# What is Plasma physics: Definition and 164 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. ### Struggling With Plasma Physics Question

First, assuming, ##v \alpha e^{i(k{\pm}z - \omega t)}## I worked with the equation of motion to get: ##-i\omega v_x = -\frac{e}{m}E_x - \omega_c v_y## and ##-i\omega v_y = -\frac{e}{m}E_y + \omega_c v_x## Solving this system of equations, I end up with: ##v_x = \frac{-e}{m(\omega^2 -...
2. ### A Information for nitrogen spectra lines

I have Optical Emission Spectroscopy data on nitrogen's second positive system and first negative system. I would like to calculate the electron temperature using the line-ratio method, which is given as: k_b T_e = (E_2 - E_1) * ( ln( \frac{I_1 \lambda_1 g_2 A_2}{I_2 \lambda_2 g_1 A_1} )...
3. ### A Combined diffusion coefficient for gas mixture

Hi. I am starting to do a gas mixture simulation. I learn the fundamentals from a paper. (doi: 10.1088/0022-3727/43/2/022001) For a gas mixture (Fe vapor in Argon), the mole fraction of Fe vapor is calculated by, and the diffusion flux JFe is given by, x_ar is the mole fraction of Argon; T is...
4. ### Navigating 21st Century: Transportation & Navigation

It was after listening to podcasts on Freeman Dyson two or three years ago that I was convinced that our best bet at Earth-Moon navigating was somewhere along the lines of a nuclear-chemical pulsed transmission. And I guess the subject matter leads itself into plasma physics somehow. (Funny...
5. ### A Plotting Potential in Plasma Sheath

Hi! everyone. I'm looking to plot potential of quasi-neutral plasma as a function of length. I know that plasma potential will drop at front of the wall from particle acceleration by electric field. I assume plasma is an electrostatic and cold (less collision). However, I'm trying to plot plasma...
6. ### B Plasma recovery at wakefield accelerators

Is it possible to keep the plasma ionized almost indefinitely. No additional heating is required.
7. ### Schools What are some good science fair project ideas or resources?

I am currently a sophomore in HS, and I have a science fair project next year. I want to do something interesting- I don't want to put in barely any effort and do something that everyone has done, like 'growing plants in different light levels'. I would ideally like to do something with...
8. ### A How making the ions leave the cavity in a ion sources

Ion sources are devices that allow creating ion beams (e.g. argon ions) and to project them outside the device, for example to be further processed by a particle accelerator, or to irradiate materials or biological tissues etc. The ions are usually created by a plasma inside a cavity filled...
9. ### 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.
10. ### How to determine the minimum grid length | Numerical Plasma Physics

Summary:: I am learning particle-in-cell (PIC) python 3X code. PIC currently represents one of the most important plasma simulation tools. It is particularly suited to the study of kinetic or non-Maxwellian effects. I am learning particle-in-cell (PIC) python code. PIC currently represents one...
11. ### A Properties of Degenerate Electron Gas

Basically the thread title. For some background, I'm trying to model laser-material interactions, where I'm assuming that the laser is interacting with a free electron gas (copper). To model the interaction, I need to determine the properties of the electron gas, such as the heat capacity...
12. ### Physics Internship possibilities: Plasma physics

Hi guys. I'm a third year physics student. Next year I'll be in my final year. I'm interested in studying fusion in the future. Unfortunately I have not done plasma physics as part of my degree so I don't know much about it yet. However I'd like to do an internship abroad this summer. Ideally I...
13. ### What Are Suitable Plasma Physics Project Ideas for an Undergraduate?

Summary:: I am looking for topics to give a presentation on. Hi everyone. If this is in the wrong section feel free to move it. Anyway, as part of our lab course, on top of doing experiments we will also have to prepare a 20 minute presentation on a chosen topic on physics. This is not like...
14. ### Studying Soft skills needed for plasma physics

As the title indicates, what are some soft skills needed (math/programming/cfd softwares) do I need if I wish to pursue a masters degree in plasma/fusion physics? Also, how do you think I should go about learning them? Thank you.
15. ### I How is the viscosity of a plasma produced?

