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	21: Magnitude of cross-field drifts in the Private Flux Region, divertor asymmetries and detachment
Name:	Mathias Groth groth@fusion.gat.com	Affiliation:	Aalto University
Research Area:	Divertor & SOL Physics	Presentation time:	Not requested
Co-Author(s):	Cedric Tsui, Adam McLean, Steve Allen, Tony Leonard, Max Fenstermacher, Dmitry Rudakov, Jose Boedo, Rick Moyer, Jon Watkins, Rich Groebner, Dave Hill	ITPA Joint Experiment :	No
Description:	(1) Directly measure plasma conditions, potentials, and flows of deuterons and low charge state carbon ions in the divertor regions in L-mode plasmas. Connect these measurements to previous studies in 2004 and UEDGE simulations carried out since. Measure same plasma parameters with different diagnostics and assess/determine root cause for discrepancies (e.g., DTS versus X-point RCP versus target LPs versus IRTV). Connect carbon flows to deuteron flows: what physics is the dominant driver? (2) Repeat in low-power H-mode plasmas (for RCP measurements): how do stronger (radial) gradients and ELMs affect the flow pattern and divertor asymmetries?	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	Upstream density scan in low-power L-mode (10% beam modulation) and low-power H-mode (power within RCP limit) - Density limit to determine three upstream densities for more detailed characterization - Three density points: low, high-recycling close to jsat rollover, detached - Constant density with strike point sweeps over DTS channels - 1-2 repeat discharges for spectroscopy and imaging, and data redundancy; diagnostic tweaks
Background:	Cross-field drifts in the private flux region play an instrumental role in creating in/out asymmetric divertor conditions. These drifts are predominately driven by gradients in Te in the radial direction. UEDGE simulations predict asymmetric divertor conditions, however, the database on direct measurements of the plasma potentials and flows is sparse. To exploit new capabilities in DIII-D, i.e., the swing-arm probe system in the inner divertor and the flow imaging diagnostics, repetition of parts of the 2004 divertor characterization experiment is required to fill in critical gaps. Furthermore, upgrade of the DTS and IRTV systems will elucidate physics and data discrepancy observed in the 2004 divertor characterization experiment.
Resource Requirements:	LSN with strike points on the 45-deg tiles (inner) and shelf (outer) for DTS and X-point probe measurements; large clearance (6cm) to upper outer limiter, 9 cm to outer midplane, high-density TS chords across (density) pedestal and SOL; L-mode with one NBI source, modulated, for dedicate edge measurements, co-current source; same configuration in H-mode with 1-2 sources, co-current
Diagnostic Requirements:	Swing-arm probes, flow imaging system, DTS, target LPs, midplane and X-point probes, divertor spectroscopy and tangential cameras
Analysis Requirements:	flow analysis for probes and imaging, plasma conditions from DTS and probes, 2-D reconstructions of D and C emission profiles
Other Requirements: