View source for 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 (e.g. TJ-II <ref> C. Hidalgo et al., PPCF 46 (2004) 287A </ref>). 

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 [<ref> C. Hidalgo et al., PPCF 59 (2017) 014051</ref>].  

We propose to measure the phase relation between density and temperature fluctuations using a combined diagnostic based on a Retarting Field Analyzer (RFA) <ref> I. Nedzelskiy et al., RSI 82 (2011) 043505</ref> 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

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== References ==
<references /> 

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