Observation of Edge Instability Limiting the Pedestal Growth in Tokamak Plasmas

• Main Authors: Diallo, A. (Author), Davis, E. (Contributor), Theiler, C. (Contributor), Snyder, P. (Author), Canik, J. (Author), Walk, J. (Contributor), Churchill, M. (Contributor), Delgado-Aparicio, Luis (Author), White, A. (Contributor), Hughes, Jerry W., Jr (Contributor), Greenwald, Martin J. (Contributor), Labombard, Brian (Contributor), Baek, Seung Gyou (Contributor), Golfinopoulos, Theodore (Contributor), Terry, James L. (Contributor), Hubbard, Amanda E. (Contributor), Porkolab, Miklos (Contributor), Reinke, Matthew Logan (Contributor)
• Other Authors: Massachusetts Institute of Technology. Plasma Science and Fusion Center (Contributor)
• Format: Article
• Language: English
• Published: American Physical Society, 2014-08-22T17:02:18Z.
• Subjects: Article
• Online Access: Get fulltext

 With fusion device performance hinging on the edge pedestal pressure, it is imperative to experimentally understand the physical mechanism dictating the pedestal characteristics and to validate and improve pedestal predictive models. This Letter reports direct evidence of density and magnetic fluctuations showing the stiff onset of an edge instability leading to the saturation of the pedestal on the Alcator C-Mod tokamak. Edge stability analyses indicate that the pedestal is unstable to both ballooning mode and kinetic ballooning mode in agreement with observations.