Toroidal mode number estimation of the edge-localized modes using the KSTAR 3-D electron cyclotron emission imaging system

J Lee; G S Yun; J E Lee; M Kim; M J Choi; W Lee; H K Park; C W Domier; N C Luhmann Jr; S A Sabbagh; Y S Park; S G Lee; J G Bak

doi:10.1063/1.4883180

Toroidal mode number estimation of the edge-localized modes using the KSTAR 3-D electron cyclotron emission imaging system

Rev Sci Instrum. 2014 Jun;85(6):063505. doi: 10.1063/1.4883180.

Authors

J Lee¹, G S Yun¹, J E Lee¹, M Kim¹, M J Choi¹, W Lee¹, H K Park², C W Domier³, N C Luhmann Jr³, S A Sabbagh⁴, Y S Park⁴, S G Lee⁵, J G Bak⁵

Affiliations

¹ Pohang University of Science and Technology, Pohang 790-784, South Korea.
² Ulsan National Institute of Science and Technology, Ulsan 689-798, South Korea.
³ University of California at Davis, Davis, California 95616, USA.
⁴ Columbia University, New York, New York 10027, USA.
⁵ National Fusion Research Institute, Daejeon 305-333, South Korea.

PMID: 24985817
DOI: 10.1063/1.4883180

Abstract

A new and more accurate technique is presented for determining the toroidal mode number n of edge-localized modes (ELMs) using two independent electron cyclotron emission imaging (ECEI) systems in the Korea Superconducting Tokamak Advanced Research (KSTAR) device. The technique involves the measurement of the poloidal spacing between adjacent ELM filaments, and of the pitch angle α* of filaments at the plasma outboard midplane. Equilibrium reconstruction verifies that α* is nearly constant and thus well-defined at the midplane edge. Estimates of n obtained using two ECEI systems agree well with n measured by the conventional technique employing an array of Mirnov coils.