1. Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
2. National Fusion Research Institute, Daejeon 34133, South Korea
3. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
4. Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
5. Pohang University of Science and Technology, Pohang 37673, South Korea