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Valeryi Sizyuk Ahmed Hassanein School of Nuclear Engineering, Purdue University

The effect of runaway electrons on plasma facing components in ITER device  A serious threat to its success!. Valeryi Sizyuk Ahmed Hassanein School of Nuclear Engineering, Purdue University PFC community meeting, MIT, Boston July 8-10, 2009. Outline. HEIGHTS Upgrade

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Valeryi Sizyuk Ahmed Hassanein School of Nuclear Engineering, Purdue University

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  1. The effect of runaway electrons on plasma facing components in ITER device  A serious threat to its success! Valeryi Sizyuk Ahmed Hassanein School of Nuclear Engineering, Purdue University PFC community meeting, MIT, Boston July 8-10, 2009

  2. Outline • HEIGHTS Upgrade • Modeling of Runaway Electrons • ITER device Geometry and Main Values • Simulation Results • Summary

  3. Energy Deposition (Ions, Plasma, Laser, Electrons) HEIGHTS Simulation Package

  4. Plasma Transient / Instabilities:Plasma Material Interaction KeyConcerns • HEIGHTS major modeling events for surface and structural response to plasma transients: • Edge Localized Modes (ELM’s) • Disruptions • Vertical Displacement Events (VDE’s) • Runaway electrons • Key concerns: • PFC erosion lifetime • PFC structural integrity • Plasma contamination

  5. Runaway Electrons • Normal electrons collide with plasma ions/electrons-limiting their energy • Runaway electrons-are accelerated by toroidal electric field, collisions decrease as E-1.5; runaway process • Existing work: crude model; angle of incidence = magnetic field angle. Our work: rigorous computation of angle, penetration depth, 3-D effects

  6. Detailed Analysis is Needed of Runaway Electrons Energy Deposition and Structural Response Very Serious! Et = 50 MeV B = 5-8 T Time = 10-100 ms Energy Density 50 MJ/m2

  7. Runaway Electrons Impact Angle

  8. Runaway Electrons Incident Angle Distribution energy ratio

  9. Runaway Electron Monte Carlo Energy Deposition Model This includes: • Electron-Electron Scattering • Electron-Nuclear Scattering • Bremsstrahlung • Compton Absorption • Photoabsorption • Auger Relaxation

  10. Model Benchmarking --Very good agreement seen [37] Tabata A. 1994 Atom. Dat. Nuc. Dat. Tab. 56 105 [38] Lockwood G.J., Ruggles L.E., Miller G.H., Halbleib J.A. 1980 Calorimetric measurement of electron energy deposition in extended media – theory vs experiment Report SAND79-0414 (Sandia Laboratories) [39] Nakai Y. 1963 Jap. J. Appl. Phys. 2 743 [40] Spencer L.V. 1959 Energy dissipation by fast electrons Monograph 1 (Natl. Bur. Std.) [42] Morawska-Kaczynska M., Huizenga H. 1992 Phys. Med. Biol. 37 2103

  11. HEIGHTS Benchmarking HEIGHTS Calculation Previous Numerical Simulations (1) Maddaluno G., Maruccia G., Merola M., Rollet S. 2003 J. Nucl. Mater. 313-316 651 (2) Hender T.C., et al. Progress in the ITER Physics Basis 2007 Nucl. Fusion 47 S128 E = 10 MeV B = 8 T  = 1 deg P = 50 MJ/m2 t = 0.1 s

  12. Influence of Energy Ratio Et = 50 MeV B = 8 T Time = 10 ms Energy Density 50 MJ/m2

  13. Idea: Tungsten Layer as Additional Absorber W of 0.1-mm thick W of 0.8-mm thick Et = 50 MeV E= 0.1Et B = 8 T Time = 10 ms Energy Density 50 MJ/m2

  14. Influence of Tungsten Layer Location on Be and Cu Temperature W of 0.8-mm thick W of 0.1-mm thick

  15. Influence of Tungsten Layer Location on Cu Temperature W of 0.8-mm thick W of 0.1-mm thick

  16. Summary and Conclusion • Runaway electron analysis - major model development and HEIGHTS package effort completed • Excellent HEIGHTS/data comparison • Tangential part of particle energy increases angle of incidence • Increased incident angle leads to overheating of deep layers • Serious problem for ITER - melting, danger of interlayer destruction, and damage to coolant channels • A dual (Be/W) structure may be one solution • Design optimization of damage mitigation may be possible • More analysis just accepted for publication in NF (2009)

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