| 1. |
- Antoni, V., et al.
(författare)
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Coherent structures and anomalous transport in reversed field pinch plasmas
- 2006
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T122, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- The results leading to the identification of coherent structures emerging from the background turbulence in the edge region of the reversed field pinch experiments EXTRAP-T2R and RFX are reviewed. These structures have traits of vortices in velocity field and blobs in density, and the reconstruction of their spatial structure and of their time evolution is discussed focusing on the analysis tools applied. The role of these structures in the particle anomalous transport is addressed, showing that their collisions can contribute up to 50% the total particle losses. This process is shown to be responsible for bursts in particle flux and it is found to set a characteristic collision time, which is in agreement with the statistical properties of laminar times for particle flux bursts.
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| 2. |
- Regnoli, G., et al.
(författare)
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Observations of toroidicity-induced Alfven eigenmodes in a reversed field pinch plasma
- 2005
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- High frequency peaks in the spectra of magnetic field signals have been detected at the edge of Extrap-T2R [P. R. Brunsell, H. Bergshker, M. Cecconello, J. R. Drake, R. M. Gravestijn, A. Hedqvist, and J-A. Malmberg, Plasma Phys. Controlled Fusion, 43, 1457 (2001)]. The measured fluctuation is found to be mainly polarized along the toroidal direction, with high toroidal periodicity n and Alfvenic scaling (f proportional to B / root m(i)n(i)). Calculations for, a reversed field pinch plasma predict the existence of an edge resonant, high frequency, high-n number toroidicity-induced Alfven eigenmode with the,observed frequency scaling. In addition, gas puffing experiments show that edge density fluctuations are responsible for the rapid. changes of mode frequency. Finally a coupling with the electron drift turbulence is proposed as drive mechanism for the eigenmode.
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