Alcator C-Mod Program Overview ( )

Transcription

1 Alcator C-Mod Program Overview ( ) Alcator C-Mod Program Advisory Committee February 4-6, 2009 E. S. Marmar for the Alcator Group Compact highperformance divertor tokamak research to establish the plasma physics and engineering necessary for a burning plasma tokamak experiment and for attractive fusion reactors.

2 Proposal for the next five years of research November 2008 October 2013 MIT portion of C-Mod support funded through Co-operative Agreement with DoE, OFES Grant period is 5 years Proposal submitted in March, 2008 Peer review (including site visit in May, 2008) Reviews were strongly positive Agreement renewed November 1, 2008 Collaborators funded separately, through grants (Universities) and Field Work Proposals (National Labs) Program assumes continued participation of collaborators at similar levels Proposal written assuming incremental funding Primarily focus this PAC meeting on program assuming guidance funding Opportunities for enhancements with increments will be presented

3 DEMO GAP Initiatives ITER ITER Baseline Inductive High Pressure Advanced Scenarios High Bootstrap Quasi-Steady State Integrated Scenarios* Energy, Particle Science & Momentum Challenges Transport H-Mode Pedestal Plasma Boundary Interactions Wave-Plasma Interactions Macroscopic Stability *Equilibrated electrons-ions, no core momentum/particle sources, RF I p drive

4 C-Mod Unique in World and US Among High Performance Divertor Tokamaks Unique in the World: High field, high performance divertor tokamak Particle and momentum source-free heating and current drive Equilibrated electrons and ions Solid high-z plasma facing components ITER level Scrape-Off-Layer/Divertor power density Approach ITER neutral opacity, radiation trapping Highest pressure and energy density plasmas Exclusive in the US : ICRF minority heating Lower Hybrid Current Drive Premier major US facility for graduate student training

5 C-Mod Plays Major Role in Education of Next Generation of Fusion Scientists Typically have ~25-30 graduate students doing their Ph.D. research on C-Mod (more students than scientists) Nuclear Science & Engineering, Physics and EECS (MIT) Collaborators also have students utilizing the facility Current total is 31 (full-time on-site) Fully involved in all aspects of our research, leading many of the experiments as session leaders MIT undergraduates participate through UROP program Host National Undergraduate Fusion Fellows during the summer

6 Collaborators are key participants in all aspects of the program Domestic Princeton Plasma Physics Lab U. Texas FRC U. Alaska UC-Davis UC-Los Angeles UC-San Diego CompX Dartmouth U. General Atomics LLNL Lodestar LANL U. Maryland MIT-PSFC Theory NYU ORNL SNLA U. Texas IFS U. Wisconsin Coordination: USBPO, TTF, ITPA International ASIPP/EAST Hefei Budker Institute Novosibirsk C.E.A. Cadarache C.R.P.P. Lausanne Culham Lab ENEA/Frascati FOM Nieuwegein, Netherlands IGI Padua IPP Garching IPP Greifswald ITER Organization Cadarache JET/EFDA JT60-U, JAEA KFA Jülich KFKI-RMKI Budapest KSTAR Korea LHD/NIFS Oxford U. Politecnico di Torino U. Toronto

7 Completing Major Maintenance and Refurbishment of the Tokamak Facility Core tokamak disassembled Complete renewal of TF coil sliding joints Numerous other upgrades, improvements Reassembly is well underway Scheduled pumpdown at beginning of May

8 Alternator Inspection Alternator (225 MVA, 0.6 GJoule) provides pulsed power for magnet systems Routine inspection completed in summer/fall 2008 by O.E.M. Several subsystems refurbished Recommendation: Do not return the rotor to service Concern about ultrasound indications However, no meaningful change in the inspection data Previous inspections in 1996 and 2003 Currently proceeding through a process to re-certify the rotor for continued safe operation Details in presentation by Bob Granetz

9 FY09 Budget Implications of Rotor Re-Certification Previously unanticipated costs in FY09 (~$1.0 M) Complete reinspection, materials samples, analysis, possible overboring Actions 1 year delay in procurement of 3 new Lower Hybrid Klystrons 6 month delay in construction of advanced 4-strap ICRF antenna Personnel decreases (1 scientist, 1 technician)* *Through attrition

