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Reading between the lines of highly turbulent plasmas

Study shows how to identify highly turbulent plasma signatures in the broadening of the shapes of lines emitted by ions and atoms within

Date:
March 29, 2017
Source:
Springer
Summary:
Plasma, the ionised state of matter found in stars, is still not fully understood. Astrophysicists have long-since sought to develop models that can account for the turbulent motions inside plasma. Turbulences are typically detected through observation of broadened lines due to the Doppler Effect. In a new study, researchers have developed an iterative simulation model that accurately predicts changes to the line shape in the presence of strong plasma turbulence.
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Plasma, the ionised state of matter found in stars, is still not fully understood, largely due to its instability. Astrophysicists have long-since sought to develop models that can account for the turbulent motions inside plasma, based on observing line shapes emitted by atoms and ions in the plasma. Turbulences are typically detected through the observation of broadened lines due to the Doppler effect, similar to the principle behind radar. In a new study published in EPJ D, Roland Stamm from the CNRS and Aix-Marseille University, France, and colleagues develop an iterative simulation model that accurately predicts, for the first time, the changes to the line shape in the presence of strong plasma turbulence. Ultimately, the authors aim to provide a system for assessing plasma turbulence that is valid for both a stellar atmosphere and the ITER tokamak designed to generate fusion energy. Line shapes are extensively employed as a powerful diagnostic tool for detecting turbulences in stable gases and plasmas. For many years now, astrophysicists have developed and employed models that gauge the effect of turbulent motions in the broadening of line shapes due to the Doppler effect. Such models are now also being employed to understand the role of turbulences in plasmas created to harvest energy from fusion.

In this study, the authors review the effects of strong turbulence on the line shapes when the plasma is subjected to an external energy source, such as a beam of charged particles. Their model accounts for the effect of an electric field on a hydrogen atom subjected to strong turbulence within a plasma. They subsequently perform numerical simulations for various low-density plasmas, ultimately determining that the width of the hydrogen line increases in the presence of strong turbulence connected to the external energy source, shaped as a sequence of solitons. Under such conditions, the line shapes show the presence of waves oscillating at the plasma frequency. Electrostatic waves experience a cycle during which they rise to very high intensities before dissipating and reforming, drawing energy from the driver beam.


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Journal Reference:

  1. Roland Stamm, Ibtissem Hannachi, Mutia Meireni, Hubert Capes, Laurence Godbert-Mouret, Mohammed Koubiti, Joël Rosato, Yannick Marandet, Milan Dimitrijević, Zoran Simić. Line shapes in turbulent plasmas. The European Physical Journal D, 2017; 71 (3) DOI: 10.1140/epjd/e2017-70737-2

Cite This Page:

Springer. "Reading between the lines of highly turbulent plasmas: Study shows how to identify highly turbulent plasma signatures in the broadening of the shapes of lines emitted by ions and atoms within." ScienceDaily. ScienceDaily, 29 March 2017. <www.sciencedaily.com/releases/2017/03/170329102437.htm>.
Springer. (2017, March 29). Reading between the lines of highly turbulent plasmas: Study shows how to identify highly turbulent plasma signatures in the broadening of the shapes of lines emitted by ions and atoms within. ScienceDaily. Retrieved April 27, 2017 from www.sciencedaily.com/releases/2017/03/170329102437.htm
Springer. "Reading between the lines of highly turbulent plasmas: Study shows how to identify highly turbulent plasma signatures in the broadening of the shapes of lines emitted by ions and atoms within." ScienceDaily. www.sciencedaily.com/releases/2017/03/170329102437.htm (accessed April 27, 2017).