Summary: I'm interested in knowing more about instabilities within plasma. Is the viscosity of plasma produced by thermal, magnetic, or gravitational effects (or even something else)? I had the opportunity to talk with multiple Ph.D. students during the summer and was especially interested in...
16. ### Is cusp confinement the key to achieving sustainable fusion reactions?

i have researched fusion reactors. i can't find a straight answer. what is cusp confinement.
17. ### Plasma Solution Guide for Principles of Plasma Physics (Krall & Trivelpiece)

Principles of Plasma physics by Krall & Trivelpiece seems to be a well-used book in the plasma physics community, but I've never seen a solution key for the questions asked in the book. I am trying some of the problems and want to check my work. Is there such a solution key or some blog that...
18. ### Plasma Physics question: Landau Damping

I have no clear idea of this phenomenon?
19. ### A (Plasma Physics) Spatial uniformity of particle species

Early in Bellan he asks us to consider a finite-temperature plasma and assume that the ion and electron densities are initially equal and spatially uniform. He approaches the problem of calculating the Debye length by considering each species of particle, σ , as being a fluid so that the...
20. ### Studying Preparing for Plasma Physics (Jackson)

Hi, I've posted here several time because you all gave me very helpful suggestions. Let me recap briefly my situation. I apologize for the very long post. I have BS in chemical engineering but now I'm going through a MS degree in nuclear engineering. Although - given my background - I should...
21. ### How to use the Bremsstrahlung flux to analyse a medium?

I don't know where to even begin?
22. ### Schools What are interesting research topics in plasma physics now?

I'm an undergraduate student and thinking of doing a research in plasma physics. Any suggestion? I prefer to do it computationally. Most research topic in plasma physics I googled are about fusion, but do you think it's too advanced for my education level?
23. ### A CGS units confusions in plasma physics journal papers

Hi, I was wondering of those who might write papers in this field. What is the convention of units in plasma physics papers, and is this often all screwed around and you have to already understand it to understand it? I'll give you an example, because I am looking at this paper to understand...
24. ### 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...
25. ### A Physical significance of growth rate in plasma

Let us say that we have a dispersion relation curve and associated instability curve as shown below for a magnetised plasma, which have been formulated through kinetic theory. The frequencies and growth rate have been normalized w.r.t. cyclotron frequency of proton. My question is: what does...
26. ### A Small & large argument expansion of plasma dispersion function

In plasma physics we have what is known as plasma dispersion function. There are two approximation under which this function can be expanded: when the argument is less than 1, we can use power series expansion and when the argument is greater than 1 we can have asymptotic expression. My...
27. ### Magnetic field for thin plasma column confinement

I have a thin copper tube of 4.4mm inner diameter (inside a long ionizer plasma cannon) and I want to fill in with hydrogen plasma fully ionized at low temperature (100eV), what is recommended magnetic field to have the ions there without touching tha walls? The plasma life is about 0.5 seconds
28. ### 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...
29. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 1: Introduction to Plasmas

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
30. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 2: Plasma Response to fields: Fluid Equations

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
31. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 3: DC Conductivity and Negative Differential Conductivity

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
32. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 4: RF Conductivity of Plasma

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
33. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 5: RF Conductivity of Plasma Contd

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
34. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 6: Hall Effect, Cowling Effect and Cyclotron Resonance Heating

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
35. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 7: Electromagnetic Wave Propagation in Plasma

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
36. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 8: Electromagnetic Wave Propagation in Plasma Contd.

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
37. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 9: Electromagnetic Wave Propagation Inhomogeneous Plasma

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
38. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 10: Electrostatic Waves in Plasmas

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
39. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 11: Energy Flow with an Electrostatic Wave

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
40. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 12: Two Stream Instability

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
41. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 13: Relativistic electron Beam - Plasma Interaction

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
42. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 14: Cerenkov Free Electron Laser

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
43. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 15: Free Electron Laser

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
44. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 16: Free Electron Laser: Energy gain

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
45. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 17: Free Electron Laser: Wiggler Tapering and Compton Regime Operation

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
46. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 18: Weibel Instability

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
47. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 19: Rayleigh Taylor Instability

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
48. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 20: Single Particle Motion in Static Magnetic and Electric Fields

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
49. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 21: Plasma Physics Grad B and Curvature Drifts

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/
50. ### Plasma Physics: Fundamentals and Applications (NPTEL):- Lecture 22: Adiabatic Invariance of Magnetic Moment and Mirror confinement

Lectures by Prof. V.K. Tripathi and Prof. Vijayshri, IIT Delhi. Copyright strictly reserved to professors and NPTEL, Govt. Of India. Syllabus: http://www.nptel.ac.in/syllabus/syllabus.php?subjectId=115102020 Lectures: http://www.nptel.ac.in/courses/115102020/