Doppler spectral line shapes and apparent velocity distribution in plasmas affected by low-frequency turbulenceY. Marandet1, H. Capes2, L. Godbert-Mouret1, M. Koubiti1 and R. Stamm1
1 PIIM, Université de Provence - Centre de St-Jérôme, F-13397 Marseille, France
2 DRFC-CEA - F-13108 Saint Paul lez Durance Cedex, France
received 12 November 2004; accepted in final form 14 December 2004
published online 19 January 2005
Starting from first principles, we derive for the first time a comprehensive formalism allowing to calculate Doppler spectral line shapes emitted in plasmas affected by low-frequency turbulence. The apparent velocity distribution function (VDF) of the emitters in a turbulent plasma, deduced from spectral line analysis, is expressed in terms of the joint probability density function (PDF) of the fluctuating plasma fields. In the case where temperature fluctuations are dominant, we use analytic expressions for the PDF, allowing theoretical predictions for the apparent VDF. We show that temperature PDFs behaving asymptotically as a power law lead to a similar behaviour for the Doppler line wings.
32.70.Jz - Line shapes, widths, and shifts.
52.35.Ra - Plasma turbulence.
05.40.Fb - Random walks and Levy flights.
© EDP Sciences 2005