave plasmas are generated. I'm trying to work out if a tuned microwave waveguide can create a plasma in a specific point in the waveguide say over 30 seconds as the microwave energy heats up the waveguide thus...
  6. 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...
  7. T

    Highly collisional yet low resistivity plasmas

    In approximations for the applicability of ideal MHD to plasmas, it states that plasmas are considered highly collisional to permit the assumption that the plasma (i.e. electrons) follow a Maxwellian velocity distribution. Although is not resistivity based on collisions in the plasma? If there...
  8. T

    Does Centrifugal Force Cause Curvature Drift in Plasmas?

    Curvature drift in plasmas arise due to the centrifugal force that a particle sees when considering its guiding centre. Thus if one is following from the frame of the guiding centre, this drift will be observed. But for a stationary observer (let's say an experimentalist watching the plasma in a...
  9. 1

    Instruments to measure plasmas besides Langmuir probes?

    If a plasma is created at one end of a solenoid and heads down towards a target with a density and temperature too high for Langmuir probes, what other instruments can measure the density with a strong signal that is easy to interpret?
  10. I

    Can all elements be turned into plasma?

    I'm not sure where to post this so forgive me if the is the wrong place. Can any element be a plasma or only certain ones? Could you make iron plasma?
  11. F

    Looking for research which encompasses both plasmas and fission.

    So far I've only found some leads into the use of magnetohydrodynamics theory in designing liquid metal cooled reactors. Anyone know of any other topics?
  12. Q

    Book on Diamagnetic drifts in Plasmas within Magnetic Fields

    Hi guys! So I just need help in one tiny thing. Does anyone know a good book that can thoroughly explain physically and mathematically diamagnetism in plasmas within magnetic fields? I would really appreciate the help guys! Also, I am very much familiar with vector calculus (also tensor calculus...
  13. Astronuc

    Astrophysics Physics Of Space Plasmas: An Introduction, 2nd Ed, by George Parks

    Author: George Parks Title: Physics Of Space Plasmas: An Introduction Amazon Link: https://www.amazon.com/dp/0813341299/?tag=pfamazon01-20 Prerequisities: Introductory physics, modern physics, calculus through PDEs, E&M, introductory astrophysics/astronomy (basically three years of a...
  14. E

    Exploring Dusty Plasmas: What Are They?

    what is really dust-laden plasmas? :)
  15. T

    Understanding Coulomb Force in Plasmas

    This may be a pretty dumb question. How is it possible for ions and electrons to coexist in plasma state. Shouldn't be there Coulomb force between them so that they would be bound together and become atoms?
  16. D

    Trying to apply electric current to plasmas in motion.

    How do you represent a certain mass of plasma (ions and free electrons) traveling inside a containment from point A to point B as "I", electrical current? Trying to make a connection, Doug Ettinger
  17. D

    The affect of different plasmas on each other

    What occurs if a higher velocity, denser plasma plowed through a less dense plasma traveling at a lower, but parallel velocity ? Do mutual magnetic or electric inductances between the two plasmas occur ? Regards, Doug Ettinger
  18. H

    Cylindrically symmetric plasmas and models for.

    Hi, I have currently been thinking about laser-plasma interaction and I have a simple model in mind. I am going to look for a cylindrically symmetric solution of a cylindrically symmetric laser beam (of radius R) hits a initially charge neutral plasma creating an electron beam in the plasma...
  19. N

    Levitation using microwave-induced plasmas

    Hi all, I came across this interesting paper the other night: http://www.odu.edu/~spopovic/index_files/pub/LevitationPaper.pdf An experiment was conducted involving the levitation of a Syrofoam object above a plasma created by a microwave horn. The following explanation given for the...
  20. T

    Electromagnetism and Plasmas

    A plasma is described by the dielectric function \epsilon (\omega) = \epsilon_0 (1-\frac{\omega_p^2}{\omega^2}) where \omega_p is a constant. Any attempt to establish a voltage V(t) = V cos \omega t across the plasma generates a region of vacuum called the "sheath" on either side...
  21. mheslep

    Confinement of Thermalized plasmas: Why not E instead B?

    I'm pondering the density limits realizable in thermalized plasmas (as in Tokamaks) and it seems that confinement by a rotating electric field (something like a Paul trap) would theoretically allow much higher densities than the current magnetic field techniques. No doubt I'm missing something...
  22. P

    Exploring Magnetic Energy with Plasmas: A 11th Grader's Challenge

    I just started physics, I am in 11th grade and we needed to do a project in some class and I want to do this, but I really need help. I asked my teacher about doing something on magnetic energy (I would have no clue where to begin though…) and she brought up plasmas and doing something on those...
  23. E

    Solving Plasmas and Magnetics Questions with John

    Questions garanteed to have you doing right handed impressions of rap artists by the end! :smile: :tongue: Now I am much happier with electronics, I decided to start reading about magnetics. However, I'd appreciate any help you could provide with a few things I'm thinking about. First of...