The ITER divertor concept: physics and engineering design R. A. - PowerPoint PPT Presentation

The ITER divertor concept: physics and engineering design R. A. Pitts, X. Bonnin, S. Carpentier 1 , W. Dekeyser, F. Escourbiac, L. Ferrand, T. Hirai, A. S. Kukushkin 2 , A. Loarte, R. Reichle ITER Organization, CS 90 046 - 13067 St Paul Lez Durance Cedex, France 1 EIRL S. Carpentier-Chouchana, 13650 Meyrargues, France 2 Present address: NRC “Kurchatov Institute”, Moscow 123182 and National Research Nuclear University MEPhI, Moscow 115409, Russia The views and opinions expressed herein do not necessarily reflect those of the ITER Organization. @2015, ITER Organization IDM UID: 1 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Content • Recap of what the ITER W divertor looks like  Basic design features • Operational physics considerations  Baseline operating condition (note most will be covered in talk I-2, A. S. Kukushkin)  Consequence of magnetic perturbations  Transients (very brief)  Detachment control options (to be dealt with in detail in talk I-3, B. Lipschultz) • Summary of key outstanding R&D areas @2015, ITER Organization IDM UID: 2 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Recap of basic design features @2015, ITER Organization IDM UID: 3 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

The W divertor Inner vertical • ITER will begin target operations with a full- Outer vertical W armoured divertor target  Must survive to at Dome least the end of the first full DT campaign 54 divertor assemblies ~500 tons total mass ~150 m 2 W surface Pumping 4320 actively cooled slot heat flux elements Reflector Bakeable to 350  C plates Cassette body @2015, ITER Organization IDM UID: 4 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

W divertor: essential characteristics Strong outboard shaping for Baffles to limit disruption transients neutral escape to the core Dome – improve Reflector plates to pumping  less protect against strike pumping speed point excursions and required for given some measure of upstream He conc diagnostic/cassette or fuel throughput. protection Diagnostic/cassette Open pathway between divertors for neutral recirculation protection – reduction of target heat load asymmetries @2015, ITER Organization IDM UID: 5 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

W monoblocks • “Standard” technology  W blocks bonded to a CuCrZr cooling tube via a Cu interlayer Monoblock Cu interlayer CuCrZr tube @2015, ITER Organization IDM UID: 6 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

