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Title: Investigation of dynamics of ELM crashes and their mitigation techniques

The accurate prediction of H-mode pedestal dynamics is critical for planning experiments in existing tokamaks and in the design of future tokamaks such as ITER and DEMO. The main objective of the proposed research is to advance the understanding of the physics of H-mode pedestal. Through advances in coupled kinetic-MHD simulations, a new model for H-mode pedestal and ELM crashes as well as an improved model for the bootstrap current will be developed. ELMmitigation techniques will also be investigated. The proposed research will help design efficient confinement scenarios and reduce transient heat loads on the divertor and plasma facing components. During the last two years, the principal investigator (PI) of this proposal actively participated in physics studies related to the DOE Joint Research Targets. These studies include the modeling of divertor heat load in the DIII-D, Alcator C-Mod, and NSTX tokamaks in 2010, and the modeling of H-mode pedestal structure in the DIII-D tokamak in 2011. It is proposed that this close collaboration with experimentalists from major US tokamaks continue during the next funding period. Verification and validation will be a strong component of the proposed research. During the course of the project, advances will be made in the followingmore » areas; Dynamics of the H-mode pedestal buildup and recovery after ELM crashes – The effects of neutral fueling, particle and thermal pinches will be explored; Dynamics of ELM crashes in realistic tokamak geometries – Heat loads associated with ELM crashes will be validated against experimental measurements. An improved model for ELM crashes will be developed; ELM mitigation – The effect of resonant magnetic perturbations on ELMs stability and their evolution will be investigated; Development of a new bootstrap current model – A reduced model for will be developed through careful verification of existing models for bootstrap current against first-principle kinetic neoclassical simulations. The primary focus here will be on plasma regimes where the existing reduced models deviate from each other, such as high-beta and low aspect ratio plasmas; and Results will be verified against analytical models and simulation results from other codes. Simulation results will be compared with diagnostic experimental data such as Thomson measurements (HRTC) or flux measurements if available. We have arrangements with experimentalists from DIII-D and JET to use diagnostic edge data for this validation. In summary, we propose to study the H-mode pedestal buildup, the stability and evolution of ELMs using a model that will account for dynamically evolving neoclassical sources.« less
  1. Tech-X Corporation, Boulder, CO (United States)
Publication Date:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Technical Report
Research Org:
Tech-X Corporation, Boulder, CO (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
42 ENGINEERING; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY Thermonuclear fusion; plasma physics; tokamaks; edge localized modes; H-mode pedestal; stability