Characterization of a turbulence bifurcation underlying L-mode confinement transitions on Alcator C-Mod

Empirical energy confinement scalings play a crucial role in the design of tokamak fusion reactors, measuring how quickly energy is transported by turbulence from the fusion-producing core to conduction loss at the edge. Unfortunately, experiments often exhibit discontinuous changes in scaling behavior as the plasma parameters are varied, termed confinement transitions. Navigating these transitions requires an understanding of the physical origin and limits of confinement scalings, and is crucial for retiring the physics risk of extrapolating empirical results to future reactors. This thesis explores the connection between two universally observed transitions in tokamak transport: the Linear to Saturated Ohmic Confinement (LOC/SOC) transition and the concomitant intrinsic rotation reversal. Analysis and modeling of rotation reversal hysteresis experiments show that a single turbulent bifurcation underlies both transitions on Alcator C-Mod.

Name thesis:degree_name

Doctoral

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Nuclear Science and Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2020

Author dc:creator

• Cao, Norman Ming-Chen.

Advisor dc:contributor.advisor

• John E. Rice.

• Nuclear Science and Engineering.

Statement dc:rights

• MIT theses may be protected by copyright. Please reuse MIT thesis content according to the MIT Libraries Permissions Policy, which is available through the URL provided.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1721.1/127313

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/127313