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Advanced Tokamaks FIRE to ARIES

Advanced Tokamaks FIRE to ARIES. "Prospects for Fusion Energy" AST 558 Dale Meade February 21, 2005. http://fire.pppl.gov/ast558_2005.html. Elements and Issues for a Fusion Power Plant. Requirements for the Development of Fusion Power. • General issues understood very early

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Advanced Tokamaks FIRE to ARIES

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  1. Advanced Tokamaks FIRE to ARIES "Prospects for Fusion Energy" AST 558 Dale Meade February 21, 2005 http://fire.pppl.gov/ast558_2005.html

  2. Elements and Issues for a Fusion Power Plant

  3. Requirements for the Development of Fusion Power • General issues understood very early • Reactor plasma conditions (ntE ≈ 3x1020m-3s, Ti ~ 20 keV, Q ≥ 25) - confinement (turbulence), plasma heating • Neutron Wall Loading ~ 4 MWm-2 (for economic attractiveness) - material damage ~ 40 dpa/yr with low radioactive waste - tritium breeding (TBR > 1) to complete the fuel cycle • Fusion Power Densities ( ~ 5 MWm-3, ––> p ~ 10 atm) b = 〈 p / Bc2, MHD stability and coil engineering • Plasma Wall Interaction - ~ 2 MW m-2 thermal load on wall low impurity levels, low tritium retention (< 0.5 kG-T) alpha ash removal • High-duty cycle, essentially steady-state

  4. Modern Perspective on Fusion Electric Power Plants Advanced Reactor Innovation Evaluation Studies (ARIES) carried out ~ 10 studies over 15 years Farrokh Najmabadi University of California, San Diego, La Jolla, CA ARIES Web Site: http://aries.ucsd.edu/ARIES/

  5. Increase Power Density Power density, 1/Vp What we pay for,VFPC High-Field Magnets • Little Gain Big Win • ARIES-I with 19 T at the coil (cryogenic). • Advanced SSTR-2 with 21 T at the coil (HTS). D r r > D r ~ D r < D High bootstrap, High b • 2nd Stability: ARIES-II/IV • Reverse-shear: ARIES-RS, ARIES-AT, A-SSRT2 Decrease Recirculating Power Fraction • Improvement “saturates” about Q ~ 40. • A steady-state, first stability device with Nb3Sn Tech. has a recirculating fraction about 1/2 of this goal. Directions for Improvement • Improvement “saturates” at ~5 MW/m2 peak wall loading (for a 1GWe plant). • A steady-state, first stability device with Nb3Sn technology has a power density about 1/3 of this goal.

  6. A dramatic change occurred in 1990: Introduction of the Advanced Tokamak • Our vision of a fusion system in 1980s was a large pulsed device. • Non-inductive current drive is inefficient. • Some important achievements in 1980s: • Experimental demonstration of bootstrap current (TFTR); • Development of ideal MHD codes that agreed with experimental results. • Development of steady-state power plant concepts (ARIES-I and SSTR) based on the trade-off of bootstrap current fraction and plasma b (Kessel, Jardin) • ARIES-I was still too large and too expensive: Utilize advance technologies: • Utilized high field magnets to improve the power density • Introduced SiC composite to achieve excellent safety & environmental characteristics.

  7. What is an Advanced Tokamak?

  8. Reverse Shear Regime • Requires wall stabilization (Resistive-wall modes) • Excellent match between bootstrap & equilibrium current profile at high b. • Internal transport barrier • ARIES-RS (medium extrapolation): bN= 4.8, b=5%, Pcd=81 MW (achieves ~5 MW/m2 peak wall loading.) • ARIES-AT (aggressive extrapolation): bN= 5.4, b=9%, Pcd=36 MW (high b is used to reduce peak field at magnet) Reverse Shear Plasmas Lead to Attractive Tokamak Power Plants First Stability Regime • Does Not need wall stabilization (Resistive-wall modes) • Limited bootstrap current fraction (< 65%), limited bN= 3.2 and b=2%, • ARIES-I: Optimizes at high A and low I and high magnetic field.

