A5027521278- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Model Reduction and Neural Networks
- Physics of Superconductivity and Magnetism
- earthquake and tectonic studies
- Stellar, planetary, and galactic studies
- Gas Dynamics and Kinetic Theory
- High-Energy Particle Collisions Research
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Combustion and Detonation Processes
- Geophysics and Gravity Measurements
- Adaptive optics and wavefront sensing
- Nuclear reactor physics and engineering
- Fluid Dynamics and Turbulent Flows
- Advanced Thermodynamics and Statistical Mechanics
- Astronomical Observations and Instrumentation
- Particle accelerators and beam dynamics
- High-pressure geophysics and materials
- Nuclear Engineering Thermal-Hydraulics
Princeton University
2023-2025
University of Maryland, College Park
2023-2025
We apply a continuation method to recently optimized stellarator equilibria with excellent quasi-axisymmetry generate new wide range of rotational transform profiles. Using these equilibria, we investigate how the affects fast-particle confinement, maximum coil–plasma distance, growth rate in linear gyrokinetic ion-temperature gradient simulations and ion heat flux corresponding nonlinear simulations. find values two-term quasi-symmetry error comparable or lower than those similar...
Abstract A theoretical model is presented that for the first time matches experimental measurements of pedestal width-height Diallo scaling in low-aspect-ratio high- β tokamak NSTX. Combining linear gyrokinetics with self-consistent equilibrium variation, kinetic-ballooning, rather than ideal-ballooning plasma instability, shown to limit achievable confinement spherical pedestals. Simulations are used find novel Gyrokinetic Critical Pedestal constraint, which determines steepest pressure...
We present new stellarator equilibria that have been optimized for reduced turbulent transport using nonlinear gyrokinetic simulations within the optimization loop. The routine involves coupling pseudo-spectral GPU-native code GX with equilibrium and DESC . Since allows fast simulations, we directly optimize heat fluxes. To handle noisy flux traces returned by these employ simultaneous perturbation stochastic approximation (SPSA) method only uses two objective function evaluations a simple...
We use a new gyrokinetic threshold model to predict bifurcation in tokamak pedestal width-height scalings that depends strongly on plasma shaping and aspect-ratio. The arises from the first second stability properties of kinetic-ballooning-modes yields wide narrow branches, expanding space accessible widths heights. branch offers potential for edge-localized-mode-free pedestals with high core pressure. For negative triangularity, low-aspect-ratio configurations are predicted give steeper...
Abstract A gyrokinetic threshold model for pedestal width–height scaling prediction is applied to multiple devices. shaping and aspect ratio scan performed on National Spherical Torus Experiment (NSTX) equilibria, finding <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:mi>ped</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.92</mml:mn> <mml:msup> <mml:mi>A</mml:mi>...
Quasisymmetry (QS), a hidden symmetry of the magnetic field strength, is known to support nested flux surfaces and provide superior particle confinement in stellarators. In this work, we study ideal magnetohydrodynamic (MHD) equilibrium stability high-beta plasma large-aspect-ratio stellarator. particular, show that lowest-order description near-axisymmetric vastly simplifies problem three-dimensional quasisymmetric MHD equilibria, which can be reduced standard elliptic Grad–Shafranov...
GX is a code designed to solve the nonlinear gyrokinetic system for low-frequency turbulence in magnetized plasmas, particularly tokamaks and stellarators. In GX, our primary motivation target fast solver that can be used fusion reactor design optimization along with wide-ranging physics exploration. This has led several algorithm decisions, specifically chosen prioritize time solution. First, we have discretization pseudospectral entire phase space, including Laguerre–Hermite formulation of...
High-power-density tokamaks offer a potential solution to design cost-effective fusion devices. One way achieve high power density is operate at $\beta$ value (the ratio of thermal magnetic pressure), i.e. $\beta \sim 1$ . However, state may be unstable various pressure- and current-driven instabilities or have unfavourable microstability properties. To explore these possibilities, we generate equilibria investigate their stability. First, demonstrate the generation high- with computer code...