10 Facility Plans and Major Enhancements Lower Hybrid upgrades Replace first launcher with advanced low-loss design ( 09) Increased net power new + spare klystrons ( 10-12) Additional launcher and 4 th MW ( 11) Standard waveguide and flanges individual alumina windows 16x4 wave guide array novel 4-way splitters

11 Facility Plans and Major Enhancements ICRF upgrades 2 new 4-strap antennas ( 09 and 10) Rotated/aligned with B Reduce/eliminate sheath induced sputtering Fast-Ferrite Tuners for all 4 transmitters (real time adaptive tuning) ( 12) Power supply/control upgrades (improved reliability) ( 13) Tuneability (40 80 MHz) for 3 rd and 4 th transmitters* *Upgrades requiring incremental funding shown in blue

12 Facility Plans and Major Enhancements (cont d) Outer divertor upgrade DEMO-like divertor ( 11) Continuous vertical plate (higher power/energy handling) Tungsten lamella plate design Controlled temperature ( C) Hydrogen isotope retention studies Non-axisymmetric coil upgrade (increased toroidal mode number flexibility, resonant magnetic perturbation) ( 13) Massively parallel computing cluster upgrade ( 12) Magnet power supply upgrades (poloidal field) ( 10 and 13) Improved control at high current, high elongation, long pulse Boron coating of RF protection, outer shelf, and secondary limiter tiles ( 09)

13 Major Diagnostic Enhancements/Upgrades Polarimetry (PPPL, UCLA) [j(r), n e (r), magnetic fluctuations] ( 09, 10) MSE upgrade (PPPL) [eliminate stress birefringence ( 09); more radial channels( 11)] Heterodyne ECE upgrade (U. Tx.) [improved views] ( 09) SOL Thomson scattering ( 10) Compact Neutral Particle Analyzer [multiple chords] ( 09) Lower Hybrid launcher reflectometer (ORNL) ( 09) ICRF antenna reflectometer (ORNL) ( 10) In-situ accelerator* [first wall analysis] ( 11) SPRED survey spectrometer (LLNL) ( 09) Fast-ion loss detector ( 13) IR camera upgrade (LANL) [divertor heat loading] ( 09) Gas puff imaging upgrades (PPPL) [edge fluctuations] ( 09, 11) Vertical viewing high harmonic ECE [LH-driven fast electrons] ( 11) Synchrotron imaging [runaway electrons] ( 13) CO 2 scattering [fluctuations, waves] ( 10) *Primarily funded through OFES Diagnostic Initiative

14 C-Mod physics regimes, machine capabilities and control tools uniquely ITER-relevant in many respects: Edge and Divertor: All high-z solid plasma facing components (key for D retention, effects on core). Divertor characteristics close to, or same as ITER (power flow, neutral and radiation opacity). Core Transport: Equilibrated ions and electrons. No core fuelling or momentum sources (will be very low on ITER). 0.0 Macro-stability: Can access ITER β range, as well as same B T and absolute pressures (important for disruption mitigation). Wave Physics: Similar tools (ICRF and LHCD) to ITER. Same B, n => same ω p, ω c, similar ω (key for Waves, LH feasibility). Pulse length: τ pulse >> τ CR (exceeds ITER). Adding noninductive CD capability (important for Steady State scenarios). Combination of these features is unique and enables integrated studies of many key questions.

