TJ-II: Feed back control of Zonal Flows and turbulence in TJ-II

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Experimental campaign

2019 Autumn

Proposal title

Feed back control of Zonal Flows and turbulence

Name and affiliation of proponent

NIFS [H. Takahashi], KYOTO UNIVERSITY [Sh. Ohshima], CIEMAT [U. Losada, C. Hidalgo]

Details of contact person at LNF

Ulises Losada, Carlos Hidalgo

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. Recent 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 amplify the turbulent drive of zonal flows [i.e. symmetry breaking of turbulence] and the damping [i.e. influence on particle orbits].

The goal of this proposal is 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.

International or National funding project or entity


Description of required resources

Required resources:

  • Number of plasma discharges or days of operation: 2 experimental days
  • Essential diagnostic systems: probes and biasing
  • Type of plasmas (heating configuration):
  • 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: Feed-back system

Preferred dates and degree of flexibility

Preferred dates: 09-04-20 / 26-04-20


  1. R. Gerrú et al., NF 2019

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