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== Name and affiliation of proponent == | == Name and affiliation of proponent == | ||
CIEMAT (Igor Voldiner, Boudewijn van Milligen, Ulises Losada, Marian Ochando, Carlos Hidalgo) and Croatian Research Group | |||
== Details of contact person at LNF == | == Details of contact person at LNF == | ||
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== Description of the activity == | == Description of the activity == | ||
Why do ERCH/ ICRH avoid core impurity accumulation?. Significant progress has been reported regarding the physics understanding of empirical actuators like core heating to avoid impurity accumulation, including the following mechanisms: 1) A reduction of the background density gradient, leading to a reduction of the inward (neoclassical) convection of impurities; 2) An increase of turbulent transport; 3) The amplification of core temperature screening which would be relevant in core alpha-heating regimes; 4) The development of core plasma potential flux surface asymmetries. | |||
Why fast reaction of plasma fluctuations to ECRH?. This is the (challenging) question that we want to answer including experiments in TJ-II 2019 / 20, data analysis and model validation. | |||
From the theoretical perpective we should consider different mechanisms: | |||
The role of phase space driven instabilities <ref>S. Itoh and K. Itoh Scientific Reports 2, 860 (2012)</ref>; role of fast particles on MHD stability <ref>L. García et al., Physics of Plasmas 23, 062319 (2016)</ref>; the role of plasma gradient driven instabilities <ref>E. Sánchez et al., Nucl Fusion 59, 076029 (2019)</ref> and the influence of ECRH in the turbulent drive <ref>X. Wang et al., Nucl Fusion 57, 57, 116046 (2017)</ref>. | |||
From the experimental perspective the goal is the investigation and characterization of the influence of ECRH on / off power heating in the dynamics of edge & core fluctuations and transport in the TJ-II stellarator, including: 1) Level of fluctuations, 2) Phase relation between density and potential fluctuations, 3) Turbulent ExB transport. | |||
== International or National funding project or entity == | == International or National funding project or entity == | ||
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== Description of required resources == | == Description of required resources == | ||
Required resources: | Required resources: | ||
* Number of plasma discharges or days of operation: | * Number of plasma discharges or days of operation: two days | ||
* Essential diagnostic systems: | * Essential diagnostic systems: Edge & core turbulence and transport studies | ||
* Type of plasmas (heating configuration): | * Type of plasmas (heating configuration): ECRH power on-off scan [100 – 600 kW] in H vs He plasmas | ||
* Specific requirements on wall conditioning if any: | * Specific requirements on wall conditioning if any: | ||
* External users: need a local computer account for data access: yes/no | * External users: need a local computer account for data access: yes/no |
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