TJ-II:NBI1 vs. NBI2 heated plasma comparison

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Experimental campaign

Spring 2022

Proposal title

NBI1 vs. NBI2 heated plasma comparison

Name and affiliation of proponent

T. Estrada (1), M. Liniers, S. Mulas, M.A. Ochando, E. Ascasíbar, J. Hernández, A. Cappa, I. Pastor


Suggested format:


Details of contact person at LNF


Description of the activity

At TJ-II, NBI heated plasmas show differences that depend on the injection direction, co- or counter-injection (NBI1 or NBI2, respectively). Whereas the evolution of the electron temperature and density profiles are alike in the two heating schemes, the radial electric field and density turbulence profiles evolve differently, ending up in a higher density limit and higher energy content in plasmas heated with counter-NBI (NBI2). Besides, some differences in the plasma radiation profiles are detected whose evolution is presently being studied. The experimental characterization of the beams indicates that both present similar re-ionization losses and transmission [1], while NBI heating simulations performed using ASCOT [2, 3] show more direct ion losses using co-NBI heating and better efficiency using counter-NBI for the same plasma profiles. Previous experiments indicate that the differences become more noticeable as the heating power increases. In this proposal we would like to proceed with the co- vs. counter-NBI comparison aiming at the identification of the relevant physical mechanisms responsible for the experimental observations.

[1] M. Liniers et al., FED 123, 259 (2017)

[2] J.Guasp, M.Liniers, Informe técnico 761 "Comportamiento de las pérdidas instantáneas y retardadas en la inyección de neutros del TJ-II"

[3] S.Mulas et al., 1st HPC fusion workshop 2020, Simulations of neutral beam injection in TJ-II stellarator using ASCOT5"

International or National funding project or entity

Include funding here (grants, national plans)

Description of required resources

Required resources:

  • Number of plasma discharges or days of operation: one experimental day is required as several reproducible discharges at each heating scheme are needed in order to properly characterize plasma profiles (electron density, electron and ion temperature, radial electric field, radiation, etc.)
  • Essential diagnostic systems: Microwave interferometer, Thomson scattering, diamagnetic loop, Doppler reflectometer, bolometers, Hα detectors, Rogosky and Mirnov coils, SXR, IR camera at NBI2.
  • Type of plasmas (heating configuration): co-and counter-NBI heated plasmas with plasma target created by ECH in the standard magnetic configuration.
  • Specific requirements on wall conditioning if any: fresh Li is required for a good density control during the NBI phase.
  • External users: need a local computer account for data access: no
  • Any external equipment to be integrated? Provide description and integration needs:

Preferred dates and degree of flexibility

Preferred dates: (format dd-mm-yyyy)


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