He-cooled Divertor Development in the EU: The Helium Jet cooled Divertor HEMJ

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1 He-cooled Divertor Development in the EU: The Helium Jet cooled Divertor HEMJ Presented by Thomas Ihli * Contributors: Divertor Group at, Germany and Efremov Institute, Russia ARIES Meeting General Atomics, San Diego February 24-25, 2005 *, currently exchange visitor to UCSD & The ARIES Team 1

2 Introduction: Divertor Requirements Divertor X-point Target plate target length [m] Divertor with Target Plates heat flux [MW/m²] DEMO Divertor main requirements: Heat load up to at least 10 MW/m² & strike point movements Withstand erosive particle flux for several years (low sputtering rate) He-cooling, high He-pressure 100 bars & vacuum leak tightness 2

3 EU Tungsten Divertor: General Design W Armor W Alloy Cap He cooling Structure? heat transfer enhancement Ferritic steel (ODS) or W Alloy / Densimet W-Armor: + High Melting Point + High Heat Conductivity + low Sputtering Rate + activation accaptable - need of low Impurity of W in Plasma (due to high atomic number of W) 3

4 Evolution of Heat Transfer Design HEM P W HEM S HEM J 1300 C 1300 C 1300 C pin array slot array jet array back-up reference simple fabrication max. heat flux 4

5 COOLING TECHNOLOGY: Jet Impingement Cooling technology applied in the fields of: Aircraft Engines Gas Turbines Burners DEMO Divertor HOT Jet Impingement 5

6 HEMJ Cooling Finger: Design & Materials He W Armor (W) Cap (W Alloy) Transition Piece STEEL Cartridge (Steel) He 600 C He 700 C Temp C (TS) Armor Tile ~2500 C (ELMs, disrupt.) Disr.) ~700 C (DBTT) W alloy (e.g. WL10) (RCT) 1300 C Cap Thimble ~600 C (DBTT) He 700 C 600 C Ferritic Steel (ODS) ~700 C Bulk 300 C (DBTT) 6

7 High reliability, low waste during fabrication Construction Kit Principle: Small Units advantageous for R&D progress Small Units can be tested before assembling 9-Finger Unit Stripe-Unit Target Plate Divertor Cassette Test, Assembly Test, Assembly Test, Assembly 7

8 Details of 9-Finger module Steel-plates and cooling fingers 9-finger-module W-section, 600 to 2000 C Collector section He, Steel: 600 to 700 C He He Manifold section He, Steel: 600 to 700 C (Welding: Laser, E-Beam, diffusion welding or HIP) 8

9 R&D on fabrication technologies: high temperature W-joint Second joint First joint 12 W W 20 mm 4 mm 4 mm 1 mm Upper W layer with castellation (10x10 mm) 15 MW/m cycles OK defect after add. 50 cycles at 16 MW/m 2 EFREMOV under contract 9

10 R&D on fabrication technologies: high temperature curved W-joint Brazing successful, survived up to 100 temperature cycles at 14 MW/m2 EFREMOV under contract 10

11 W-Cap Steel Joint (Efremov Inst.) W-Cap Steel-Tube Joint MOCKUP Cross-section of lock-area Cap W Cast copper layer Pins W Leak detected after 2nd thermal cycle Transition piece steel 11

12 R&D on fabrication technologies: W-steel joint Finger mockup (without armour tile) after casting (left) and after posttesting examination (right). 100 thermocycles (p in =10 MPa) ok Main elements for W-Steel joint with new (conic) lock EFREMOV under contract 12

13 Layout example for Multiple-He-Jet-Cooled Divertor Finger Unit W Multiple Jet Cartridge center hole; D = 1 mm a = 18 mm W Alloy D = 15 mm jet-to-wall spacing H = 1.2 mm Steel 24 holes; D = 0.6 mm 13

14 CFD-Results for layout example Flow Velocities Temperatures Temp. [ C] Ma max = 0.13 a = 1770 m/s Veloc. [m/s] 230 T max 1675 C T max 1152 C 0 IRS B.C.: Results: IMF III Helium, 10 MPa, T_in 630 C, heat load: 10 MW/m²: max. Temperature in W-Cap: 1152 C (< 1300 C) Pressure drop: 0.14 MPa Mass flow per finger: 6.8 g/s 14

15 Minimal He mass flow for different jet hole diameters Recrystallisation T max thimble [ C] J1a J1d J1e Potenziell (J1e) Potenziell (J1a) Potenziell (J1d) HEM J heat flux: 10 MW/m² J1a: D = 0.6 mm J1d: D = 0.7 mm J1e: D = 0.85 mm mass flow [g/s] 15

16 Armor Cap Joint Improved Finger Design Stress intensity for bonded armor, 10 MW/m², 10 MPa Stress intensities depending on cap interface treatment and heat flux: ANSYS FE Connection Stress Intensity Bonded 377 MPa No separation 228 MPa 3Sm at 1100 C ~ 460 MPa at 850 C ~ 580 MPa 16

17 Efremov GPF2: Scheme & Mock-ups Helium Pressure Vessels Heat Exchanger Water Caps (brass) Pressure Tank Compressor Mock up Cartridges (steel) Heat Exchanger 17

18 Pressure drop [kpa] PL FUSION Pressure drop GPF 2 RESULTS ( p) for 2004 brass mock-ups Pressure drop, kpa Reasonable layout: G = 7 g/s, dp = 100 kpa S1c24 N3 HEMJ MJ1e N1 D = 0.85 MJ1e N2 MJ1e N3 MJ1a N3 HEMS 24 x 0.3 mm HEMJ D = 0.6 MJ1a N Mass flow [g/s] MJ1a N5 mfr, g/s

19 GPF 2 RESULTS for 2004 brass mock-ups Heat flux [MW/m 2 ] Power, MW/m 2 S1c24 N3 MJ1e N1 MJ1e N2 MJ1e N3 MJ1a N3 MJ1a N4 MJ1a N5 Power HEMJ D = 0.85 CFD Calculation GPF tests (CuCrZr) HEMJ D = 0.6 HEMS 24 x 0.3 mm Mass flow [g/s] mfr, g/s

20 HEMJ Layout for OB target (PPCS Model B) Zone 1 & 2 Zone 3 Zone 4 OB 24 fingers zone length in parallel 432 mm 38 fingers zone length in parallel 684 mm 78 fingers zone length in parallel 1404 mm HEXAGONAL TILE mass flow: 7.9 g/s dp: 103 kpa (76%) heat flux: MW/m² holes: 24 x 0.71 mm, 1 x 1.47 mm SQUARE TILE mass flow: 5.4 g/s dp: 55 kpa (69%) heat flux: 7 MW/m² holes: 24 x 0.7 mm, 1 x 1.47 mm SQUARE TILE mass flow: 2.46 g/s dp: 37 kpa (60%) heat flux: 3.2 MW/m² holes: 12 x 0.7 mm, 1 x 1.47 mm 1 OB 20

21 Reactors Objectives: He-cooled Divertor on the way to ITER & DEMO DEMO ITER 2020 Cassette, TDM Targets Materials, Design, Joining Big Parts Development Finger Units 9-Finger-Units Stripe-Units Small Parts Development 21