DocumentCode :
2539819
Title :
Engineering design of cryocondensation pumps for the DIII-D radiative divertor program
Author :
Bozek, A.S. ; Baxi, G.B. ; Bene, J. V Del ; Laughon, G.J. ; Reis, E.E. ; Shatoff, H.D. ; Smith, J.P.
Author_Institution :
Gen. Atomics, San Diego, CA, USA
Volume :
2
fYear :
1995
fDate :
30 Sep-5 Oct 1995
Firstpage :
898
Abstract :
A new double-null, slotted divertor configuration will be installed for the DIII-D Radiative Divertor Program at General Atomics in late 1996. Four cryocondensation pumps, three new and one existing, will be part of this new divertor. The purpose of the pumps is to provide plasma density control and to limit the impurities entering the plasma core by providing pumping at each divertor strike point. The three new pumps are based on the design of the existing pump, installed in 1992 as part of the Advanced Divertor Program. The pump continues to operate successfully. The toroidally continuous pumps vary in lengths from approximately 7 to 12 m depending upon their locations within the vessel. Each pump is independently operated and offers on average 0.7 m 2 of liquid helium-cooled pumping surface. The tubular pumping surface is surrounded concentrically by nitrogen shields and a particle shield of larger diameters. The nitrogen-cooled shields limit the heat flux on the helium surface. The particle shield limits energetic particles from impacting the helium and nitrogen cooled surfaces, preventing the condensed gases on the pump, primarily water, from being released. The new pumps require geometry modifications to the original design. Therefore, extensive modal and dynamic analyses were performed to determine the behavior of these pumps and their helium and nitrogen feed lines during disruption events. Thermal and fluid analyses were also performed to characterize the helium two-phase flow regime in the pumps and their feedlines. A flow testing program was completed to test the change in geometry of the pump feed lines with respect to helium flow stability. The results were compared to the helium thermal and fluid analyses to verify predicted flow regimes and flow stability
Keywords :
Tokamak devices; cryopumping; fusion reactor design; fusion reactor instrumentation; fusion reactors; plasma density; plasma impurities; DIII-D radiative divertor program; He flow stability; condensed gases; cryocondensation pumps; disruption events; divertor strike point; double-null slotted divertor configuration; dynamic analyses; energetic particles; fluid analyses; impurities; liquid helium-cooled pumping surface; modal analyses; nitrogen shields; nitrogen-cooled shields; particle shield; plasma core; plasma density control; pump feed lines; thermal analyses; toroidally continuous pumps; tubular pumping surface; Atomic measurements; Design engineering; Feeds; Geometry; Helium; Nitrogen; Performance analysis; Plasma density; Pumps; Testing;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Fusion Engineering, 1995. SOFE '95. Seeking a New Energy Era., 16th IEEE/NPSS Symposium
Conference_Location :
Champaign, IL
Print_ISBN :
0-7803-2969-4
Type :
conf
DOI :
10.1109/FUSION.1995.534369
Filename :
534369
Link To Document :
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