15 .. C-Mod Addresses Critical Issues for ITER Integrated Scenarios: Breakdown and current rise (l i, flux consumption, vertical stability) Reference ITER scenarios for databases and modeling ITER hybrid scenarios: experimental development, understand mechanisms for maintaining q 0 >1 Profile control methods: especially j(r) with LHCD+bootstrap Integration of all regimes with ultra-high edge heat flux Core Transport: Regimes with equilibrated e-i, low momentum input, dominant electron heating Collisionality dependence of density peaking Develop common technologies for integrated modeling (frameworks, code interfaces, data structures): MDSplus is a model Pedestal Physics: L-H power threshold at low density (at ITER B, high neutral opacity) Improve predictive capability for small ELM and quiescent H- mode regimes; small ELM regimes for β N >1.3; shaping ELM control: stochastic fields with external coils Wave-Plasma Interactions: LHCD physics and coupler technology ICRF heating, current and flow drive Z, m CS3L CS2L CS1L CS1U CS2U CS3U PF1 PF2 g5 PF3 g4 g6 g3 g1 PF4 g2 PF6 PF R, m

16 C D G C-Mod Addresses Critical Issues for ITER Plasma-Boundary Interactions Tritium retention and removal: solid high Z PFCs; plasma and nuclear effects; surface modification Surface effects: ICRF-related impurity generation; boronization Power handling and impurity control: SOL transport; radiative/detached divertor. Macrostability: Disruption database (energy loss, halo current): excellent diagnostics (radiated power, surface heating, erosion, runaways) ITER applicable disruption mitigation, validate 2 and 3-D MHD codes with radiation: pioneering studies of C-Mod experiments with NIMROD/KPRAD; LH tool to seed nonthermal electron population Develop reliable disruption prediction methods: developing robust algorithms; real-time automatic mitigation implemented in Digital Plasma Control System NTM physics: effects of rotation; LHCD control/stabilization; sawtooth control Understand intermediate n AEs; damping and stability of AEs; active MHD antennas couple to intermediate n modes. Redistribution of fast particles by AEs: ICRF ion tails drive AEs unstable; excellent diagnostics (PCI, CNPA, lost ion detector) RFQ In-Situ Surface Analysis B=0 T B=0.44 T separatrix gamma or neutron detector Trajectories of 1 MeV deuteron beam from RFQ accelerator NIMROD/KPRAD Simulation: Mitigated C-Mod Disruption 0.8 ms 1.6 ms

17 Joint Experiments Coordinated through ITPA Many issues (especially for ITER) studied in close coordination with other tokamak facilities Current areas of emphasis on C-Mod H-mode access/hysteresis (TC-2, TC-3, TC-4) Transport dependence on ExB shear and momentum (TC-6) Intrinsic rotation (TC-9) ITG/TEM/ETG turbulence (TC-10) Helium transport (TC-11) ITG critical gradient and profile stiffness (TC-13) RF driven flows (TC-14) Momentum and particle pinch dependence on collisionality (TC-15) Deuterium deposition, retention (DSOL-13, DSOL-17) SOL transport, blobs, fueling (DSOL-5, DSOL-15, DSOL-16) Divertor reattachment (DSOL-20) Disruption mitigation, database, runaways, avoidance (MDC-1, MDC-15, MDC-16, MDC- 17) NTMs, Sawteeth (MDC-5, MDC-8, MDC-14) Error fields (MDC-6) TAE studies (MDC-10, MDC-11, EP-2) Non-resonant magnetic braking (MDC-12) Vertical stability and performance limits (MDC-13) Resonant magnetic perturbations, ELMs and pedestal (PEP-19) Pedestal structure, width (PEP-6, PEP-20) Pedestal control with RF (PEP-22) Small ELMs (PEP-16) Steady-state scenarios (IOS-6) Hybrid scenarios (IOS-4.1, IOS-6) ITER demo discharges (IOS-1.1, IOS-1.2, IOS-2.2) ICRF coupling (IOS-5.2)

