A New Divertor System Using Fusible Metal Pebbles

• Published in: Plasma and Fusion Research 2019/07/24, Vol.14, pp.3405050-3405050
• Main Authors: OHGO, Takeru, GOTO, Takuya, MIYAZAWA, Junichi
• Format: Article
• Language: English
• Subjects: conceptual design; divertor; fusible metal; liquid metal; pebble divertor
• ISSN: 1880-6821; 1880-6821
• DOI: 10.1585/pfr.14.3405050

A fusible metal pebble divertor system named the REVOLVER-D2 is newly proposed here, based on the molten tin jet divertor REVOLVER-D and the pebble divertor concepts. In the REVOLVER-D2, solid tin pebble flows are used as the divertor target. Molten tin pools receive the falling tin pebbles to mitigate the impact of the heavy metal shower. All pebbles are melted in the molten tin pool and recycled into the tin pebbles again. The solid tin pebbles are formed inside the vacuum vessel by the shot tower method using silicone oil pools. This concept enables simultaneous achievement of a high heat load tolerance and a high evacuation efficiency, while mitigating the MHD effects. A high heat load can be removed by the pebble flow if the pebble size is large enough and the velocity is fast enough as with the molten tin jet. Although the charge up of pebbles affects the pebble motion due to the Lorentz force and the Coulomb force, the Lorentz force is negligible if the injection velocity is fast enough. For example, center-to-center pebble distance due to the Coulomb force will be ∼4 mm in the case of the injection velocity of 10 m/s if the molten tin pool is placed 2 m under the point where pebbles enter the ergodic layer.