Possible spectroscopic signature of wave collapse in edge plasmas

Abstract

In plasmas coupled to an external energy source like a beam of energetic electrons, one can observe the non‐linear coupling of Langmuir waves with ion sound and electromagnetic waves. This non‐linear interaction of waves changes the structural and radiative properties of plasmas. Coherent wave packets are trapped in regions of high intensity, and are subjected to a wave collapse cycle. We show that the electric field of the wave packets can modify the spectral lines emitted by hydrogen atoms. Our model for this field is a sequence of envelope solitons oscillating at the plasma frequency or the upper hybrid frequency. The calculations presented concern the Hα and Hβ Balmer lines of hydrogen and show the possible modifications of the line shapes if wave collapse conditions affect the edge plasma.

Review of recent advances in the analytical theory of Stark broadening of spectral lines in plasmas: applications to laboratory discharges and astrophysical plasmas

“…This effect was first [15]. Despite both the analytical theory of the broadening of ANY H/D line by non-quasimonochromatic Langmuir waves and the observation of this effect were achieved already in 1970s, in several recent publications their authors tried to "re-invent the wheel" [16][17][18][19][20]. Of course, these simulations of selected H/D line did not discover anything new compared to the analytical theory from 1970s, The authors of those simulations seem to be totally unaware of both the corresponding analytical theory and the observation of this effect from 1970s by Sholin's group: they did not make any reference -just as in paper [21], the authors did not refer to about half-a-hundred theoretical and experimental studies of lineshape-based diagnostics of plasma turbulence in laboratory and astrophysical plasmas published between 1970 and (including) 2017, despite this was the subject of paper [21].…”

Diagnostic of Langmuir Solitons in Plasmas Using Hydrogenic Spectral Lines

“…Moreover, the additional broadening rapidly diminished with the increase of Ne, so there would be practically no additional broadening at Ne > 10 15 cm −3 . In paper [6], Hannachi et al added a magnetic field into consideration and performed simulations at the electron density Ne = 10 13 cm −3 . However, this electron density is unrealistic (too low) for the modern tokamaks (applications to which were hoped by the authors of paper [6]), and again, the additional broadening would rapidly diminish for more realistic (higher) values of Ne.…”

“…In paper [6], Hannachi et al added a magnetic field into consideration and performed simulations at the electron density Ne = 10 13 cm −3 . However, this electron density is unrealistic (too low) for the modern tokamaks (applications to which were hoped by the authors of paper [6]), and again, the additional broadening would rapidly diminish for more realistic (higher) values of Ne. Therefore, it seems that the results by Hannachi et al [5,6] would not be useful for the experimental diagnostics of Langmuir solitons.…”

“…However, this electron density is unrealistic (too low) for the modern tokamaks (applications to which were hoped by the authors of paper [6]), and again, the additional broadening would rapidly diminish for more realistic (higher) values of Ne. Therefore, it seems that the results by Hannachi et al [5,6] would not be useful for the experimental diagnostics of Langmuir solitons. 1 Therefore, in the present paper, we perform a general study of the effects of Langmuir solitons on arbitrary spectral lines of hydrogen or hydrogen-like ions.…”