29th Annual Student Research Conference
Quantifying non-axisymmetric perturbations at tokamak plasma edge
Joseph M. Milliano
Dr. Carlos Paz-Soldan (General Atomics/DIII-D) and Dr. Vayujeet Gokhale, Faculty Mentors
Tokamak plasmas, while largely axisymmetric, exhibit non-axisymmetric displacements due to both internal instabilities and intentionally applied 3D magnetic fields. Measuring these displacements can identify non- axisymmetric sensitivities to various parameters and benchmark existing plasma response models. We measure the spatial shift of temperature, density, and rotation profiles as n = 2 3D fields are applied by the DIII-D upper and lower in-vessel coils. The currents are quickly inverted, shifting the toroidal phase of the applied fields by 180◦. These quick polarity inversions allow us to extract information about the non-axisymmetric properties of the plasma, while keeping the overall axisymmetric properties unchanged. Using a variety of toroidally separated high-resolution kinetic profile diagnostics, we infer the magnitude of these displacements at various toroidal angles. The absolute magnitude of the displacements are compared against different applied n = 2 field pitches and different underlying axisymmetric equilibrium conditions, such as plasma pressure and collisionality.
Keywords: Plasma, Physics, Data Analysis, Nuclear, Fusion, Perturbation, non-axisymmetric
Topic(s):Physics
Presentation Type: Oral Paper
Session: -1
Location: MG 1096
Time: 1:00