A snowflake divertor: a possible solution to the power exhaust problem for tokamaks

• Published in: Plasma physics and controlled fusion Vol. 54; no. 12; pp. 124050 - 124057
• Main Authors: Ryutov, D D, Cohen, R H, Rognlien, T D, Umansky, M V
• Format: Journal Article
• Language: English
• Published: United States IOP Publishing 01.12.2012; IOP Science
• Subjects: 70 PLASMA PHYSICS AND FUSION; GENERAL STUDIES OF NUCLEAR REACTORS
• ISSN: 0741-3335; 1361-6587
• DOI: 10.1088/0741-3335/54/12/124050

This paper summarizes recent progress in the theory of a snowflake divertor, a possible path to reduce both steady-state and intermittent heat loads on the divertor plates to an acceptable level. The most important feature of a SF divertor is the presence of a large zone of a very weak poloidal magnetic field around the poloidal field (PF) null. Qualitative explanation of a variety of new features characteristic of a SF divertor is provided based on simple scaling relations. The main part of the paper is focused on the concept of spreading of the heat flux by curvature-driven convection near the PF null. References to experimental results from the NSTX and TCV tokamaks are provided.