TJ-II: Evolution of LCR by HIBP and Probes

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Experimental campaign

Autumn 2021

Proposal title

Evolution of core LRC, measured by Dual HIBP, and of edge LRC, measured by probes, after Pellet Injection in ECRH and NBI plasmas

Name and affiliation of proponent

A. Melnikov, I. García-Cortés, K. McCarthy, M.A. Ochando, Nerea Panadero, Macarena Liniers and HIBP group


National Research Centre ‘Kurchatov Institute’, Moscow, Russian Federation

National Research Nuclear University ‘MEPhI’, Moscow, Russian Federation

Institute of Plasma Physics, NSC KIPT Kharkov, Ukraine

Laboratorio Nacional de Fusión, CIEMAT, Madrid, Spain

Details of contact person at LNF

I. García-Cortés

Description of the activity

It is considered that anomalous transport in toroidal magnetic confinement devices (tokamaks and stellarators) has a turbulent nature. Turbulence has a very complicated structure, containing a self-regulating mechanism - Zonal Flow (ZF) - poloidally and toroidally symmetric plasma structures intertwinned with dynamics of turbulent eddies [1]. The manifestation of a ZF is Long-range correlations (LRC), observed in both the plasma edge by dual probes [2] and in the plasma core by Dual HIBPs [3]. The perturbation of plasma density and temperature profiles after Pellet Injection (PI) in ECRH and NBI plasmas, specifically during a Pellet-induced Enhanced Confinement (PIEC) regime in NBI plasma will allow us to follow the evolution of plasma turbulence, LRCs and plasma potential in the transient regime from normal to enhanced confinement and back. Such simultaneous measurements have a strong potential to shed new light on the physical mechanisms of turbulent transport reduction in the case of a PIEC (NBI) compared to density evolution without a confinement enhancement (PI in ECRH).

International or National funding project or entity

Studies of fuelling and impurity control in the stellarators TJ-II and W7-X through the use of cryogenic and TESPEl pellets (Estudios de abastacimiento y control de impurezas en los stellarators mediante el uso de perdigones criogenicos y TESPEL", Ref: PID2020-116599RB-I00

Description of required resources

Required resources:

  • Number of plasma discharges or days of operation: 2 days
  • Essential diagnostic systems: HIBP, Langmuir Probes, Pellet Injector
  • Type of plasmas (heating configuration): ECRH and NBI
  • Specific requirements on wall conditioning if any: Good Li control for NBI plasmas
  • 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: 26-10-2021 to 30-11-2021 when HIBP probes available

References

  1. P. Diamond et al, PPCF (2005)
  2. M. A. Pedrosa et al, NF (2008)
  3. A. V. Melnikov et al NF (2017)

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