TJ-II: Biasing experiments in TJ-II: Feed back control of Zonal Flows and cross-phase effects on turbulent transport: Difference between revisions
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== Name and affiliation of proponent == | == Name and affiliation of proponent == | ||
NIFS [H. Takahashi] | NIFS [H. Takahashi] | ||
KYOTO UNIVERSITY [Sh. Ohshima] | KYOTO UNIVERSITY [Sh. Ohshima] | ||
CIEMAT [U. Losada, C. Hidalgo] | |||
CIEMAT [U. Losada,I. Voldiner, B. van Milligen, C. Hidalgo] | |||
== Details of contact person at LNF == | == Details of contact person at LNF == | ||
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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: 2 days of operation | ||
* Essential diagnostic systems: | * Essential diagnostic systems: Edge biasing and edge probes | ||
* Type of plasmas (heating configuration): | * Type of plasmas (heating configuration): ECRH & NBI | ||
* 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 | ||
* Any external equipment to be integrated? Provide description and integration needs: | * Any external equipment to be integrated? Provide description and integration needs: | ||
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[[Category:TJ-II internal documents]] | [[Category:TJ-II internal documents]] | ||
[[Category:TJ-II experimental proposals 2021]] | [[Category:TJ-II experimental proposals Spring 2021]] | ||
Latest revision as of 09:35, 18 February 2021
Experimental campaign
2021
Proposal title
TJ-II: Biasing experiments in TJ-II: Feed back control of Zonal Flows and cross-phase effects on turbulent transport
Name and affiliation of proponent
NIFS [H. Takahashi]
KYOTO UNIVERSITY [Sh. Ohshima]
CIEMAT [U. Losada,I. Voldiner, B. van Milligen, C. Hidalgo]
Details of contact person at LNF
If applicable, enter contact person here or write N/A
Description of the activity
Stellarator devices have pioneered the detection of long-range correlations, consistent with the theory of zonal flows i.e., stable modes that are driven by turbulence and regulate turbulent transport, of interest in astrophysics, atmospheric dynamics and fusion plasmas. Results in the TJ-II stellarator indicate that both turbulent and neo-classical mechanisms, and their mutual interaction, should be considered to achieve a full understanding of the impact of radial electric fields on the mechanisms for the production and suppression of edge Zonal Flows [1]. Therefore the radial electric field is a key ingredient to control the turbulent drive of zonal flows [i.e. symmetry breaking of turbulence] and the damping [i.e. influence on particle orbits].
Radial electric fields can influence the turbulent transport by energy redistribution mechanisms [2] or / and by cross-phase effects [3]. The influence of Er on the level of fluctuations has been investigated since the beginning of 90´s but its role on the cross-phase is still an open issue in the high temperature plasmas [4]. Dissipation parallel to the magnetic field creates a time delay between the plasma potential & temperature and density fluctuations. As a result the potential & temperature perturbations are phase shifted relative to the density fluctuations [non-adiabatic response]. Different mechanisms should be considered including: a) Electron–ion Coulomb collisions, b) Wave–particle interactions, c) Collisions of passing particles with trapped particles, d) Role of atomic physics via neutrals.
The goal of this proposal is twofold:
1)To explore the feasibility of active control of dynamical Zonal Flows by active feed-back experiments using biasing induced electric fields as external actuator and the amplitude of low frequency ZFs as sensor.
2)To investigate the influence of edge biasing in the cross-phase of potential and density fluctuations.
International or National funding project or entity
If applicable, enter funding here or write N/A
Description of required resources
Required resources:
- Number of plasma discharges or days of operation: 2 days of operation
- Essential diagnostic systems: Edge biasing and edge probes
- Type of plasmas (heating configuration): ECRH & NBI
- Specific requirements on wall conditioning if any:
- External users: need a local computer account for data access: yes/no
- Any external equipment to be integrated? Provide description and integration needs:
Preferred dates and degree of flexibility
Preferred dates: (format dd-mm-yyyy)