DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2013 EXPERIMENTAL CAMPAIGN Review | Direct submission with log-in | Request submission without log-in
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Title	230: Assessment of the degree of detachment using NIR spectroscopy
Name:	Adam McLean mclean@fusion.gat.com	Affiliation:	Lawrence Livermore National Laboratory
Research Area:	Divertor & SOL Physics	Presentation time:	Requested
Co-Author(s):	V. Soukhanovskii	ITPA Joint Experiment :	No
Description:	The recent addition of a medium/high resolution near infrared (NIR) spectrometer by LLNL/PPPL to the suite of divertor diagnostics on DIII-D provides a valuable capability to diagnose spectral regions where significant emission corresponding to low temperature plasma and molecular emissions occur relevant to burning plasma studies. Key advantages of the NIR spectral region will be used to aide in development of indicators for determination of the degree of detachment similar to that of traditional emission intensity benchmarks such as the Da/Dg ratio.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Using well controlled, repeat discharges with semi- and fully detached divertor configurations, NIR spectroscopy will be acquired, with focus on observing deuterium Paschen and diatomic deuterium emissions.
Background:	The NIR (0.8-2.2 micron) region has been poorly diagnosed in tokamak divertors due to the specialty of the camera and optical fiber technology required compared to more traditional visible-range spectroscopy. The NIR region, however, is especially relevant for the integrity of the Thomson scattering measurement (which will also apply in ITER), and for study of chemical vs. physical erosion sources. To this end, a new high resolution NIR spectrometer based on a high speed (up to 900 Hz) , InGaAs photodiode array has been installed on loan from LLNL/PPPL and available for regular diagnosis of the divertor region.
Resource Requirements:	LSN with OSP near the DiMES radius with sweeps for outer leg characterization. Gas puffing for high density operation near maximum capable n/nGW before MARFE formation.
Diagnostic Requirements:	NIR spectrometer connected to tangential MDS and DTS optical chords, Extended/enhanced DTS, high resolution MDS, filtered DiMES TV, filtered Tan TV, floor LPs, compact spectrometers
Analysis Requirements:	Plasma conditions from DTS and LPs, 2-D reconstructions of D and C emission profiles for UEDGE/OEDGE simulation with EIRENE neutral modeling.
Other Requirements: