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.

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  1. M

    What is plasma in aerospace?

    what is plasma in aerospace?? ive heard of graduate programs focusing on plasma. i thought this was physics, not aerospace engineering. can you please help me understand what this covers in a practical sense, what math is associated with this focus, and if it is practical
  2. M

    Magnetohydrodynamics - Plasma or Liquid more conductive?

    Sorry, I am not a physics major - I apologize in advance if this question is ignorant or if this was asked already. What would be the most effective as a Magnetohydrodynamics weapon? Assuming normal ionized air, would a liquid (liquid silver and salt water) or some type of plasma...
  3. R

    High Pressure Cryogenic Dusty Plasma

    i'm studying the coulomb structure of 0.3um acrylic particles in He plasma. At low pressure, around 30 Pa, the negatively charged dust particles can be suspended above the negative RF electrode. However, at around 100-150Pa, all particles have fallen onto the electrode itself, making it...
  4. R

    Exploring the Electromagnetic Effects of Helium Plasma on Earth & Jupiter

    Given the above quote reference Helium within our Heliosphere, I have a grouping of questions for the electromagnetic wise. If Earth and Jupiter were both placed within a dense Helium plasma region/field of our Heliosphere at the same time; and considering He plasma's high electrical...
  5. B

    Plasma Frequency and Work Function

    are there any dependencies in these things? In different metals
  6. T

    How many years until Ion Plasma thrusters are used on space ships?

    Thanks, just curious ever since I watched Prometheus.
  7. 1

    Can we experience plasma by rubbing hands together?

    Here's the story, me and my boyfriend share things we learned from attending seminars. He told me that a speaker in one of the seminars he attended last month told them that by rubbing our two hands together, we could experience the presence of 'plasma' - the fourth state of matter. Here's...
  8. P

    Question about osmotic pressure of blood plasma

    Homework Statement The osmotic pressure (π) of the blood plasma necessary to induce absorption of water from interstitium (outside) to the capillary bed under circumstances shown on the picture (attached) has to be a. Less than 20 mmHg b. Between -1 and 20 mmHg c. Equal to 21 mmHg d. Greater...
  9. K

    Noble gases converted to plasma?

    A partnership of companies known as Plasmerg and Intelligentry have been making some, in my opinion, crazy claims they refer to as a Plasmic Transition Process. Nevertheless my curiosity keeps me honed in on their progress reports. They claim they use a mixture of five noble gasses [ie...
  10. S

    Velocity of Electrons and Protons in Plasma Loops

    Is there an equation to find out the velocity of electrons and protons in a loop of plasma when a current is induced through it?Is the velocity just equal in magnitude and opposite in direction or is it opposite in direction and the velocity dependent on mass of the particles?(implying that an...
  11. I

    Will a Knotted Flux Tube in a Plasma Tend to Move?

    Suppose I have a plasma. Inside the plasma is a knotted flux tube in an electric field. Will it tend to move? Is this there a better forum for this question?
  12. L

    Magnetic Mirrors: Exploring Conservation & Torque in Plasma Physics

    I'm taking a short course in plasma physics, and we've covered quickly the magnetic mirror. So the idea is that an ion, say a proton, moves along a helical path along parallel B-field lines - say in z-direction. Then the lines converge towards the z-axis, forming a shape like a bottleneck, with...
  13. C

    Dielectric Barrier Discharge Plasma Discharge Circuit

    To anyone that can help me, Hello everyone. I am student from Mechanical Engineering and I am very new to electronic field. I currently doing my final year project which is developing the high voltage discharge circuit for the DBD plasma. The middle electronic elements is the representative...
  14. F

    Creating Air Plasma Conductor Stunner Beam: Is it Possible?

    i've been thinking about creating some sort of taser like weapon. As we know, taser range is limited by the length of the wire and the weight of the electrode. So it's only usefull over short distance. What intend to create is some sort of stunner beam. Here's how it'll work. the first part...
  15. C

    Nominal voltage for plasma?

    What is the lowest voltage required in order for Helium to become ionized? Is that equal the ionization energy in electron volt per mole (kJ/mole)? If so it's only about 24 eV for Helium. Typical voltages are around a few thousand volts for most commercial plasma globes, sometimes around 10,000...
  16. C

    How voltage amplification affects plasma flux density?