18 C-Mod Affiliated Scientists Fully Engaged in Community Activities: BPO, ITPA, ReNew ReNew Theme I Burning Plasma Extending confinement to reactor conditions: Jerry Hughes, Dave Mikkelsen, John Rice, Bill Rowan Self-heated plasma: Ron Parker (lead), Chuck Kessel, Steve Wukitch Control and sustainment (joint with Theme II): Steve Wolfe Mitigating transient events (joint with Theme II): Bob Granetz, Val Izzo, Dennis Whyte Diagnosis (joint with Theme II): Jim Terry (lead), David Brower ReNew Theme II High Performance, Steady-State Amanda Hubbard (Theme Chair) Auxiliary systems: Randy Wilson (Lead), Miklos Porkolab Integration: Chuck Kessel, Bruce Lipschultz Validated predictive modeling: Martin Greenwald, John Wright Magnets: Joe Minervini, Leslie Bromberg, Joel Schultz Off-normal events (joint with Theme I): Bob Granetz, Val Izzo, Dennis Whyte ReNew Theme III Plasma-Material Interface Plasma-wall interactions: Brian LaBombard Plasma facing components: Bruce Lipschultz Internal components: Jim Irby, Randy Wilson, Dennis Whyte ReNew Theme IV Harnessing Fusion Power Safety: Catherine Fiore ReNew Theme V Optimizing the Magnetic Configuration Stellarator: Jeff Freidberg

19 Core Transport Major Themes Overarching: Model Testing and Code Validation Systematic and quantitative comparisons with nonlinear turbulence codes Use synthetic diagnostics (e.g. GYRO/PCI) Quantitative where codes and models are more mature Role of magnetic shear (exploit LHCD) Electron transport (esp. at low n e ) Particle and Impurity Transport How to predict fueling, density profile and impurity content? Adding laser impurity injector (multi-pulse) Now within capabilities of gyrokinetic codes Flows and Momentum Transport State of the art diagnostics (with PPPL) ICRF and LH can each drive rotation Correlations with turbulence Internal Transport Barriers Access conditions and control, especially in absence of dominant ExB Use LHCD to trigger by mod. of shear V Tor (km/s) Rotation strongly influenced by addition of LHCD s H-mode H-mode s + LHCD L-mode s R (m)

20 Pedestal Physics Major Themes (Joint OFES Milestone, FY2011) Pedestal structure and transport Effects of shaping, topology, shear on width (joint with DIII-D, NSTX) Momentum transport Gradient limits, ELMs Collisionality, topology Connection to L-mode pedestal Edge relaxation mechanisms Pedestal regulation with/without ELMS L-H transition Low density threshold scaling Helium majority plasmas Slow (2-phase) transitions improved L-mode Pedestal control Shaping, topology External fields (RMP) Applications of RF LHCD can strongly modify the pedestal Theory and simulation Role of E R Turbulence and transport (BOUT, XGC1) ELM/EDA studies (ELITE, M3D) Integral part of the 11 joint milestone Energy Confinement Strongly Correlates with Depth of E r Well H ELM-free EDA Er Depth (kv/m) DIII-D scaling R. McDermott, Phys. Plasmas (forthcoming) β Scaling of Ped. Width on C-Mod Type I ELMy H-mode In collaboration with P. Snyder (GA)

21 Plasma Boundary Major Themes Transport - central as it controls heat loads, impurities (FY10 Joint OFES milestone) Perpendicular transport Time-averaged, turbulent Parallel heat transport Divertor physics Adding suite of SOL/surface diagnostics Plasma-surface interaction - Crucial information for a reactor (high-z tiles) Fuel retention (FY09 Joint OFES milestone) Effects of RF waves/sheaths on the edge Material properties and surface conditioning First-wall development towards fusion DEMO Molybdenum and tungsten tiles DEMO-like W divertor ( C) Being designed in collaboration with PPPL

22 Waves-Plasma Interactions Major Themes Flow Drive ICRF and LHRF both demonstrated Mode-conversion ICRF both toroidal (co-) and poloidal drive LHRF counter-current toroidal drive Current Drive LHRF: efficient far off-axis current drive More power, longer pulse (in stages) ICRF: core current drive (seed current), and applications to sawtooth control Lower Hybrid physics at ITER-relevant parameters Same wave, plasma, and cyclotron frequencies Coupler and Antenna Technology Advanced low-loss LH coupler, load tolerant splitter B-aligned ICRF antenna to reduce sheath effects Model development and validation State of the art predictive models, scalable to ITER and reactors Work closely with RF-SciDAC Toroidal Velocity (km/s) ICRF Mode-Conversion Flow Drive Mode Conversion Minority Heating Δ Stored Energy/I p (kj/ma) Y. Lin, et al., Phys. Rev. Lett. 101, (2008).

