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A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U NSTX-U Status and Plan Masayuki Ono NSTX-U Project Director PPPL, Princeton University In collaboration with the NSTX-U Team 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 Tsukuba U U Tokyo JAEA Hebrew U Ioffe Inst RRC Kurchatov Inst TRINITI NFRI KAIST POSTECH Seoul National U ASIPP ENEA, Frascati CEA, Cadarache IPP, Jlich IPP, Garching ASCR, Czech Rep Columbia U CompX General Atomics FIU INL Johns Hopkins U LANL LLNL Lodestar MIT Nova Photonics New York U ORNL PPPL Princeton U Purdue U SNL Think Tank, Inc. UC Davis UC Irvine UCLA UCSD U Colorado U Illinois U Maryland U Rochester U Tennessee U Washington U Wisconsin NSTX-U Supported by The First A3 Foresight Workshop on Spherical Torus (ST) Jan. 14-16, 2013 SNU, Seoul, Korea Slide 2 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U 2 Talk Outline NSTX-U Mission NSTX Experimental Overview NSTX-U Construction Status NSTX-U Experimental Plan Summary Slide 3 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U Develop plasma-material-interface (PMI) solutions for next-steps Exploit high divertor heat flux from lower-A/smaller major radius Fusion Nuclear Science/Component Test Facility (FNSF/CTF) Exploit high neutron wall loading for material and component development Utilize modular configuration of ST for improved accessibility, maintenance Extend toroidal confinement physics predictive capability Access strong shaping, high , v fast / v Alfvn, and rotation, to test physics models for ITER and next-steps (see NSTX, MAST, other ST presentations) Long-term: reduced-mass/waste low-A superconducting Demo NSTX-U Mission Elements Fusion applications of low-A spherical tokamak (ST) 3 Slide 4 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U Confinement scaling (electron transport) Non-inductive ramp-up and sustainment Divertor solutions for mitigating high heat flux Radiation-tolerant magnets (for Cu TF STs) * Includes 4MW of high-harmonic fast-wave (HHFW) heating power VECTOR (A=2.3) JUST (A=1.8) ARIES-ST (A=1.6) Low-A Power Plants Key issues to resolve for next-step STs ParameterNSTX NSTX Upgrade Fusion Nuclear Science Facility Pilot Plant Major Radius R 0 [m]0.860.941.31.6 2.2 Aspect Ratio R 0 / a 1.3 1.5 1.7 Plasma Current [MA]124 1011 18 Toroidal Field [T]0.512 32.4 3 Auxiliary Power [MW] 8 19*22 4550 85 P/R [MW/m]102030 6070 90 P/S [MW/m 2 ]0.20.40.6 1.20.7 0.9 Fusion Gain Q1 22 10 NSTX Upgrade will access next factor of two increase in performance to bridge gaps to next-step STs 4 Slide 5 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U TF OD = 40cm Previous center-stack TF OD = 20cm R TAN [cm] __________________ 50, 60, 70, 130 60, 70,120,130 70,110,120,130 n e /n Greenwald 0.95 0.72 I P =0.95MA, H 98y2 =1.2, N =5, T = 10% B T = 1T, P NBI = 10MW, P RF = 4MW 2x higher CD efficiency from larger tangency radius R TAN 100% non-inductive CD with q(r) profile controllable by: tangency radius, density, position 2x higher CD efficiency from larger tangency radius R TAN 100% non-inductive CD with q(r) profile controllable by: tangency radius, density, position New 2 nd NBI Present NBI Normalized e-collisionality e * n e / T e 2 ITER-like scaling ST-FNSF ? constant q, , NSTX Upgrade 2x higher B T and I P increases T, reduces * toward ST-FNSF to better understand confinement Provides 5x longer pulses for profile equilibration, NBI ramp-up 2x higher B T and I P increases T, reduces * toward ST-FNSF to better understand confinement Provides 5x longer pulses for profile equilibration, NBI ramp-up New center-stack 5 J. Menard, et al., Nucl. Fusion 52 (2012) 083015 NSTX Upgrade will address critical plasma confinement and sustainment questions by exploiting 2 new capabilities Slide 6 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U TF flex-bus CS Casing TF cooling lines TF Coil OH Coil PF Coil 1a PF Coil 1b PF Coil 1c CHI bus A schematic of the new center-stack and the TF joint area New TF-Flex-Bus Designed and Tested to Full Cycles Slide 7 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U The NSTX-U Inner TF Bundle Manufacturing Stages New Zn-Cl-Free Soldering Technique Developed Slide 8 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U NSTX-U Support Structural Upgrades 4x Electromagnetic Forces Slide 9 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U 9 Relocation of the 2 nd NBI beam