  9. Approaching COE insensitive of power density Approaching COE insensitive of current drive Evolution of ARIES Designs

  10. ARIES Studies (1988-2003) have Defined the Plasma Requirements for an Attractive Fusion Power Plant Plasma Exhaust Pheat/Rx ~ 100MW/m Helium Pumping Tritium Retention High Gain Q ~ 25 - 50 ntET ~ 6x1021 m-3skeV Pa/Pheat = fa ≈ 90% Low rotation Plasma Control Fueling Current Drive RWM Stabilization High Power Density Pf/V~ 6 MWm-3 ~10 atm Gn ≈ 4 MWm-2 Steady-State ~ 90% Bootstrap Lets design the smallest (cheapest) experiment to test the “critical burning plasma physics” issues.

  11. FIRE Physics Objectives Burning Plasma Physics (Conventional Inductively Driven H-Mode) Q ~10 as target, higher Q not precluded fa = Pa/Pheat ~ 66% as target, up to 83% @ Q = 25 TAE/EPM stable at nominal point, access to unstable alpha ash demonstrate alpha ash removal Advanced Toroidal Physics (100% Non-inductively Driven AT-Mode) Q ~ 5 as target, higher Q not precluded fbs = Ibs/Ip ~ 80% as target, ARIES-RS/AT≈90% bN ~ 4.0, n = 1 wall stabilized, RWM feedback Quasi-Stationary Burn Duration (use plasma time scales) Pressure profile evolution and burn control > 20 - 40 tE Alpha ash accumulation/pumping > 4 - 10 tHe Plasma current profile evolution ~ 2 to 5 tskin Divertor pumping and heat removal > 10 - 20 tdivertor First wall heat removal > 1 tfirst-wall

  12. Fusion Ignition Research Experiment (FIRE) • R = 2.14 m, a = 0.595 m • B = 10 T, (~ 6.5 T, AT) • Ip = 7.7 MA, (~ 5 MA, AT) • PICRF = 20 MW • PLHCD ≤ 30 MW (Upgrade) • Pfusion ~ 150 MW • Q ≈ 10, (5 - 10, AT) • Burn time ≈ 20s (2 tCR - Hmode) • ≈ 40s (< 5 tCR - AT) • Tokamak Cost = $350M (FY02) • Total Project Cost = $1.2B (FY02) 1,400 tonne LN cooled coils Mission: to attain, explore, understand and optimize magnetically-confined fusion-dominated plasmas

  13. FIRE is Based on ARIES-RS Vision • 40% scale model of ARIES-RS plasma • ARIES-like all metal PFCs • Actively cooled W divertor • Be tile FW, cooled between shots • Close fitting conducting structure • ARIES-level toroidal field • LN cooled BeCu/OFHC TF • ARIES-like current drive technology • • FWCD and LHCD (no NBI/ECCD) • • No momentum input • • Site needs comparable to previous • DT tokamaks (TFTR/JET). • • T required/pulse ~ TFTR ≤ 0.3g-T

  14. ARIES-RS (Q = 25) Critical Issue #1- Plasma Energy Confinement: FIRE and ITER Require Modest (2.5 to 5) Extrapolation • Tokamaks have established a solid basis for confinement scaling of the diverted H-Mode. • BtE is the dimensionless metric for confinement time projection • ntET is the dimensional metric for fusion - ntET = bB2tE = bB . BtE • ARIES-RS Power Plants require BtE only slightly larger than FIRE due high b and B. • STs require extrapolation of 200

  15. Significant Progress on Existing Tokamaks Improves FIRE (and ITER) Design Basis since FESAC and NRC Reviews • Extended H-Mode and AT operating ranges • Benefits of FIRE high triangularity, DN and moderate n/nG • Extended H-Mode Performance based ITPA scaling with reduced b degradation, and ITPA Two Term (pedestal and core) scaling (Q > 20). • Hybrid modes (AUG, DIII-D,JET) are excellent match to FIRE n/nG, and projects Q > 20. • Slightly peaked density profiles (n(0)/<n> = 1.25)enhance performance. • Elms mitigated by high triangularity, disruptions in new ITPA physics basis will be tempered somewhat.

