Characteristics of pre-ELM structures during ELM control experiment on JET with n  =  2 magnetic perturbations. (29th July 2016)

• Record Type: Journal Article
• Authors: Gao, Y.; Rack, M.; Liang, Y.; Sieglin, B.; Denner, P.
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 56:Number 9(2016:Sep.)
• Publication Date: 2016-07-29
• Subjects: pre-ELM structures -- heat flux -- magnetic perturbations -- infra-red thermography; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/0029-5515/56/9/092011
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: Radially propagating pre-ELM (edge localized mode) structures in the heat flux profile on the outer divertor have been observed both with and without magnetic perturbations on Joint European Torus. Recently pre-ELM structures over 80% of the ELM cycle are observed. The effects of n = 2 fields on pre-ELM structures are presented and analysed in detail. Redistribution of the inter-ELM heat load with the appearances of pre-ELM structures suggest that a wider energy wetted area could be achieved by the application of n = 2 fields. The influences of q 95 and gas puffing position on the change of pre-ELM structures are studied. Pre-ELM structures are normally long lived (several milliseconds) and appear consecutively with n = 2 fields, but do not necessarily lead to an ELM crash. The experimental observations suggest that the changed magnetic topology might be a possible explanation for the propagating structures.