line box from the TFTR test cell into the NSTX-U Test Cell. Slide 10 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U 10 2 nd NBI alignment performed and confirmed Slide 11 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U 11 Beam-line Component Refurbishment Ion DumpCalorimeter upgradeBending Magnet Slide 12 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U JK cap tack welded to the vacuum vessel after completing alignments, and full welding is now underway (Jan. 3, 2013) Slide 13 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U 40 Torus Isolation (Gate) Valve received TVPS valves, hardware, TMPs, and shields Spool section & supports Circular bellows Exit spool piece Rectangular bellows NBI Duct and Torus Vacuum Pumping System (TVPS) components being procured and fabricated Slide 14 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U PF 1C CHI Gap In-board Divertor Out-board Divertor HHFW Antenna Center Stack Primary Passive Plates Secondary Passive Plates NBI Armor NSTX In-Vessel View and CHI Gap Protection Enhancement Expect x 10 Higher Heat Load Into the CHI Gap Slide 15 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U New CS provides higher TF (improves stability), 3-5s needed for J(r) equilibration More tangential injection provides 3-4x higher CD at low I P : 2x higher absorption (40 80%) at low I P = 0.4MA 1.5-2x higher current drive efficiency Present NBI More tangential 2 nd NBI TSC simulation of non-inductive ramp-up from I P = 0.1MA, T e =0.5keV target at B T =1T Non-inductive ramp-up from ~0.4MA to ~1MA projected to be possible with new centerstack (CS) + more tangential 2 nd NBI 15 Slide 16 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U NSTX-U CHI Start-up Configurations X 2 Higher CHI Driven Currents Expected Slide 17 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U 28 GHz 1MW Gyrotron by U. of Tsukuba A schematic of the NSTX-U ECH/EBW launcher NSTX-U ECH/EBW System for Non-Inductive Start-Up and Sustainment Slide 18 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U Disruption probability reduced by a factor of 3 on controlled experiments Reached 2 times computed n = 1 no-wall limit of N /l i = 6.7 Lower probability of unstable RWMs at high N /l i Mode stability directly measured in experiments using MHD spectroscopy Stability decreases up to N /l i = 10 Stability increases at higher N /l i Presently analysis indicates consistency with kinetic resonance stabilization Resonant Field Amplification (RFA) vs. N /l i unstable mode J. Berkery IAEA Unstable RWM Stable / controlled RWM S.A. Sabbagh Stability control improvements significantly reduce unstable RWMs at low l i and high N ; improved stability at high N /l i 18 Slide 19 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U Disruption warning algorithm shows high probability of success Based on combinations of single threshold based tests Results ~ 98% disruptions flagged with at least 10ms warning, ~ 6% false positives False positive count dominated by near-disruptive events Disruptivity Physics results Low disruptivity at relatively high N ~ 6; N / N no-wall(n=1) ~ 1.3-1.5 Consistent with specific disruption control experiments, RFA analysis Strong disruptivity increase for q* < 2.5 Strong disruptivity increase for very low rotation Warning Algorithms S. Gerhardt IAEA All discharges since 2006 NN lili q*q* Disruptivity studies and warning analysis of NSTX database are being conducted for disruption avoidance in NSTX-U 19 Slide 20 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U Maintained stable snowflake configuration for 100-600 ms with three PF coils Maintained H-mode confinement with core carbon reduction by 50 % NSTX-U control coils will enable improved and up- down symmetric snowflake configurations Higher flux expansion (increased div wetted area) Higher divertor volume (increased div. losses) V. Soukhanovskii, NF 2009 NSTX Snowflake Divertor Configuration resulted in significant divertor heat flux reduction and impurity screening 20 Slide 21 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U With Lithium Without Lithium Lithium Improved H-mode Performance in NSTX T e Broadens, E Increases, P H Reduces, ELMs Stabilize Pre-discharge lithium evaporation (mg) T e broadening with lithium E improves with lithium R. Maingi, PRL (2011) 21 E improves with lower collisionality S. Kaye, IAEA (2012) No lithium (129239); 260mg lithium (129245) H. W. Kugel, PoP 