Active Beam Dump Module Design for MFTF-B^a

An actively-cooled dump module design is being developed for use in the MFTF-B long pulse neutral beamlines. The modular approach allows for application of the same design inseveral different areas, such as positive ion dumps, neutral dumps and beamline apertures. The dump modules are required to dissipate up to 1.2 MW of beam power with peak heat fluxes as high as 1500 W/cm² for a lifetime of 50,000 cycles. The modules are constructed from two rows of 1.91 cm O.D. × 0.318 cm wall (0.75 × 0.125 in.) oxygen-free copper tubing, staggered to achieve maximum optical density. The tubes are bent into a “C” shape and connected to large diameter manifolds at each end. Thermal analysis of conduction in the tube wall has been performed to predict inner wall heat flux and tube wall temperature profiles. The results have been used both as an input to critical heat flux assessment as well as an input to NASTRAN stress analysis. The NASTRAN analysis has shown that tube deflections will be within allowable limits and that the design life will be ≅ 100,000 cycles.