TJ-II: Fast particles induced transport: ExB transport and asymmetries

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Experimental campaign

2021

Proposal title

TJ-II: Fast particles induced transport: ExB transport and asymmetries

Name and affiliation of proponent

David Zarzoso et al., / Aix Marseille University

Filip Papausek, Ulises Losada, Alvaro Cappa, Alfonso Baciero, Macerana Liniers, Marian Ochando, Enrique Ascasibar, Carlos Hidalgo and the TJ-II team / Ciemat

Alexander Melnikov and the HIBP Kurchatov team

Alexander Kozachez and the HIBP Kharkov team

Jacobo Varela / UC3M

Manuel García-Muñoz et al., / Seville University

Details of contact person at LNF

If applicable, enter contact person here or write N/A

Description of the activity

The goal of this proposal is to investigate poloidal & toroidal asymmetries of ExB turbulent transport induced by AEs including experiments in the TJ-II plasma scenarios and simulations.

Regarding simulations, a new Guiding Centre Tracking (GCT) code was recently developed to analyse the transport and losses of energetic ions in the presence of energetic-particle-driven instabilities. It was in particular applied to the case of energetic GAMs, showing the puzzling result that energetic ion transport can exhibit a chaotic behaviour [1] and also losses of energetic particles in the presence of EGAMs were characterized for the first time as anomalous losses, exhibiting a poloidal asymmetry reminiscent of the interaction between the energetic particle trajectories and the EGAM [2]. Such code was generalized to integrate the trajectories of guiding-centres in an arbitrary 3D geometry and in the presence of an arbitrary 3D electro-magnetic field. In this proposal, we intend to apply GCT to simulate trajectories of particles (thermal and energetic) in TJ-II in the presence of Alfvén eigenmodes. GCT simulations can provide the ExB transport and losses at any location of the device, which can be validated against experiments in order to determine the degree of asymmetry of the transport induced by Alfvén eigenmodes.

Regarding experiments, the dual HIBP system [3] as well as edge Langmuir probes [4] [5] have shown their capability to provide direct and simultaneous measurements of ExB transport induced by AEs at different poloidal, toroidal and radial locations in the TJ-II stellarator .

With this in mind, the strategy of the TJ-II experimental program would be:

1. Investigation of AEs localized in the edge region by means of edge probes and HIBP [reference shot 43706] and AEs identification.

2. Influence of plasma density and magnetic configuration on AEs and ExB turbulent transport simultaneously measured in the sector D4 and B2 by Langmuir probes and at different radial locations by HIBP measurements.

4. Measurements of fast ion losses at the edge of the TJ-II stellarator using a luminescent probe to monitor [6]

3. Comparative studies of plasma asymmetries of ExB transport due to AEs by using GCT code simulations and TJ-II experimental results.

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: 3

• Essential diagnostic systems: Dual Langmuir probe system in TJ-II and HIBP

• Type of plasmas (heating configuration): ECRH & NBI

• Specific requirements on wall conditioning if any: Sufficient density control for good reproducibility in NBI plasmas.

Preferred dates and degree of flexibility

Preferred dates: (format dd-mm-yyyy)

References

  1. D. Zarzoso et al 2018 Nucl. Fusion 58 106030
  2. D. Zarzoso, D. del-Castillo-Negrete 2020 J. Plasma Phys 86 795860201
  3. A.V. Melnikov et al 2010 Nucl. Fusion 50 084023
  4. U. Losada et al., Plasma Physics and Contr. Fusion 2018
  5. F. Papausek et al., Master Thesis 2021
  6. D. Jimenez Rey et al., 2008 Rev. Scientific Instruments 79 0935112008

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