23 Macroscopic Stability Major Themes Disruption avoidance/mitigation Real-time anticipation/action Extend to locked modes, density limit, high β Runaway electron amplification/suppression LHCD for fast e - seed Effects of shaping (κ) Advanced MHD simulation Non-Axisymmetric Fields Magnetic Braking (NTV theory) RMP ELM investigations (n=1) Planned upgrades to A-coil power supplies (higher δb, also n=2) ( 13) Vertical Stability Important ITER operations issue Testing high order controllers, Kalman filters, Safe scenarios Alfven Eigenmodes Active probing of stable intermediate toroidal mode number modes ICRF fast-ion induced instabilities PCI diagnostics, NOVA-K modeling (with PPPL) TAE eigenfunction comparisons: q-profile is varied to get best fit (a) (b)

24 Integrated Scenarios for ITER and Beyond By demonstrating high performance plasmas similar to the planned ITER baseline scenario (H-Mode) and advanced scenarios (also relevant to DEMO), with relevant parameters and control tools, C- Mod will address many of the same challenges as ITER. Integrates elements of all of the science topical areas For the inductive H-mode regime (q~3, β N =1.8), these include pedestal issues, high heat fluxes and RF-wall interactions. For the hybrid scenario (q~4, 50% non-inductive), we will assess whether improved confinement is still achieved in torque-free plasmas and with RF current profile control. Steady-state regime aims at full non-inductive CD, with progressively increasing bootstrap and β N, staying below no-wall limit (~3). As on ITER, achieving this requires both full power and high confinement. Will demonstrate far off-axis LHCD at same B, n e, similar frequency proposed for ITER Pulse length capability of 5 to 10 current relaxation times for fully relaxed current profiles

25 ITER H-Mode Baseline Scenario Major Themes ITER-like H-mode regimes Same pressure, β, field, Z eff, shape Particle/momentum source free (RF actuators) Divertor and wall materials and conditioning High heat flux Hydrogenic retention Impurity/particle control Core-boundary compatability ITER-relevant plasma control Similar configuration/coil-set, advanced control system I ramp-up, ramp-down Operating point control Benign fault handling Transport and stability Benchmark modeling Evaluate disruptivity/stability issues Pre-nuclear phase (e.g. H-mode access) ICRF heating during I p ramp Reduces l i and flux consumption l i 0.5s (end of current rise) V-s required Ohmic ICRH T e0 [kev], av s TSC/TRANSP resistive rise flat top Ohmic inductive 2MW ICRH Time [s]

26 Advanced Scenarios Major Themes Develop operational scenarios for ITER and beyond Hybrid (facility milestone 09) Non-inductive steady-state (very long pulse relative to skin time) ITB and double-barrier regimes LHCD current density profile control key to many of these studies Compatibility of all scenarios with pedestal, SOL and divertor Integrated modeling essential to guide the research P e (kpa) T e,t i (kev) n e (10 20 m -3 ) LHCD influences Pedestal Decreased n and ν, increased T, P ICRF only ICRF + LH T e T i R mid (m)

27 Contributions to Gap Issues Recent FESAC panel identified critical gaps on the path from ITER to DEMO that will require new initiatives Assumes successful resolution of many issues first on existing facilities and ITER C-Mod helping to resolve many of these key issues Plasma facing components: high Z metals, ultra-high SOL power densities. Off-normal events: disruption avoidance, prediction and mitigation. Plasma-wall interactions: SOL and divertor transport, erosion/redeposition, hydrogen isotope retention. Integrated, high performance plasmas: focus of integrated thrusts. Theory and predictive modeling: code benchmarking, discovery of new phenomena, iteration of theory and comparison with experiment. Measurements: new and improved diagnostic techniques. RF antennas, launchers and other internal components: advancing the understanding of coupler-edge plasma interactions, improvement of theory and modeling. Plasma modification by auxiliary systems: RF (ICRF and LHRF) for current drive, flow drive, instability control; ELM control Control: maintaining high performance advanced scenarios with fully relaxed current profile.