    Would a voltage amplification with the same power output increase plasma density and increase the magnetic field of the plasma, if the power output does not change? In the case of a USB plasma globe with a current flow of 300mA through 5 volt, amounts to 1,5W. CASE A: Ofcourse this...
  17. C

    Calculating volume of plasma per watt, based on ionization energy

    This is not homework, but I'm developing a new machine and doing my own research as a mechatronical engineer. I'm trying to calculate the maximum volume of Helium gas that can be ionized into plasma if I apply a power of 1 watt, where the voltage is 1000 volt and the current is 0,1mA. DATA...
  18. C

    Generating magnetic field with Plasma

    If I wanted to generate plasma to replicate the magnetic flux density of a i.e. N42 magnet, what would be the required volume of gas/plasma to achieve this? This magnet has a pull force of 12kg at the contact surface. I have chosen to use Helium, because it has the highest ionization energy...
  19. C

    Plasma volume & Ionization Energy relationship

    I'm trying to calculate the maximum volume of Helium gas that can be ionized into plasma if I apply a power of 1 watt, where the voltage is 1000 volt and the current is 0,1mA. The ionization energy for Helium is 2372,3KJ/mol (1/2372,3*10^3)mole * 2372,3*10^3 J/mole = 1 Joule 1 Watt = 1...
  20. H

    Difference Between Plasma and Radiation

    Hi all In general sometimes we talk about plasma effects on satellites and radiation effects on satellites. Can someone tell the difference between the two? Thanks and Best Regards Hamza
  21. L

    What's the excitation temp of He? How to get this?(DBD plasma)

    Hello. I've experiment, which makes plasma using He-1 under atmoshpere & room temp,it's to show how DBD plasma emission energy. As I know that high intensity wave length of He-1 are 588nm,668nm,708nm..etc. If take a formula, ln(a) is propotional to -1/(T-ex). ln(a) is some value.(a has...
  22. J

    Laser induced plasma channels and electrolasers?

    hey everyone.. I am looking to generate a laser induced plasma channel along the majority of the length of the laser beam and was looking for some advice and input... i was wondering if anyones done any experimentation with laser induced plasma channels and may have some information as to...
  23. B

    Plasma: 4th State of Matter - Properties & Magnetic Separation

    Plasma, the fourth state of matter, is a gas that consists of ions and free electrons. If you cooled plasma would it become a liquid? A solid? What would be the properties of this plasma? would you be able to magnetically separate it?
  24. K

    Graduate plasma physics program in Princeton and Univ of Michiganadvice needed

    I am looking forward to apply for Plasma Physics program in PPPL(Princeton) and Univ of Michigan. But I am not sure about what sort of recommendation letters I should send. I have one strong recomendation from my undergrad project supervisor(the project is plasma diagnostics in Hall Effect...
  25. M

    Phase-space structures in plasma turbulence

    Here is a glimpse of my current research. This is a kinetic simulation of electrostatic waves in a bump-on-tail plasma, with multiple resonances and some dissipation. Quasi-linear theory predicts a flattening of the velocity distribution over the range of resonant velocities of linearly unstable...
  26. F

    Plasma and Magnetic Fields: A Perpetual Motion Conundrum?

    I was wondering, if plasma moves moves in the same direction as a magnetic field when placed in a magnetic field, it seems that plasma would be in a perpetual state of motion if suspended inside a torus created by ring magnets, such as a tokamak. Wouldn't this violate the laws of...
  27. B

    Railgun Plasma Plume: What Causes it & How Long Does it Last?

    Hi, I've seen a video of the US navy test firing a rail gun and in the video there is a plasma plume that follows the projectile. I am unsure of what exactly is causing the plasma plume... specifically: Is it the electrical energy passing through the rails that ignites the air and...
  28. K

    Small Volume Plasma Confinement Device For Energy Storage

    Greetings: I am currently in the research phase of a project. I would like to get some feedback, opinions, and supporting data/information concerning the feasibility of a small volume (less than 1 cubic meter) plasma container device that would ideally be used to store energy up to 100...
  29. V

    Plasma in magnetic field in equilibrium

    Hello, Starting from the equilibrum equation of a steady-state plasma in a magnetic field: (1) \nabla P = \vec{J} \times \vec{B} where P = nkT is the plasma pressure, \vec{J} is the current and \vec{B} is the magnetic field, I am trying to solve for the magnetic field \vec{B} in terms of a...
  30. D

    Plasma shields like in star trek will they be possible

    I read the book Physics of The Impossible by Michio Kaku. It was there I first heard of plasma windows and I was like "hey that's like Halo and Mass Effect". The problem with plasma windows is that too much energy is needed to make it and that it would vapor your spaceship or soldier if you used...
  31. L

    Discharging circuit problems for Pulsed plasma thruster

    I have been working on a circuit (similar to car ionizer circuit) for a pulsed plasma thruster, which is able to charged up a capacitor to voltage as high as 1.8kV. I have a diode which is able to block reverse voltage up to 2kV interfaced between the charging circuit and the discharged...
  32. F

    Recent publications on plasma turbulence.

    Hey does anyone know where I can access some of these either for free or if my school has a subscription then I can access them on their network. I will be joining a research group soon on the simulation of heat transfer in a tokamak and would like to be up to date with the literature.
  33. G

    Creating plasma using thermite?

