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Abstract
In order to gain basic information on the magnetically guided liquid metal Li waterfall type blanket concept for ICF reactors and liquid metal Li free surface flow for FMIT type accelerator target, an experimental study was conducted by using LINAK (NaK: 50l, Ar: 0–0.3 MPa) device. A 45 mm O.D. and 25 mm I.D. annular free jet of NaK, which flowed downwards coaxially through a superconducting magnet (2.7T max, B=0.38 T at the nozzle exit), was formed in vacuum chamber and at the nozzle exit where magnetic flux density Bwas divergent. The experiment covered ranges of U=0.5–2.5 m/s and B=0–0.38 T at the nozzle exit. Photographic and VTR observations were made on the behavior of outer surface of annular flow. The results are summarized as follows.
(1) When Bu=0 T, the downward flow was rather convergent due to the surface tension. (2) By applying B, the flow became divergent like a cone shell and more stable. The divergent half angle increased with intensifying B. (3) The experimental results on the flow divergence agreed fairly well with the numerical analysis which took into account the MHD force, the surface tension and the gravitational force. (4) No growth of outer surface disturbance occurred within an attained maximum divergent half angle of 8° or less. The results are considered to be encouraging for applying to ICF blanket and FMIT type target.