28 Validation: Comparing State of the Art Code Results with C-Mod Data Pedestal, Edge and Boundary XGC code being developed through SciDAC FSP Prototype Center prediction of pedestal height and width GEM, BOUT, ESEL, KN1D ELITE for MHD stability of intermediate to high n ballooning modes Waves (TORIC, AORSA) + (CQL3D, ORBIT RF, LSC) for minority tail evolution, ICH, LHCD, MCEH, MCCD, FWEH, FWCD, ICCD Synthetic diagnostic comparisons with PCI, hard X-ray and CNPA measurements. TOPICA + (TORIC) for comparisons with antenna loading and antenna electrical characteristics TOPLHA for evaluating LH Launcher coupling and design. Macroscopic Stability NIMROD + KPRAD - simulate gas puffing M3D - sawtooth reconnection and NTM stabilization NOVA-K to simulate Alfven cascades Synthetic PCI diagnostic implemented Transport and Scenario Modeling GS2, GYRO Transport, barrier simulations (internal and edge) TSC-TRANSP simulations for AT scenario development STRAHL for impurity transport Fluctuations in H-mode (~400kHz) agree with predictions for ITG from GYRO Autopower [10 32 m -4 /cm -1 ] Frequency [khz] PCI Measurement: GYRO Simulation: Nn: 28; n: 5 Nn: 16; n:10 Freq: [300, 500] khz Wavenumber [cm -1 ] shot: trange: [0.85, 0.95] sec 2πf/k ~ 4 km/sec Wavenumber [cm -1 ] [10 32 m -4 /cm -1 /Hz]

29 Milestones OFES Programmatic Joint Targets FY08: Rotation/Momentum transport (complete) FY09: Hydrogenic retention (C-Mod emphasis on high-z) FY10: Scrape-Off-Layer/Divertor power flows FY11 (anticipated): Pedestal Physics C-Mod Facility Targets (Plain English Goals) FY08 Confinement at high I p (complete) Active control of ICRF antenna (complete) FY09 Self-generated plasma rotation Hybrid advanced scenario investigation FY10 Testing model of fuel retention in first-wall Runaway electron dynamics during disruptions Accessibility conditions for small ELMs Detailed planning for the FY09 campaign is underway Ideas Forum will be held March 17-19

30 Major Facility Upgrades Calendar Year Operations Guidance Incremental (10%) Inspect: Tokmak & Altrntr. Beowulf upgrade Facility Digital Plasma Control Lower Hybrid launcher gas-puff advanced low-loss launchers EFC upgrade (higher κ) EF2 upgrade ICRF fast-ferrite prototype new 4-strap antennas fast-ferrite tuners Boundary new Beowulf Tungsten lamella tiles cryo upgrade ECDC upgrade (add vertical B) coupler reflectometer transmitter protection up additional klystrons additional klystrons antenna reflectometer Boron-coated tiles Improved PFCs 4 MW source 4 MW source additional klystron +4 MW tunable Demo-like divertor (600 C) A-Coil Upgrade 120 MHz power supply up Complete Guidance Proposed Budget

31 Major Diagnostic Upgrades Calendar Year MSE upgrades j(r) Upper Div. T.C. Fast ion loss Cf neutron source SOL Thomson Runaway electron Polarimeter: 3 channel channel 20 Channel Divertor probe arrays Accelrtr surface analysis CNPA up. CO 2 scatt. Radial correlation reflctmtr Doppler reflectmtr LH SOL reflctmtr IR Camera up. ICRF SOL reflctmtr SPRED spectrmtr Fast Diode Up. High Harmonic ECE New GPI Views VUV Spectrmtr Up. CXRS Fast Ion DNB Pwr/Contr up Guidance Proposed Budget

32 Major Progress for Fusion Science and Fusion Energy Flexible, Capable Facility Excellent Tools and Diagnostics Key Upgrades to Facility and Diagnostics Premier Facility for Student Training Unique and Complementary Contributions to Joint (National and International) Experiments Model Validation across Broad Range of Dimensional and Dimensionless parameters Key Contributions to solution of challenges for ITER and Beyond Research supported by U.S. Department of Energy, Office of Fusion Energy Sciences