W monoblock dimensions • Still working on the final thickness to cooling tube and top surface shaping (see later) Toroidal gap (0.5 mm) Poloidal gap (0.5 mm) Thickness to cooling pipe (6 – 8 mm) @2015, ITER Organization IDM UID: 7 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Monoblock numbers • Totals, for the record (as of June 2014) OVT IVT 16 PFUs 138 monoblock/PFU 119,232 total per divertor 48,384 on the straight vertical part 0.5 o tilting axis+80º 292,194 grand total Tilting axis 313,838 with 4 spare cassettes 22 PFUs 143-146 monoblock/PFU 0.74º 172,962 total per divertor 61,182 on the straight vertical part @2015, ITER Organization IDM UID: 8 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Global shaping for transients DOME: protection against strike point OVT excursions Outer baffle toroidal chamfering for VDE protection @2015, ITER Organization IDM UID: 9 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Vertical target & monoblock shaping Worst case expected radial misalignment between toroidally neighbouring monoblocks ± 0.3 mm Global target tilt Individual 0.3 mm monoblock shaping @2015, ITER Organization IDM UID: 10 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Monoblock shaping Global target tilt Individual monoblock shaping • Full scale OVT prototype PFUs from Japan now just undergoing high heat flux testing (in Russia) and meets the geometrical tolerances (PFU-PFU radial misalignment within ± 0.3 mm) @2015, ITER Organization IDM UID: 11 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Monoblock shaping Simplest solution to hide worst case leading edge: single toroidal chamfer of height 0.5 mm Global target tilt 0.5 mm Individual monoblock shaping • Shaping ALWAYS increases plasma heat loads (reduced projected area)  e.g. for ITER outer vertical target  Global target tilt: increase by 19%  0.5 mm toroidal monoblock chamfer: increase by 37%  10 MWm -2 becomes ~15 MWm -2 @2015, ITER Organization IDM UID: 12 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Operational physics considerations @2015, ITER Organization IDM UID: 13 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Baseline operating mode • Deep vertical target with partially detached strike regions maintaining steady state peak load q  ≤ 10 MWm -2  The physics operating mode for ITER is entirely based on very extensive set of SOLPS-4.3 simulations conducted over 15 years  talk I-2 by A. S. Kukushkin A. S. Kukushkin et al. J. Nucl. Mat. 290-293 (2001) 887 A. S. Kukushkin et al. Nucl. Fusion 42 (2002) 187 Now moving to new code version A. S. Kukushkin and H. D. Pacher, PPCF 44 (2002) 931 A. S. Kukushkin et al. Nucl. Fusion 43 (2003) 716 A. S. Kukushkin et al. Fus. Eng. Design 65 (2003) 355 A. S. Kukushkin et al. J. Nucl. Mat. 337-339 (2005) 17 A. S. Kukushkin et al. Nucl. Fusion 45 (2005) 608 SOLPS-ITER A. S. Kukushkin et al. Nucl. Fusion 47 (2007) 698 A. S. Kukushkin et al. J. Nucl. Mat. 363-365 (2007) 308 A. S. Kukushkin et al. Nucl. Fusion 49 (2009) 075008 S. Wiesen et al, . J. Nucl. Mat. 463 (2015) 480 A. S. Kukushkin et al. Fus. Eng. Design 86 (2011) 2865 X. Bonnin et al., 15 th PET, 9-11 Sept. 2015 A. S. Kukushkin et al., J. Nucl. Mat. 415 (2011) 2011 A. S. Kukushkin et al. Nucl. Fusion 53 (2013) 123024 A. S. Kukushkin et al. J. Nucl. Mat. 438 (2013) S203 H. D. Pacher et al. J. Nucl. Mat. 463 (2015) 591 H. D. Pacher et al. J. Nucl. Mat. 415 (2011) S492 H. D. Pacher et al. J. Nucl. Mat. 390-391 (2009) 259 G. W. Pacher et al. Nucl. Fusion 48 (2008) 105003 G. W. Pacher et al. Nucl. Fusion 51 (2011) 083004 H. D. Pacher et al. J. Nucl. Mat. 313-316 (2003) 657 @2015, ITER Organization IDM UID: 14 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Baseline operating mode • Most work done for C divertor targets but with decision to go full W, work switched to “carbon-free” (from 2013)  Ne and N 2 impurity seeding, no W yet  assume that anything other than trace quantities unacceptable  Steady state simulations, ELM power included implicitly through P SOL , no drifts, currents (yet) 100  High performance (Q DT = 10, P SOL ~100 q ||,omp (MWm -2 ) 1 MW) of primary interest  sets limits e -1 on target heat flux 10  Most simulations fix  q ~ 3.6 mm D  = 0.3 m 2 s -1 ,   i,e = 1.0 m 2 s -1   q (omp) = 3 – 4 mm 1 0 5 10 15 20  Have studied cases with  q ~ 1 mm (r – r sep ) omp (mm) @2015, ITER Organization IDM UID: 15 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Operating window in target power flux q pk,target (MWm -2 ) • Similar operating window as for Neon Carbon exists for Ne and N  Window up to Q DT ~15 for Power handling limit q pk < 10 MWm -2 at lowest c Ne Detachment limit  For any reasonable p n , only very low c Ne required to maintain P SOL = 100 MW acceptable q pk c ne (separatrix)  ~2x core concentration of N gives same Q DT as for Ne  Simulations for  q ~3.5 mm Divertor neutral pressure (Pa) H. D. Pacher et al., J, Nucl . Mat. 463 (2015) 591 @2015, ITER Organization IDM UID: 16 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Lower limit on operating window • W source likely too high at high q pk (low p n ) Outer target: P SOL = 100 MW, c Ne,sep ~1.2% T e (eV) T i (eV) n e (10 21 m -3 ) q pk (MWm -2 ) Distance along target (m) Distance along target (m) @2015, ITER Organization IDM UID: 17 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Consequence of reduced transport? • Ok if p n high enough, BUT increased n e,sep due to higher power density  Integrated modelling indicates reduced operational window if q  ≤ 10 MWm -2 n e,sep (10 20 m -3 ) n e_sep mod [10 20 m -3 ] q  ,peak, target, (MWm -2 ) Problems likely 0.8 438 (2013) S203 A. S. Kukushkin et al., J, Nucl. Mat. 0.7 here due to 0.6 excessive W 0.5 release? 0.4 10 0.3  q (mm) 0.2 ~1.3 ~1.7 ~3.6 1 0.1 1 10 1 10 p n [Pa p n [Pa Divertor neutral pressure (Pa) Divertor neutral pressure (Pa) @2015, ITER Organization IDM UID: 18 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM

Radiation distributions (C vs. N) • N very like C (as expected) (Wm -3 ) P SOL = 100 MW #2533 #1577 N C q pk,outer = 4 MWm -2 q pk,outer = 4.5 MWm -2 c N,sep = 0.8% c C,sep = 2.0% Total P RAD,DIV = 59 MW Total P RAD,DIV = 65 MW P RAD,fuel = 17 MW P RAD,fuel = 12 MW @2015, ITER Organization IDM UID: 19 IAEA TM on Divertor Concepts, Vienna, Austria, 29 September 2015 RF2HCM