A large number of magnetohydrodynamic (MHD) equilibrium calculations are often required for uncertainty quantification, optimization, and real-time diagnostic information, making MHD codes vital to the field plasma physics. In this paper, we explore a method solving Grad–Shafranov equation by using physics-informed neural networks (PINNs). For PINNs, optimize directly minimizing residual partial differential as loss function. We show that PINNs can accurately effectively solve with several...
We demonstrate a fast adjoint-based method to optimise tokamak and stellarator equilibria against pressure-driven instability known as the infinite- $n$ ideal ballooning mode. present three finite- $\beta$ (the ratio of thermal magnetic pressure) equilibria: one equilibrium two that are unstable Using self-adjoint property magnetohydrodynamics, we construct technique rapidly calculate change in eigenvalue, measure instability. SIMSOPT optimisation framework, then implement our adjoint...
To build an economically viable stellarator, it is essential to find a configuration that satisfies set of favorable properties achieve efficient steady-state nuclear fusion. One such property omnigenity, which ensures confinement trapped particles. After creating omnigenous equilibrium, one must also ensure reduced transport resulting from kinetic and magnetohydrodynamic (MHD) instabilities. This study introduces leverages the GPU-accelerated DESC optimization suite, used design stable...
We present a framework for analysing plasma flow in rotating mirror. By making series of physical assumptions, we reduce the magnetohydrodynamic (MHD) equations three-dimensional cylindrical system to one-dimensional shallow, cuboidal channel within transverse magnetic field, similar Hartmann ducts. then solve both numerically and analytically range values number calculate dependence speed on thickness insulating end cap. observe that mean overshoots decelerates before achieving steady-state...
A theoretical model is presented that for the first time matches experimental measurements of pedestal width-height Diallo scaling in low-aspect-ratio high-$\beta$ tokamak NSTX. Combining linear gyrokinetics with self-consistent equilibrium variation, kinetic-ballooning, rather than ideal-ballooning plasma instability, shown to limit achievable confinement spherical pedestals. Simulations are used find novel Gyrokinetic Critical Pedestal constraint, which determines steepest pressure profile...
We present new stellarator equilibria that have been optimized for reduced turbulent transport using nonlinear gyrokinetic simulations within the optimization loop. The routine involves coupling pseudo-spectral GPU-native code GX with equilibrium and DESC. Since allows fast simulations, we directly optimize heat fluxes. To handle noisy flux traces returned by these employ simultaneous perturbation stochastic approximation (SPSA) method only uses two objective function evaluations a simple...
We apply a continuation method to recently optimized stellarator equilibria with excellent quasi-axisymmetry (QA) generate new wide range of rotational transform profiles. Using these equilibria, we investigate how the affects fast-particle confinement, maximum coil-plasma distance, growth rate in linear gyrokinetic ion-temperature gradient (ITG) simulations, and ion heat flux corresponding nonlinear simulations. find values two-term quasisymmetry error comparable or lower than similar...
A large number of magnetohydrodynamic (MHD) equilibrium calculations are often required for uncertainty quantification, optimization, and real-time diagnostic information, making MHD codes vital to the field plasma physics. In this paper, we explore a method solving Grad-Shafranov equation by using Physics-Informed Neural Networks (PINNs). For PINNs, optimize neural networks directly minimizing residual PDE as loss function. We show that PINNs can accurately effectively solve with several...
We use a new gyrokinetic threshold model to predict bifurcation in tokamak pedestal width-height scalings that depends strongly on plasma shaping and aspect-ratio. The arises from the first second stability properties of kinetic-ballooning-modes yields wide narrow branches, expanding space accessible widths heights. branch offers potential for edge-localized-mode-free pedestals with high core pressure. For negative triangularity, low-aspect-ratio configurations are predicted give steeper...