TJ-II: Physics of transport decoupling, an approach to measure the phase relation between density and temperature fluctuations

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Experimental campaign

2019 Autumn

Proposal title

Physics of transport decoupling: an approach to measure the phase relation between density and temperature fluctuations

Name and affiliation of proponent

IST (Igor Nedzelskiy, Carlos Silva), UWV (Mark Koepke), CIEMAT (Ulises Losada, Gregorio Martin, J. L. de Pablos, Carlos Hidalgo)

Details of contact person at LNF

Carlos Hidalgo

Description of the activity

Why is there decoupling between particle and energy transport channels at the transition to improved confinement regimes?. Physics behind uncoupled transport channels is a relevant open question for understanding both ELM control techniques (e.g. using RMP) as part of the ITER base-line scenario and the development of plasma scenarios without ELMs (e.g. I-mode). Interestingly, uncoupled transport channels has been also reported in stellarators (e.g. TJ-II [1]).

Transport channel decoupling could be driven by any mechanism that leads to a modification of the cross-phase between density and temperature fluctuations caused by changing driving conditions [[2]].

We propose to measure the phase relation between density and temperature fluctuations using a combined diagnostic based on a Retarting Field Analyzer (RFA) [3] and Langmuir probes that has been recently developed in the TJ-II stellarator.

International or National funding project or entity

Eurofusion, DOE [US]

Description of required resources

Required resources:

  • Number of plasma discharges or days of operation: 2 days [one as Principal Investigator]
  • Essential diagnostic systems: combined RFA + probe diagnostic
  • Type of plasmas (heating configuration): ECRH
  • Specific requirements on wall conditioning if any: standard TJ-II condicitions
  • External users: need a local computer account for data access: yes
  • Any external equipment to be integrated? Provide description and integration needs:Installation of the RFA + probe diagnostic by mid-December in the reciprocating drive D

Preferred dates and degree of flexibility

Preferred dates: 16-12-2019 / 20-12-2019


References

  1. C. Hidalgo et al., PPCF 46 (2004) 287A
  2. C. Hidalgo et al., PPCF 59 (2017) 014051
  3. I. Nedzelskiy et al., RSI 82 (2011) 043505

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