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Concerns on Integration of A Liquid Metal Divertor. Richard Nygren (Sandia). Heat load D/T and He pumping Plumbing/configuration Safety & Maintenance. CLIFF Concept. “flow convertor” modifies flow for divertor. APEX Program - Divertor Integration Subtask. Heat Removal.
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Concerns on Integration of A Liquid Metal Divertor Richard Nygren (Sandia) • Heat load • D/T and He pumping • Plumbing/configuration • Safety & Maintenance CLIFF Concept “flow convertor” modifies flow for divertor APEX Program - Divertor Integration Subtask
Heat Removal • configuration issues • space requirements • conductance for He pumping • modified first wall stream or “separate” divertor flow • flux expansion • incline of liquid surfaces • thermal-hydraulic issues • improving thermal mixing • nozzle design (separate divertor) • B MHD effects • plasma physics issue • He neutral pressure for pumping • Is a droplet divertor feasible? (large lq - “diffuse” scrape-off) ARIES-RS Fusion Power 2171 MW Pa, alpha power 433 MW Pshare,div 10% Pdiv (10% Pa) 43.3 MW divertorinnerouter R-div (m) 4.0 5.0 fx, flux exp. 300% 300% fraction 35% 65% lq, nom (m) 0.002 0.002 q,incline (deg) 75 75 L, lqfx/sinq (m) 0.012 0.012 A=2PRL (m2) 0.31 0.39 frad-div 50% 50% Pave (MW/m2)24.3 36.1
2.0 3.0 4.0 ITER’s divertor curves away from the plasma spreading the heat load. The separatrix angles down (q) and allows room for the inner divertor. q In ARIES-RS, the inner leg of the separatrix is more nearly horizontal and tighter to the inner coils, which means that there is less space for the inner divertor. The free liquid surfaces in a divertor cannot curve away from the plasma. (Deflection from gravity is small. EM forces might be used to redirect flow.) q
2.0 3.0 4.0 Modified FW Flow • Flow Convertor (FC) • natural break-up ?possible? • separate cassette? • some P needed • space & structure • flow issues: 2-D turbulence, turbulence promoters, droplets? • Divertor collector • configuration • pump port location • He conductance • Blanket flow • bypass FC support • Simple case: Extend first wall flows • Use flux expansion in the divertor to reduce the surface heat load • Problem 1: High heat flux • Problem 2: Streams converge at nearly right angles high in the divertor region.
2.0 3.0 4.0 Separate Stream • Divertor • separate cassette • inlet/outlet piping • MHD P, insulator • added space, structure • flow issues: 2-D turbulence, turbulence promoters, droplets • Divertor collector • configuration • He conductance • Blanket flow • bypass divertor, separate collection? With two divertor nozzles, redirecting the inner first wall flow may be difficult due to constraints in space. With a hybrid design, the first wall stream becomes the inner divertor (green). This may be possible with strong in/out asymmetry in power loads. It also mixes blanket and divertor streams.