Development and characterization of intermediate- δ discharge with lithium coatings XP-919 Josh Kallman Final XP Review June 5, 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 Final XP Review – Intermediate delta discharge (Kallman)June 5, 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 Planned LLD position and size give ~55% density reduction N LLD /N 0 Radius of LLD tray (m) 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)

NSTX Final XP Review – Intermediate delta discharge (Kallman)June 5, Heat transport under lithium PFC conditions is not well documented Plasma SOL heat transport can follow several regimes –sheath-limited – characterized by low divertor density and high temperatures, midplane and divertor temperatures similar –conduction-limited – large parallel temperature gradients can exist, with high divertor densities and low temperatures –detached – very low divertor temperatures, high level of power radiated in the divertor region The role of recycling in heat transport, as affected by lithium, will be examined Due to increased edge temperatures and the resulting lower collisionality in the low-recycling regime, heat transport should be sheath-limited XP will attempt to observe scaling of heat transport with varying lithium PFC conditions and input power

NSTX Final XP Review – Intermediate delta discharge (Kallman)June 5, 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 utilize edge diagnostics to characterize heat transport as a function of lithium application observe changes in density, impurity, and radiation profiles –once ELMs are suppressed, scan in input power in lithium-enhanced discharges, determine heat transport scaling with power –scan in fueling if time permits attempt to obtain a value for as it relates to R 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 Final XP Review – Intermediate delta discharge (Kallman)June 5, FY09 XP detail Kolemen XP has developed suitable intermediate triangularity discharge with strike point on bull-nose tile (R~0.63) for duration of shot Run plan: –pre-Li baseline will characterize equilibrium behavior – 3 discharges heat transport of particular interest density, impurity and radiation profiles will also be measured –LITER evaporation at 15 mg/min/LITER to enter ELM suppression regime – 8 discharges 4 MW beam power determine fueling/heating profiles necessary to sustain discharge characterize how properties of new equilibrium evolve with lithium application –scan in applied beam power – 9 discharges utilize 3 different input powers: 2, 3, and 5 MW, running 3 times each for good data attempt to observe H-mode threshold observe effect, if any, on density and impurity rise in relation to power if shots do not need to repeat 3 times, add in 6 MW discharge –change fueling rate and location if time permits – 8 discharges eliminate center stack fueling to improve fueling control and reduce carbon sputtering utilize best power as determined in step above

NSTX Final XP Review – Intermediate delta discharge (Kallman)June 5, Diagnostics and analysis Key diagnostics –divertor Langmuir probes for particle fluxes and electron temperature –plunging probe for n, T data at midplane –IR cameras for divertor heat fluxes –D-α and Ly-α detectors for recycling data –QDMs to estimate lithium deposition and thickness –MIGs for divertor pressure measurements –divertor/midplane bolometers to provide radiated power measurement –XEUS/LoWEUS for time resolved impurity data –SOL reflectometer for midplane density Analysis –EFIT for equilibrium reconstruction, TRANSP for transport analysis, and edge modeling codes to determine effect of lithium on discharge parameters