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Expected Loads on ICRH Antenna A. Loarte with input from M. Sugihara, M. Shimada, and many others

Expected Loads on ICRH Antenna A. Loarte with input from M. Sugihara, M. Shimada, and many others. Radiation loads to First Wall Plasma Fluxes to First Wall in steady state and ELMs and scaling in ICRH shadow Plasma Fluxes to First Wall associated with ICRH heating and scaling in ICRH shadow

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Expected Loads on ICRH Antenna A. Loarte with input from M. Sugihara, M. Shimada, and many others

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  1. Expected Loads on ICRH AntennaA. Loartewith input from M. Sugihara, M. Shimada, and many others A. Loarte lCRH Interface Review Meeting 10 June 2008 1

  2. Radiation loads to First Wall Plasma Fluxes to First Wall in steady state and ELMs and scaling in ICRH shadow Plasma Fluxes to First Wall associated with ICRH heating and scaling in ICRH shadow Plasma Fluxes to First Wall during disruptions Overview ICRH Antenna will be subject to similar fluxes as the First Wall (some scaled down by being recessed) besides those associated with ICRH heating Ramp-up/down phases to be included A. Loarte lCRH Interface Review Meeting 10 June 2008 2

  3. 6.0 7.0 5.0 L(m) 8.0 4.0 9.0 3.0 10.0 2.0 1.0 Radiation & CX Fluxes • Radiated Fluxes to wall for QDT = 10 • Pedge > 1.3 PL-H  Prad < 85 MW qrad < 0.25 MWm-2 (peaking <2) • qcx < 0.25 MWm-2 (peaking < 2) • Radiated fluxes during steady-state Marfes (Prad = 150 MW) qrad < 0.6 MWm-2 (peaking < 3) A. Loarte lCRH Interface Review Meeting 10 June 2008 3

  4. Lipschultz QDT = 10 steady plasma loads (I) • All divertor tomakaks measure plasma particle fluxes (II B) to the main wall • Extrapolated plasma flux to the main wall in ITER 1.0 - 7 .0 1023 s-1 (1-5 % of Gdiv) Lipschultz IAEA 2000 A. Loarte lCRH Interface Review Meeting 10 June 2008 4

  5. QDT = 10 steady-state plasma loads (II) • Range of values of plasma parameters near field line contacting the wall (4-6 cm from separatrix at outer midplane) • Te,w = 10-20 eV, Ti,w/Te,w ~ 2, nw = 0.5-1.5 1019m-3 • qIIw-mp < 5.0 MWm-2 • VSOL = 30-100 ms-1 lo,mp = 0.04-0.17 m (for Lc = 60m) • Methodology to derive values in the shadow of antenna Rmp,an > Rmp,w (Lan = Wan/cos a ~2.0 m) • Convective far SOL transport • qlIan = qIIw-omp exp(-(Rmp,an-Rmp,w)/lan) • lan = lo,mp* Lan/LC ~ 1/30 * lo,mp • Diffusive far SOL transport • qlIan = qIIw-omp exp(-(Rmp,an-Rmp,w)/lan)*(Lan/LC)1/2 ~ 1/5.5 * qIIw-omp exp(-(Rmp,an-Rmp,w)/lan) • lan = lo,omp* (Lan/LC)1/2 ~1/5.5 * lo,mp qperp l Lan A. Loarte lCRH Interface Review Meeting 10 June 2008 5

  6. QDT = 10 ELM outer wall loads (I) • Steady-State and instant energy fluxes for controlled and uncontrolled ELMs near field line contacting the wall (4-6 cm from separatrix at outer midplane) • EIIw-mp < 0.6 MJm-2&12.5 MJm-2 • <qIIw-mp> < 16 MWm-2&16 MWm-2 • qIIw-mp for Dt < 0.5 s < 22 MWm-2 (overlap of ELMs) • lo,mp = 0.025-0.09 m (for Lc = 60m) • Methodology to derive values in the shadow of antenna Rmp,an > Rmp,w (Lan = Wan/cos a ~2.0 m) • Convective far SOL transport • qlIan = qIIw-omp exp(-(Rmp,an-Rmp,w)/lan) • lan = lo,mp* Lan/LC ~ 1/30 * lo,mp • Diffusive far SOL transport • qlIan = qIIw-omp exp(-(Rmp,lim-Rmp,w)/lan)*(Lan/LC)1/2 ~ 1/5.5 * qIIw-ompqIIw-omp exp(-(Rmp,an-Rmp,w)/lan) • lan = lo,omp* (Lan/LC)1/2 ~1/5.5 * lo,mp A. Loarte lCRH Interface Review Meeting 10 June 2008 6