2008 Slide 22 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U Li core concentration remained very low 0.05%. C remains dominant impurity even after massive (hundreds of milligrams) Li evaporation No apparent increase in Li nor C core concentration even at higher LLD surface temperature. Li core concentration stays well below 0.1% for LLD temperature range of 90C to 290C M. Podesta, IAEA (2012) R=135-140 cm, t=500-600 ms Liquid Solid Reason for low lithium core dilution?: Li is readily ionized ~ 6 eV Li is low recycling sticks to wall Li has high neoclassical diffusivity F. Scotti, APS (2012) 22 Slide 23 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U a) b) c) d) 2 identical shots (No ELMs) I p = 0.8 MA, P nbi ~ 4 MW high , f exp ~ 20 2, pre-discharge lithium depositions 150 mg: 141255 300 mg: 138240 T surf at the outer strike point stays below 400 C for 300 mg of Li Peaks around 800 C for 150 mg Results in a heat flux that never peaks above 3 MW/m 2 with heavy lithium evaporation Lithiated graphite T. Gray. IAEA 2012 Clear reduction in NSTX divertor surface temperature and heat flux with increased lithium evaporation 23 Slide 24 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U Radiative Liquid Lithium Divertor Proposed Based largely on the NSTX Liquid Lithium Divertor Research Flowing LL Particle Pumping Surfaces Li + Li ++ Li +++ Li 0 Heat Exchanger B0B0 Divertor Heat and Particles Flux Liquid Lithium (LL) ~ 1 l/sec LL Purification System to remove tritium, impurities, and dust Li Evap. / Ionization Li Radiative Mantle Li wall coating / condensation Li path Reduced Divertor Heat and Particle Flux Particle pumping by Li coated wall Divertor Strike Point M. Ono. IAEA 2012 First Wall / Blanket At 500C 700C 000000000000 Core Reacting Plasma Core Reacting Plasma Edge Plasma Scrape Off Layer Flowing LLD Tray 200 450 C Closed RLLD LL Out LL In RLLD 24 Slide 25 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U Design studies focusing on thin, capillary-restrained liquid metal layers Combined flow-reservoir system in soaker hose concept Building from high-heat flux cooling schemes developed for solid PFCs Optimizing for size and coolant type (Helium vs. supercritical-CO 2 ) Laboratory work establishing basic technical needs for PFC R&D Construction ongoing of LL loop at PPPL Tests of LI flow in PFC concepts in the next year Coolant loop for integrated testing proposed PPPL Liquid Metal R&D for Future PFCs For NSTX-U and Future Fusion Facilities 25 M. Jaworski et al., PPPL Valve s Impurities EM Pump s Liquid Lithium Divertor Tray (LLDT) 200C 400C Divertor Heat and Particle Flux Lithium Radiative Mantle Slide 26 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U Draft NSTX-U Research Plan Being Formulated 26 Slide 27 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U Draft NSTX-U Research Facility Plan Being Formulated 27 2014201520162017201820192020202120222023 1.5 2 MA, 1s 5s NCC coils 0.2-0.4 MA plasma gun 0.3-0.5 MA CHI 0.5-1 MA CHI New center-stack 2nd NBI Upgrade OutageAdvanced PFCs, 5s 10-20s up to 1 MA plasma gun U or L Mo divertor U + L Mo divertor Extend NBI duration or implement 2-4 MW off- axis EBW H&CD 1MW2 MW ECH/EBW Divertor cryo-pump Upward LiTER Flowing Li divertor or limiter module Li granule injector All High-Z PFCs Full toroidal flowing Li divertor HHFW straps for EHO, *AE Hot High-Z FW PFCs NCC SPA upgrade Enhanced RFA/RWM sensors DBS, PCI or other intermediate-k High k B polarimetry Divertor Thomson Dedicated EHO or *AE antenna HHFW feedthru & limiter upgrade U.S. FNSF conceptual design including aspect ratio and divertor optimization Rotation control q min control Snowflake control Control integration Diagnostics for high-Z wall studies MGI disruption mitigation tests Start-up and ramp-up Boundary physics Materials and PFCs Lithium MHD Transport & turbulence Waves and Energetic Particles Scenarios and control Slide 28 A3 Foresight Workshop on ST Jan. 14- 15, 2013 NSTX-U 28 Summary NSTX-U Aims to Develop Physics Understanding Needed for Designing Fusion Energy Development Facilities (ST- FNSF, ITER, DEMO, etc.) Develop key toroidal plasma physics understanding to be tested in unexplored, hotter ST plasmas Upgrade Project has made good progress in overcoming key design challenges Project on schedule and budget, ~45-50% complete Aiming for project completion in summer 2014 Detailed NSTX-U Research Plan is being developed