Development and characterization of intermediate- δ discharge with lithium coatings XP-919 Josh Kallman XP Review - ASC Feb 2, 2009 NSTX Supported by College W&M Colorado Sch Mines Columbia U Comp-X General Atomics INEL Johns Hopkins U LANL LLNL Lodestar MIT Nova Photonics New York U Old Dominion U ORNL PPPL PSI Princeton U Purdue U SNL Think Tank, Inc. UC Davis UC Irvine UCLA UCSD U Colorado U Maryland U Rochester U Washington U Wisconsin Culham Sci Ctr U St. Andrews York U Chubu U Fukui U Hiroshima U Hyogo U Kyoto U Kyushu U Kyushu Tokai U NIFS Niigata U U Tokyo JAEA Hebrew U Ioffe Inst RRC Kurchatov Inst TRINITI KBSI KAIST POSTECH ASIPP ENEA, Frascati CEA, Cadarache IPP, Jülich IPP, Garching ASCR, Czech Rep U Quebec

NSTX ASC XP Review – Intermediate delta discharge (Kallman)Feb 2, In preparation for LLD, the need exists to benchmark a robust discharge that optimizes pumping and performance Discharges with strike point on bull-nose tile will have lower triangularity and seek to balance pumping and performance –an intermediate δ (0.55) discharge, such as , will run with the strike point just inboard of the LLD 0D pumping code (Maingi) shows expected density control from LLD –goal is highest performance discharge that will permit high LLD pumping (due to strike point proximity to LLD plate) Planned LLD position and size give ~55% density reduction N LLD /N 0 Radius of LLD tray (m)

NSTX ASC XP Review – Intermediate delta discharge (Kallman)Feb 2, Intermediate triangularity discharge will be run under varying lithium PFC and ELM conditions FY09, pre-LLD (1 day) –utilize enhanced strike point control to place strike point at R~.63 m –establish pre-lithium equilibrium baseline –run LITER at rate sufficient to suppress ELMs observe changes in density, impurity, and radiation profiles –introduce ELMs using RWM coils –scan in fueling if time permits FY10, with LLD (1 day) –compare results under LLD conditions based on suitable strike point control demonstrated in FY09 –presence of high density Langmuir probes and x-ray spectrometer will improve plasma characterization

NSTX ASC XP Review – Intermediate delta discharge (Kallman)Feb 2, FY09 XP detail Kolemen XP will develop suitable intermediate triangularity discharge with strike point on bull-nose tile Run plan: –pre-Li baseline will characterize equilibrium behavior – 3 discharges density, impurity and radiation profiles of particular interest –LITER evaporation at 40 mg/min/LITER to enter ELM suppression regime – 12 discharges determine fueling/heating profiles necessary to sustain discharge characterize properties of new equilibrium –utilize RWM coils to trigger ELMs – 6 discharges run with square waveforms of differing frequencies observe effect, if any, on density and impurity rise and relation to ELM rate –change fueling rate and location if time permits – 6 discharges eliminate center stack fueling to improve fueling control and reduce carbon sputtering Analysis: –EFIT for equilibrium reconstruction, TRANSP for transport analysis, and edge modeling codes to determine effect of lithium on discharge parameters