Supported by. NSTX Liquid Lithium Divertor Status, Plans, and Future Liquid Lithium R&D Needs

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1 NSTX Supported by NSTX Liquid Lithium Divertor Status, Plans, and Future Liquid Lithium R&D Needs College W&M Colorado Sch Mines Columbia U CompX 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 Illinois U Maryland U Rochester U Washington U Wisconsin H. W. Kugel (PPPL) and R. Nygren (SNL) and Team Plasma Facing Components Community Meeting MIT, Cambridge, MA, July 08-10, 2009 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

2 NSTX is Exploring and Developing Lithium-Coated Plasma Facing Components 2005: Injected lithium pellets into He discharges prior to D NBI shot 2006: LIThium EvaporatoR (LITER) deposited lithium on room-temperature center column and lower divertor 2007: Larger evaporator re-aimed to increase deposition rate on lower divertor 2008: Dual LITERs to eliminate shadowed regions on lower divertor - Also used lithium powder dropper to introduce lithium through SOL 2009: Routine use of dual LITERs - 80% of discharges now have lithium applied beforehand (between discharges) >> due to experimenter requested conditions 2010: Experiments with 20 cm wide Liquid Lithium Divertor (LLD-1) on Outer Divertor. - Lithium held by surface tension on porous molybdenum surface (Mo/SS/Cu) - Initially coated with LITER evaporators 2

3 LLD-1 Li Surface Will Be Supplied Using the 2 LITER Units LLD C Photo of LITER on probe & loaded with Li under argon ROTATABLE SHUTTER Electrically-heated stainless-steel canisters with re-entrant exit ducts Mounted 150 apart on probes behind gaps between upper divertor plates Each evaporates 1 30 mg/min with lithium reservoir at C Plumes of lithium vapor are roughly Gaussian in angular distribution 3

4 NSTX Liquid Lithium Divertor (LLD-1) Will be tested in 2010 GRAPHITE DIAGNOSTIC TILES OUTER DIVERTOR LLD-1 80 SEGMENT INNER DIVERTOR LLD-1 SEGMENT AT SNL 316-SS BRAZED ON COPPER HOLE FOR INSERTION HEATER SNL completed 6 segments (4 for installation + 2 spares) (conical shaped the copper first, then brazed 316-SS to conical shaped copper) 6 units at Plasma Process Inc for coating with flame sprayed porous molybdenum -7/09 SNL Control Rack received at NSTX, and integration in progress. Control software testing with 3 heaters in an LLD vacuum mockup. Preparations of a staging area in progress for end-to-end mockup and testing. Installation begins after NSTX 2009 Experimental Campaign -10/09. NSTX Plasma Facing Components Community Meeting (Kugel) July 08-10,

5 NSTX Plan for Testing the Potential Benefits of a Liquid Lithium Divertor (LLD) for Integrating High Plasma and PSI Performance LLD-1(2010) Short pulse test (~ ms) of LLD-1 pumping capability from 20 cm wide liquid lithium surface on Outer Divertor - Outer Divertor is LLD-1 location offering lowest technical and programmatic risk to high-performance, high-δ ST research program. - LLD-1 surface to be coated with two existing Lithium Evaporators (LITERs) LLD-2 (2011) Increase pumping capability to improve plasma performance - Improve lithium filling efficiency and longevity of active lithium surface (e. g., capillary instead of plasma-sprayed substrate). - Increase liquid lithium surface area (e. g., inner divertor). LLD-3 (2012) Test power handling scheme for long-pulse with high heat-flux - Investigate feasibility of active cooling schemes (e. g., capillary flows, swirl tubes, helium gas, hypervaportrons, evaporative cooling) - Develop concepts for filling LLD-3 during discharges (e. g., capillary flow replenishment as planned for FTU) 5

6 Liquid Lithium PFC Future R&D Needs Need to address two current impediments to installation of liquid lithium PFCs in high power devices: power handing for long pulses. ~10-20 MW/m 2, >1sec. need e-beam and ion-beam cyclic thermal stress testing of candidate concepts.» test under operating conditions and test-to-failure. liquid lithium filling and replenishment. systems demonstrating fast flow-in and flow-out. e. g., capillary, jets, etc. surfaces permitting sufficient wetting to allow Li to flow e.g., allowing flows up to +1 m from inlet. interfaces between favorable liquid transport method and PFC surface capable of handling high incident power densities. e.g., inlet and outlet pipes may receive high power densities schemes for confining liquid lithium to plasma-facing surface of PFC in presence of rapidly changing magnetic fields. e.g., porous coatings, meshes, grooves, narrow channels 6