Turbulence in the SOL of ASDEX and W7-AS

M. Endler, L. Giannone, K. McCormick, H. Niedermeyer, A. Rudyj, G. Theimer, N. Tsois, S. Zoletnik

Research output: Contribution to journalArticle

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Abstract

Electrostatic fluctuations have been measured in the scrape-off layer of ASDEX and W7-AS by Langmuir probes and by observation of Hα light and light emitted from a fast Li atom beam with high spatial and temporal resolution. It was demonstrated that these fluctuations contribute a significant, if not dominant, fraction of the anomalous radial particle transport. The basic properties of the fluctuations are the same in both experiments. A model for an instability mechanism specific to the SOL is presented including density, temperature and electric potential fluctuations. From this model mixing length estimates for the radial transport and resulting density and pressure gradients in the SOL are derived and compared to measurements in the mid-plane and in the divertor of ASDEX. In spite of several simplifications in the model a quantitative agreement up to factors of 1-3 and a qualitative agreement for variations of discharge parameters is achieved between the model predictions and the measurements. Data from poloidal multi-pin probe arrays are decomposed into a sum of spatial-temporal 'events' by means of a fitting procedure. Centres of selected events serve as reference points for the analysis of the dynamics in their surroundings. Averaging shows that positive and negative potential events appear mostly in pairs with the E × B drift in between directed radially outward.

Original languageEnglish
Pages (from-to)610-616
Number of pages7
JournalPhysica Scripta
Volume51
Issue number5
Publication statusPublished - May 1995

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Turbulence
turbulence
Fluctuations
Probe
Particle Transport
Reference Point
Electric Potential
Pressure Gradient
Electrostatics
Prediction Model
Simplification
Anomalous
Averaging
electrostatic probes
simplification
temporal resolution
pressure gradients
Model
spatial resolution
electrostatics

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Endler, M., Giannone, L., McCormick, K., Niedermeyer, H., Rudyj, A., Theimer, G., ... Zoletnik, S. (1995). Turbulence in the SOL of ASDEX and W7-AS. Physica Scripta, 51(5), 610-616.

Turbulence in the SOL of ASDEX and W7-AS. / Endler, M.; Giannone, L.; McCormick, K.; Niedermeyer, H.; Rudyj, A.; Theimer, G.; Tsois, N.; Zoletnik, S.

In: Physica Scripta, Vol. 51, No. 5, 05.1995, p. 610-616.

Research output: Contribution to journalArticle

Endler, M, Giannone, L, McCormick, K, Niedermeyer, H, Rudyj, A, Theimer, G, Tsois, N & Zoletnik, S 1995, 'Turbulence in the SOL of ASDEX and W7-AS', Physica Scripta, vol. 51, no. 5, pp. 610-616.
Endler M, Giannone L, McCormick K, Niedermeyer H, Rudyj A, Theimer G et al. Turbulence in the SOL of ASDEX and W7-AS. Physica Scripta. 1995 May;51(5):610-616.
Endler, M. ; Giannone, L. ; McCormick, K. ; Niedermeyer, H. ; Rudyj, A. ; Theimer, G. ; Tsois, N. ; Zoletnik, S. / Turbulence in the SOL of ASDEX and W7-AS. In: Physica Scripta. 1995 ; Vol. 51, No. 5. pp. 610-616.
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