Collision-dominated plasma (stellar coronae)

  • A
  • Thread starter atomiclaser
  • Start date
  • Tags
    Plasma
In summary, the paper "Helium-like ions as powerful X-ray plasma diagnostics" explores the use of resonant, intercombination, and forbidden emission of He-like ions as a diagnostic tool for high temperature plasmas. This was discussed in the "X-ray Astronomy 2000" conference and will be published in the ASP Conference Series in 2001. The authors also discuss the distinction between thermal and nonthermal plasmas, with collision-dominated plasmas having a higher density and photoionized plasmas being in non-thermal equilibrium. However, this terminology may differ from that used in other fields of plasma physics.
  • #1
atomiclaser
9
0
TL;DR Summary
I was reading some astrophysics paper, they said "Collision-dominated plasmas (e.g. stellar coronae), photo-ionized plas-mas (e.g. AGNs) or transient plasmas (e.g. SNRs) are considered."
Does anyone know what is the difference between these plasmas? for example, temperature, density, charge state etc.
Naively, "collision-dominated " means like ion-atom charge exchange is dominant ?
The paper is "Helium-like ions as powerful X-ray plasma diagnostics"
Proceedings of “X-ray Astronomy 2000”, Palermo, Sep. 2000
ASP Conference Series, Vol. TBD (in press), 2001
R. Giacconi, L. Stella, S. Serio
[Mentors note: arXiv link at https://arxiv.org/abs/astro-ph/0012218v2]

By the way, why the resonant emission, intercombination emission and forbidden emission of He-like ions are very diagnostical tool for high temeprature plasma?
 
Last edited by a moderator:
Astronomy news on Phys.org
  • #2
I'm not an expert but collision dominated sounds like a thermal plasma (i.e. in thermal equilibrium) and photoionized sounds like non-thermal.
 
  • #3
Presumably "collision dominated" plasmas have higher density.
 
  • #4
sunrah said:
I'm not an expert but collision dominated sounds like a thermal plasma (i.e. in thermal equilibrium) and photoionized sounds like non-thermal.
could you explain more what you mean " thermal plasma (i.e. in thermal equilibrium) and photoionized sounds like non-thermal. "?
 
  • #5
sunrah said:
could you explain more what you mean " thermal plasma (i.e. in thermal equilibrium) and photoionized sounds like non-thermal. "?

I'm just guessing really.

Normally, in a gas say, high rate of collisions leads to thermal stability or local thermodynamic equilibrium, as it is the only way to distribute energy among neutral particles. I'm just guessing this is what the plasma physicists mean when they say "collision dominated".
If photoionoized is distinct from this, then I think it will be in non-thermal equilibrium, i.e. ions are colder than the electrons.

Theses two cases (thermal EQ and non thermal EQ) actually define two classes of plasmas known as thermal and nonthermal plasmas.
 
  • #6
I did my graduate work in plasma physics, but do not know anything about astrophysical plasmas. I skimmed the paper because it looked interesting, but you should know that every field has their own jargon, and the jargon in this paper is dramatically different than that used in the ionospheric/magnetospheric physics community I was in. My 'guess' as to what those terms meant was incorrect.

On page 3 of the paper - in the paragraph before section 3 - the authors basically tell you what they mean by some of those terms. They are referring to the primary ionization mechanism. The term 'collision-dominated' has nothing at all to do with thermal equilibrium. Indeed, a collisionless plasmas (such as in the Earth's magnetosphere) can be in thermal equilibrium, although for me the most interesting physics is non-equilibrium.
jason
 
  • Like
Likes NicoleJudge and sunrah

1. What is a collision-dominated plasma?

A collision-dominated plasma refers to a state of matter in which the interactions between particles are primarily governed by collisions rather than electromagnetic forces. In this state, the particles are constantly colliding and exchanging energy, leading to a highly chaotic and dynamic system.

2. How does a collision-dominated plasma form in stellar coronae?

In stellar coronae, a collision-dominated plasma forms due to the high temperatures and densities present. As the plasma is heated, the particles gain kinetic energy and begin to collide more frequently, leading to a dominance of collisional interactions over other forces such as gravity or electromagnetism.

3. What are the main properties of collision-dominated plasma in stellar coronae?

The main properties of collision-dominated plasma in stellar coronae include high temperatures (in the millions of degrees), high densities, and a highly dynamic and turbulent nature. These plasmas also exhibit strong magnetic fields and can emit high levels of X-ray radiation.

4. How do scientists study collision-dominated plasma in stellar coronae?

Scientists study collision-dominated plasma in stellar coronae through a variety of methods, including spectroscopy, imaging, and computer simulations. Spectroscopy allows researchers to analyze the emission of light from the plasma, providing information about its temperature, density, and composition. Imaging techniques, such as X-ray telescopes, can capture images of the plasma and its dynamics. Computer simulations also play a crucial role in understanding and predicting the behavior of collision-dominated plasma.

5. What is the significance of studying collision-dominated plasma in stellar coronae?

Studying collision-dominated plasma in stellar coronae is important for understanding the physical processes that occur in these extreme environments. It can also provide insights into the formation and evolution of stars and their magnetic fields. Additionally, this research has practical applications, such as in the development of fusion energy and plasma-based technologies.

Hot Threads

Recent Insights

Back
Top