    Could thermite be used to bring certain types of matter to a plasma state? If so what materials would be easiest to render into a plasma? Inspired by the german experimental shockwave cannon from WWII... I got to wondering. If a 3 layered charge were used in such a weapon, one layer a...
  34. K

    Electron Oscillations in a Plasma - trouble with electric fields

    Homework Statement In a cold plasma (neglecting thermal pressure) the background medium is motionless and uniform for the electrons: \rho_e = \rho_{e0} + \rho_{e1} v_e = v_{e1}\hat{z} where ρ is electron density and v is velocity. Subscript 0 denotes a constant value and 1 denotes a small...
  35. N

    Dielectric constant and plasma membrane

    Hello! Electric force is inversely proportional to the dielectric constant. In a textbook, this is said to be forty-fold greater for water than the phospholipid membrane. As such, ions are unlikely to cross the plasmamembrane. I assume this has something to do with preferring to stay in...
  36. R

    Specific heat of a heavy ion plasma

    I am surprised by the result when I estimate the specific heat of the plasma produced by heavy ion collisions in the LHC: C(plasma) ~= 2e5 J/(g-K) (Details below.) This is ~1e6 times greater than C(lead)=0.13 J/(g-K) (1). Did I make a mistake? If not, can the physics experts who read this...
  37. S

    Comsol 4 Plasma Module: Temperature Limitation?

    I'm using comsol 4 for plasma modeling but I've read that this module is just for low temperature plasma, does anybody knows the temperature limitation of the plasma in this module? I mean how much is the upper limitation of plasma temperature?
  38. E

    Plasma: Wave and Phase difference

    Hi, I need someone to rephrase the question or tell me what it is actually asking for because I am not sure I understand it clearly: Consider a plasma slab of width L. k_0 is the wave number in a vacuum, and k in the wave number in the plasma, where k satisfies the dispersion relation...
  39. K

    Help Needed: Collisional-Radiative Model of Copper Plasma

    Hello everybody! I'm firstly at this forum, but need help, maybe somebody can help. please =) I need few advices at different question... 1. Can somebody give advice about good literature where clear describe collisional - radiative model of low temperature plasma(better if it is copper...
  40. B

    Estimate a lower limit for the number density of the electrons in the plasma

    Homework Statement When a returning spacecraft re-enters the atmosphere, the shock wave and the friction that it generates lead to the ionisation of gas molecules just ahead of it and around it. Because of this, during the most intense phase of deceleration, radio communication signals...
  41. G

    Plasma & the elemental table

    Where can I find a list/chart of the temperatures at which elements reach the 4th state of matter known as plasma?
  42. S

    Generating Plasma During Reentry: The Science Behind Ions in Earth's Atmosphere

    How exactly is plasma generated when space vehicles reenter Earth's atmosphere? How do the ions show up? I get how the air drag creates the initial heat, but from there I do not know. Have been searching the net for about 30min and came up with nada.
  43. S

    Hot & Cold Plasmas: Examples & Temperature

    I have a question about plasma and its temperature: Which plasmas are hot plasma and which are cold plasmas.For example ionosphere ,Lightning,polar aurorae etc.
  44. 1

    What is the quality of Kruer's book on laser plasma interactions?

    Hi, I need a book about laser plasma interactions for my thesis. I'm reading P. Gibbon book "Short Pulse Laser Interaction with Matter" and further reading the autor suggests to use Kruer book "The physics of laser plasma interaction". This book is not available in my university and before...
  45. X

    What if we created plasma that ionizes at room temperature?

    I was wondering if we could create some gaseous matter whose ionization energy is very low, so it can be fully ionized under room temperature, thus converted in plasma. I know that plasma loses energy quickly by radiation, if we could harness this radiated energy, won't this violate the...
  46. V

    How Does the Refractive Index Change with Frequency in Plasma Mode?

    Homework Statement Attached as pdf. Homework Equations Attached as pdf. The Attempt at a Solution I know that refractive index is given by n=\sqrt{\varepsilon} normally. But is it still the case when asked for n( \omega) ? If so, I've tried rearranging equation 3 for...
  47. D

    Radio-frequency plasma fun: How to characterize a plasma circuit?

    Greetings, I have shifted much of the focus of my research from thin film specifics to the plasma chamber we are using, as I was unfamiliar with the intricacies of plasma and found that a lot of the parameters we are counting on frankly could not be counted upon. I'm still green, but it's...
  48. O

    What charge is on plasma ball surface?

    When I touch the surface on plasma ball, do I receieve free electron from plasma ball? or do plasma ball take free electron from my finger? Does anyone have any suggestions? Thanks in advance for any suggestions
  49. S

    Calculation of plasma frequency and static dielectric constant

    Calculation of plasma frequency and static dielectric constant (urgent) Hello: Can anyone tell me how to measure the plasa frequency of a metal and wherher energy band gap of a metal is equal to the plasma energy of that material which is equal to (plank constant * plasma angular...
  50. S

    Regarding calculation of Plasma frequency and static dielectric constant

    Hello: I want to calculate the plasma frequency of Au, Ag, Cu and Al. But wondering what is the most precise way to calculate the plasma frequency.If anyone can help me with that it will be really appreciated. I know that Plasma Energy = √(n*e^2/(m*ε°)) = plank constant * ωp Here...
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