  7. QDT = 10 ELM outer wall loads (II) • Precise value of energy flux on the wall depends on many parameters : plasma parameters at filament detachment, radial propagation velocities, losses IIB, duration of power pulse (losses IIB, filament dimension, propagation velocity) which are poorly known • Estimate for ITER based on simple model + uncertainties Fundamenski PPCF’06 A. Loarte lCRH Interface Review Meeting 10 June 2008 7

  8. QDT = 10 ELM outer wall loads (III) n = 20 Snyder NF’04 • ELM wall fluxes mainly on outer wall • Full poloidal extent typically ~ 25-50% distance between filaments • Expected values for ITER ITER (from Snyder results in NF’04) : • distance between filaments (m) ~ 15/n • full filament poloidal width (m) = (3.5-7)/n A. Loarte lCRH Interface Review Meeting 10 June 2008 8

  9. W = 0.25 <EELM> = 0.32 EELMmax W = 0.5 <EELM> = 0.59 EELMmax QDT = 10 ELM outer wall loads (IV) • Typical ELM power footprint FWHM/separation = 0.25-0.5 • ELMs impact randomly on the main wall  decreases of average heat load by ELMs • Periods with consecutive ELMs hitting the same place < 0.5 s A. Loarte lCRH Interface Review Meeting 10 June 2008 9

  10. qIIan < 20 MWm-2 typically up to 5 cm in front of antenna ICRH Loads • Calculations of power fluxes near the antenna show typical loads of less than 20 MWm-2 along the field line (value depends on assumptions on density convection in front of antenna) Report TW6-TPP-RFPFCCOUPL(L. Colas, et al. & PSI=2008) A. Loarte lCRH Interface Review Meeting 10 June 2008 10

  11. Energy Load Conditions during Major Disruptions (I) A. Loarte lCRH Interface Review Meeting 10 June 2008 11

  12. Energy Load Conditions during Major Disruptions (II) • Methodology to derive values in the shadow of antenna Rmp,an > Rmp,sep (Lan = Wan/cos a ~2.0 m) • Convective far SOL transport • ElIan = EIIsep exp(-(Rmp,an-Rmp,sep)/lan) • lan = lo,mp* Lan/LC • Diffusive far SOL transport • ElIan = EIIw-omp exp(-(Rmp,an-Rmp,sep)/lan)*(Lan/LC)1/2 • lan = lo,omp* (Lan/LC)1/2 A. Loarte lCRH Interface Review Meeting 10 June 2008 12

  13. Energy load due to mitigation by massive gas injection *) DIII-D, C-MOD experiments indicate smaller peaking factor (<2), but further confirmation is necessary with improved diagnostics A. Loarte lCRH Interface Review Meeting 10 June 2008 13

  14. JET-Riccardo NF’05 MAST-Counsell Energy release at TQ: Wt.q. (relative to the peak stored energy Wmax) - Wt.q./Wmax < 0.5 (typically 0.2-0.3) for H-mode discharges - Wt.q. 300 MJ (very rare case; e.g., large impurity influx due to uncontrolled ELM) - High beta disruption, VDE cases ; Wt.q.  Wmax VDE A. Loarte lCRH Interface Review Meeting 10 June 2008 14

  15. Expansion of energy load width during thermal quench from steady heat load width ss Loarte IAEA 04 - Expansion of 5-10 for divertor machines ==> 5-10 is assumed - Limiter machine; different between machine ==> 1.5-10 is assumed 1.5-2 for TEXTOR, TFTR  8 for MAST - VDE (limiter TQ but some indication of ==> 3-10 is assumed broadening of 3) A. Loarte lCRH Interface Review Meeting 10 June 2008 15

  16. Time duration of energy deposition on the divertor and first wall Loarte IAEA 2004 Energy deposition time on divertor is longer than the energy loss time from core  1.5-3 ms on divertor target plate is expected in ITER Decay phase of energy deposition is longer than rise phase (factor  2) A. Loarte lCRH Interface Review Meeting 10 June 2008 16

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