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

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

Igor Nedzelskiy (IST), Mark Koepke (UWV, Ulises Losada (Ciemat), Carlos Hidalgo (Ciemat)

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 / heliotrons (e.g. TJ-II ).

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 [ ].

We propose to measure the phase relation between density and temperature fluctuations using a combined Retarting Field Analyzer (RFA) and Langmuir probes that has been recently developed for TJ-II stellarator. Measurements of the phase relation will be compared with those obtained using baffle probes.

International or National funding project or entity

DOE [US], Eurofusion

Description of required resources

Required resources:

• Number of plasma discharges or days of operation:
• Essential diagnostic systems:
• 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:

Preferred dates and degree of flexibility

Preferred dates: (format dd-mm-yyyy)

References

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