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TJ-II:Transport analysis by means of the Transfer Entropy: Difference between revisions
TJ-II:Transport analysis by means of the Transfer Entropy (view source)
Revision as of 16:01, 16 February 2021
, 16 February 2021→If applicable, International or National funding project or entity
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== Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)== | == Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)== | ||
Recently, radial heat transport has been explored by means of the Transfer Entropy in TJ-II.<ref name="ref1">B. van Milligen, J. Nicolau, L. García, B. Carreras, C. Hidalgo, and the TJ-II Team, The impact of rational surfaces on radial heat transport in TJ-II, Nucl. Fusion, 57(5):056028, 2017</ref> | Recently, radial heat transport has been explored by means of the Transfer Entropy in TJ-II.<ref name="ref1">B. van Milligen, J. Nicolau, L. García, B. Carreras, C. Hidalgo, and the TJ-II Team, ''The impact of rational surfaces on radial heat transport in TJ-II'', [[doi:10.1088/1741-4326/aa611f|Nucl. Fusion, 57(5):056028, 2017]]</ref> | ||
This work makes use of spontaneously arising core electron temperature (T<sub>e</sub>) perturbations that propagate outward and shows that heat transport is not a smooth and continuous (diffusive) process, but involves mini-transport barriers associated with low-order rational surfaces and rapid non-local radial ‘jumps’. | This work makes use of spontaneously arising core electron temperature (T<sub>e</sub>) perturbations that propagate outward and shows that heat transport is not a smooth and continuous (diffusive) process, but involves mini-transport barriers associated with low-order rational surfaces and rapid non-local radial ‘jumps’. | ||
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=== 1 Power scan experiments and heat transport === | === 1 Power scan experiments and heat transport === | ||
In this experiment, we repeat the study reported in<ref name="ref2">B. van Milligen et al, A possible mechanism for confinement power degradation in the TJ-II stellarator, Submitted (2018)</ref>, consisting of an ECRH power scan in a different magnetic configuration (i.e., different from the standard configuration); ECRH power is deposited centrally and is varied from its minimum (∼200 kW) to its maximum (∼500 kW) values in around 10 steps. | In this experiment, we repeat the study reported in<ref name="ref2">B. van Milligen et al, ''A possible mechanism for confinement power degradation in the TJ-II stellarator'', Submitted (2018)</ref>, consisting of an ECRH power scan in a different magnetic configuration (i.e., different from the standard configuration); ECRH power is deposited centrally and is varied from its minimum (∼200 kW) to its maximum (∼500 kW) values in around 10 steps. | ||
We will use configurations with a relatively important low-order rational at mid radius. [[TJ-II:Electron Cyclotron Emission|Electron Cyclotron Emission]] (ECE) data are used to study heat propagation. | We will use configurations with a relatively important low-order rational at mid radius. [[TJ-II:Electron Cyclotron Emission|Electron Cyclotron Emission]] (ECE) data are used to study heat propagation. | ||
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=== 2 The effect of local shear on heat propagation === | === 2 The effect of local shear on heat propagation === | ||
Following the same method reported in <ref name="ref1"></ref>, we again use ECE to study the propagation of heat. We can modify the iota profile using the induction of Ohmic current<ref name="ref3">B. van Milligen, T. Estrada, L. García, D. López-Bruna, B. Carreras, Y. Xu, M. Ochando, C. Hidalgo, J. Reynolds-Barredo, and A. López-Fraguas, The role of magnetic islands in modifying long range temporal correlations of density fluctuations and local heat transport, Nucl. Fusion, 56(1):016013, 2016</ref> to study the impact of magnetic shear on the propagation of heat pulses. The induced Ohmic current will also lead to outward radial motion of the rational surfaces, allowing to track the effect of the low-order rational as it crosses the measurement locations of the ECE channels (and the DR). | Following the same method reported in <ref name="ref1"></ref>, we again use ECE to study the propagation of heat. We can modify the iota profile using the induction of Ohmic current<ref name="ref3">B. van Milligen, T. Estrada, L. García, D. López-Bruna, B. Carreras, Y. Xu, M. Ochando, C. Hidalgo, J. Reynolds-Barredo, and A. López-Fraguas, ''The role of magnetic islands in modifying long range temporal correlations of density fluctuations and local heat transport'', [[doi:10.1088/0029-5515/56/1/016013|Nucl. Fusion, 56(1):016013, 2016]]</ref> to study the impact of magnetic shear on the propagation of heat pulses. The induced Ohmic current will also lead to outward radial motion of the rational surfaces, allowing to track the effect of the low-order rational as it crosses the measurement locations of the ECE channels (and the DR). | ||
Unlike the discharges reported in <ref name="ref3"></ref>, it is possible, using C-mode, to obtain a stationary period of modified shear. | Unlike the discharges reported in <ref name="ref3"></ref>, it is possible, using C-mode, to obtain a stationary period of modified shear. | ||
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== If applicable, International or National funding project or entity == | == If applicable, International or National funding project or entity == | ||
Generación de Conocimiento: PGC2018-097279-B-I00 | |||
== Description of required resources == | == Description of required resources == | ||
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[[Category:TJ-II internal documents]] | [[Category:TJ-II internal documents]] | ||
[[Category:TJ-II experimental proposals]] | [[Category:TJ-II experimental proposals Spring 2018]] | ||