Fusion Theory at Auburn University

I am currently a Ph.D. candidate in physics at Auburn University with two co-advisors: Luca Guazzotto and Evdokiya Kostadinova

Despite it being a little unorthodox to have two advisors, I am extremely fortunate to have simultaneous connection to so many areas of plasma theory by being a part of both groups.

My Dissertation Work

My dissertation will largely be about exploring the effect of two-fluid equilibrium flows on (classical) linear tearing mode stability. Much about equilibrium flows and how they effect properties of fusion plasmas is understudied or unknown. By investiagting these effects we can gain better insight into plasma modeling and what happens at higher flow speeds. From an experiental point of view, understanding flows can be a control mechanism or even a predictor for instability.

Two-Fluid Effects on Linear Tearing Mode Stability

In a two-fluid model of a tokamak plasma, equilibrium rotation is tied to “flow surfaces” that are close to, but distinct from, magnetic surfaces. As a result, the equilibrium plasma velocity acquires a component normal to the magnetic surfaces. This normal flow, which varies poloidally, is expected to qualitatively modify the behavior of magnetic-surface-localized instabilities, such as tearing modes. I am working on an analytical investigation in the slab approximation of linear tearing mode stability in the presence of two-fluid equilibrium flow. The poloidal periodicity of the normal flow introduces coupling between sideband poloidal harmonics, and the resistive layer equation gains additional terms dependent on the derivatives of these sidebands. In Fourier space, these equations combine into a single differential equation that is analytically intractable without further simplification. By applying standard order of magnitude estimates within the layer, we reduce the problem to a solvable form and derive analytic expressions for the tearing stability index Δ′ in both the constant-flux and internal kink regimes. Preliminary analysis suggests that the equilibrium flow has a stabilizing effect. These analytical findings are validated against numerical simulations. The model is then applied to flow profiles representative of several tokamak confinement geometries. This work is supported by DE-SC0023061, DE-SC0024547, and DE-SC0014196.