  16. New ITPA tE Scaling Opens Ignition Regime for FIRE Unstable side Stable side • Systematic scans of tE vs b on DIII-D and JET show little degradation with b in contrast to the ITER 98(y, 2) scaling which has tE ~b-0.66 • A new confinement scaling relation developed by ITPA has reduced adverse scaling with b see eq. 10 in IAEA-CN-116/IT/P3-32. Cordey et al. • A route to ignition is now available if high bN regime can be stabilized.

  17. No He Pumping • Needs He pumping technology

  18. FIRE, The Movie Simulation of a Standard H-mode in FIRE - TSC • CTM ≈ GLF23 • m = 1 sawtooth Model - Jardin et al • other effects to be added - Jardin et al FIRE, the Movie

  19. = p2sv /T2 Note: total power requires a volume integral

  20. Critical Issue #2 - High Power Densities: Requires Significant (x10) Extrapolation in Plasma Pressure

  21. Modeling FIRE Burning Advanced Tokamak Ip = 4.5 MA BT = 6.5 T H-mode edge also simulated

  22. “Steady-State” High-b Advanced Tokamak Discharge on FIRE Pf/V = 5.5 MWm-3 Gn ≈ 2 MWm-2 B = 6.5T bN = 4.1 fbs = 77% 100% non-inductive Q ≈ 5 H98 = 1.7 n/nGW = 0.85 Flat top Duration = 48 tE = 10 tHe = 4 tcr FT/P7-23

  23. Application to ITER is also being studied as part of ITPA.

  24. The proposed RWM Coils would be in the Front Assembly of Every 3rd Port Plug Assembly RWM coils wrapped on end of Port Plug

  25. Q = 5 FIRE AT Mode is Limited by the First Wall and Vac Vess Nominal operating point • Q = 5 • Pf = 150 MW, • Pf/Vp = 5.5 MWm-3 (ARIES) • ≈ steady-state 4 to 5 tCR Physics basis improving (ITPA) • required confinement H factor and bN attained transiently • C-Mod LHCD experiments will be very important First Wall is the main limit • Improve cooling • revisit FW design Opportunity for additional improvement.

  26. Note: ITER and FIRE first wall (Be to VV) cost/PFC area ≈ equal at $0.25M/m2

  27. Cool 1st Wall OFHC TF (≤ 7 T) Additional Opportunities to Optimize FIRE for the Study of ARIES AT Physics and Plasma Technologies ARIES AT (bN ≈ 5.4, fbs ≈ 90%) 12

  28. Steps to a Magnetic Fusion Power Plant FIRE ARIES-RS ITER

  29. FIRE Status • Physics Validation Review successfully passed. March 30-31, 2004 • Pre-Conceptual Activities are completed. September 30, 2004 • Ready to begin Conceptual Design Activities. Now • FIRE is ready to be put forward as per Fusion Energy Sciences Advisory Committee recommendation • Informal international discussions are being held at the technical level • Time to begin reassessment as recommended by NRC Burning Plasma Panel

  30. AST 558:  Graduate Seminar - "Prospects for Fusion Energy" February 7 A Brief History of Fusion and Magnetic Fusion Basics -  Meade February 14 Recent JET Experiments and Science Issues -  Strachan February 21   Advanced Tokamaks FIRE to ARIES - Meade February 28   The ARIES Power Plant Studies – Jardin March 7          IFE basics and NIF  -  Mark Herrmann(LLNL) Midterms and Spring Break March 21        The FESAC Fusion Energy Plan - Goldston March 28        Fusion with High Power Lasers  –  Sethian(NRL) April 4           ITER Physics and Technology-  Sauthoff April 11          Stellarator Physics and Technology - Zarnstorff April 18          “New” Mirror Approaches for Fusion - Fisch April 25          ST Science and Technology –  Peng   May 2           FRC Science and Technology - Cohen

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