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TJ-II: Influence of magnetic configuration on filament dynamics: Difference between revisions
TJ-II: Influence of magnetic configuration on filament dynamics (view source)
Revision as of 10:04, 10 December 2020
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In this context, the stellarator TJ-II provides a very appropriated experimental setup to test this hypothesis. While it shares with W-7X a fully 3D SOL, it differs from it in two relevant aspects: in the first place, due to its heliac configuration and smaller size, there are regions in it with substantial curvature, closer to that found in a tokamak. Since it is equipped with a dual system of multi-probes arrays placed at two different toroidal and poloidal locations, it is posible to measure filaments in regions with different curvatures (probe B lies in a neutral to favorable curvature probe D is in an unfavorable negative curvature zone). In the second place, it does not typically feature a rational close to the edge for a typical operation setting, although one can be intruduced by selecting the right magnetic configuration. By this means, it would be posible to disentangle the effects of curvature and SOL islands on filaments. | In this context, the stellarator TJ-II provides a very appropriated experimental setup to test this hypothesis. While it shares with W-7X a fully 3D SOL, it differs from it in two relevant aspects: in the first place, due to its heliac configuration and smaller size, there are regions in it with substantial curvature, closer to that found in a tokamak. Since it is equipped with a dual system of multi-probes arrays placed at two different toroidal and poloidal locations, it is posible to measure filaments in regions with different curvatures (probe B lies in a neutral to favorable curvature probe D is in an unfavorable negative curvature zone). In the second place, it does not typically feature a rational close to the edge for a typical operation setting, although one can be intruduced by selecting the right magnetic configuration. By this means, it would be posible to disentangle the effects of curvature and SOL islands on filaments. | ||
Therefore, the goal of this research proposal is to : | |||
1. Characterize filaments and evaluate filament propagation models, already tested in tokamaks. | |||
2. Describe and understand the effect of topologic features (e.g. islands, different curvature and connection lengths, etc.) to filament characteristics. | |||
In a previous characterization of the boundary of TJ-II <ref>T. Kobayashi, U. Losada, B. Liu et al., Nuclear Fusion 59, 044006 (2019)</ref>, sufficient data for a preliminary evaluation of filaments was gathered <ref> G. Grenfell et al., to be submitted </ref>. Form this first analysis a number of additional requirements were established for a complete characterization of filaments, including: | |||
a) Radially and poloidally separated <math>I_{sat}</math> measurements to carry out correlation-based analysis of filament shape and velocity. | |||
b) Identical probeheads with similar layouts in both manipulators to provide equivalent filament measurements in regions with different curvatures. | |||
c) The best possible characterization of <math>n_e</math> and <math>T_e</math> profiles at the edge and SOL regions. | |||
d) Repeat experiments with a magnetic configuration featuring long connection lengths for several cm. after the LCFS. | |||
== International or National funding project or entity == | == International or National funding project or entity == | ||