View source for TJ-II: 2D mapping of plasma potential and density and their fluctuations in ECRH plasmas

== Experimental campaign ==
2019 Autumn

== Proposal title ==
'''2D mapping of plasma potential and density and their fluctuations in ECRH plasmas'''

== Name and affiliation of proponent ==
Kutchatov HIBP team, Kharkov HIBP team, Ciemat team

== Details of contact person at LNF ==
If applicable, enter contact person here or write N/A

== Description of the activity ==

First 2D poloidal contour plots of plasma potential and density and their fluctuations have been measured in plasmas sustained by ECRH in the TJ-II stellarator <ref> R. Sharma et al., Nuclear Fusion 20199 (submitted)</ref> <ref> A. Melnikov et al., ISHW 2019</ref>. The 2D map for the absolute plasma potential shows a local maximum in the plasma core as expected in electron root scenarios. Density fluctuations appear both at positive and negative density gradient regions, with normalized level of density fluctuations higher in the negative density gradient region. The TJ-II innovative experimental set-up developed using a dual HIBP diagnostic pave the way for model validation on core plasma potential asymmetries and particle transport under positive density gradient scenarios in the TJ-II stellarator.

We propose new experiments to expand the 2D mapping towards the whole TJ-II poloidal cross section.

== International or National funding project or entity ==
If applicable, enter funding here or write N/A

== Description of required resources ==
Required resources:
* Number of plasma discharges or days of operation: 3 days
* Essential diagnostic systems: HIBP
* Type of plasmas (heating configuration): electron root scenarios, 100_44 configuration / 100_38
* 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)

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== References ==
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[[Category:TJ-II internal documents]]
[[Category:TJ-II experimental proposals Autumn 2019]]