Publication: Electromagnetic properties of edge turbulence in fusion plasma devices
Loading...
Identifiers
Publication date
2016-11
Defense date
2016-11-04
Authors
Tutors
Journal Title
Journal ISSN
Volume Title
Publisher
Impact
Export
Abstract
This thesis work consists of three pillars. First, the isotope dependence of long-range correlation (due to, e.g. zonal flow and GAMs) has been studied in the TJ-II stellarator and ISTTOK tokamak with dual Langmuir probes. In TJ-II, it has been found that LRC slightly decreases with isotope mass, in contrast to tokamak results. In ISTTOK, GAM amplitude has been found to be higher in D than H dominated plasmas, in agreement with other tokamak results.
Using biorthogonal decomposition (BOD), GAM and low frequency coherent modes were separated; their spectral and spatial structure properties were studied. In addition, measurements of Reynolds stress and Maxwell stress have been made using an electromagnetic probe during L-H transition in TJ-II. Second, macroscale flows and non-diffusive behavior of particle dynamics have been found around magnetic islands in TJ-II and RFX-mod with the analysis of long-range spatial and temporal correlation (Hurst exponent). In TJ-II, during dynamic configuration scan experiments, rational surfaces have been found to affect the development of long-range spatial and temporal correlation. In RFX-mod, LRC has been detected at both sides of the m=0 island. The possible relation between long-range temporal correlation (Hurst exponent) and the phase angle of magnetic perturbation was also studied.
Third, a new strategy for studying plasma potential asymmetries in magnetic flux surface has been developed based on edge electrode biasing and probe measurements in TJ-II.
Description
Joint European Doctorate and Network in Fusion Science and
Engineering (Università degli Studi di Padova)
Keywords
Nuclear fusion, Fusion plasma, Electromagnetic properties, Stellarator TJ-II, Tokamak ISTTOK