C. Hansen
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View article: HE2159-0551: A very metal-poor peculiar low-Ba giant – a candidate from the LMS-1/Wukong
HE2159-0551: A very metal-poor peculiar low-Ba giant – a candidate from the LMS-1/Wukong Open
Aims . We present a comprehensive spectroscopic and kinematic analysis of the very metal-poor ([Fe/H] = −2.60 ± 0.20 dex) giant star HE2159-0551. By investigating the star’s chemodynamic characteristics, we seek to address its formation, e…
View article: Systematic analysis of magnetic equilibrium reconstruction with eddy currents on LTX-<i>β</i>
Systematic analysis of magnetic equilibrium reconstruction with eddy currents on LTX-<i>β</i> Open
Magnetic equilibrium reconstruction in the Lithium Tokamak Experiment-Beta (LTX- β ) is complicated by strong eddy currents and toroidal asymmetries arising from its segmented, close-fitting conducting shell. In the earlier experiment LTX,…
View article: HE2159-0551: a very metal-poor peculiar low Ba giant -- a candidate from the LMS-1/Wukong
HE2159-0551: a very metal-poor peculiar low Ba giant -- a candidate from the LMS-1/Wukong Open
We present a comprehensive spectroscopic and kinematic analysis of the very metal-poor ([Fe/H] = -2.60 $\pm$ 0.20 dex) giant star HE2159-0551. By investigating the star's chemodynamic characteristics, we seek to address its formation, evol…
View article: Spatiotemporal forecasting of the edge localized modes in tokamak plasmas using neural networks
Spatiotemporal forecasting of the edge localized modes in tokamak plasmas using neural networks Open
Artificial intelligence techniques have been increasingly adopted by the plasma and fusion science to address problems like plasma reconstruction, surrogate modeling, and tokamak/stellarator optimization. A key focus in sustained fusion re…
View article: Counterintuitive Particle Confinement in a Helical Force-Free Plasma
Counterintuitive Particle Confinement in a Helical Force-Free Plasma Open
The force-free magnetic field solution formed in a high-aspect ratio cylinder is a non-axisymmetric (m=1), closed magnetic structure that can be produced in laboratory experiments. Force-free equilibria can have strong field gradients that…
View article: Doubling fusion power with volumetric optimization in magnetic confinement fusion devices
Doubling fusion power with volumetric optimization in magnetic confinement fusion devices Open
A technique, volumetric power optimization, is presented for enhancing the power output of magnetic confinement fusion devices. Applied to a tokamak, this approach involves shifting the burning plasma region to a larger plasma volume while…
View article: Simulations of saturated MHD activity in the HBT-EP tokamak
Simulations of saturated MHD activity in the HBT-EP tokamak Open
The NIMROD code is used to perform simulations of MHD activity in the HBT-EP tokamak, including the effect of a resistive wall. Linear simulations are conducted to scan current and pressure profiles to establish self-consistent baseline eq…
View article: Electromagnetic System Conceptual Design for a Negative Triangularity Tokamak
Electromagnetic System Conceptual Design for a Negative Triangularity Tokamak Open
Negative triangularity (NT) tokamak configurations have several key benefits including sufficient core confinement, improved power handling, and reduced edge pressure gradients that allow for edge-localized mode (ELM) free operation. We pr…
View article: Error field predictability and consequences for ITER
Error field predictability and consequences for ITER Open
ITER coil tolerances are re-evaluated using the modern understanding of coupling to least-stable plasma modes and an updated center-line-traced model of ITER’s coil windings. This reassessment finds the tolerances to be conservative throug…
View article: Reconstruction of plasma equilibrium and eddy current induced error fields in the Lithium Tokamak eXperiment-β (Final Report)
Reconstruction of plasma equilibrium and eddy current induced error fields in the Lithium Tokamak eXperiment-β (Final Report) Open
This is the final report for the DOE award DE-SC0019239, titled “Reconstruction of plasma equilibrium and eddy current induced error fields in the Lithium Tokamak eXperiment-” for the period July 1, 2018 – July 2, 2023. This award support…
View article: MANTA: a negative-triangularity NASEM-compliant fusion pilot plant
MANTA: a negative-triangularity NASEM-compliant fusion pilot plant Open
The MANTA (Modular Adjustable Negative Triangularity ARC-class) design study investigated how negative-triangularity (NT) may be leveraged in a compact, fusion pilot plant (FPP) to take a ‘power-handling first’ approach. The result is a pu…
View article: Low latency optical-based mode tracking with machine learning deployed on FPGAs on a tokamak
Low latency optical-based mode tracking with machine learning deployed on FPGAs on a tokamak Open
Active feedback control in magnetic confinement fusion devices is desirable to mitigate plasma instabilities and enable robust operation. Optical high-speed cameras provide a powerful, non-invasive diagnostic and can be suitable for these …
View article: MANTA: A Negative-Triangularity NASEM-Compliant Fusion Pilot Plant
MANTA: A Negative-Triangularity NASEM-Compliant Fusion Pilot Plant Open
The MANTA (Modular Adjustable Negative Triangularity ARC-class) design study investigated how negative-triangularity (NT) may be leveraged in a compact, fusion pilot plant (FPP) to take a ``power-handling first" approach. The result is a p…
View article: Validation of Simulation Models for Wall-Connected Scrape off Layer Currents during MHD Activity in the HBT-EP Tokamak (Final Report)
Validation of Simulation Models for Wall-Connected Scrape off Layer Currents during MHD Activity in the HBT-EP Tokamak (Final Report) Open
This is the final report for the DOE award DE-SC0021325, titled “Validation of Simulation Models for Wall-Connected Scrape off Layer Currents during MHD Activity in the HBT-EP Tokamak” for the period September 1, 2020 – May 31, 2023. This …
View article: Assessment of vertical stability for negative triangularity pilot plants
Assessment of vertical stability for negative triangularity pilot plants Open
Negative triangularity (NT) tokamak configurations may be more susceptible to magneto-hydrodynamic instability, posing challenges for recent reactor designs centered around their favorable properties, such as improved confinement and opera…
View article: Boundary condition effects on runaway electron mitigation coil modeling for the SPARC and DIII-D tokamaks
Boundary condition effects on runaway electron mitigation coil modeling for the SPARC and DIII-D tokamaks Open
Extended-MHD modeling of planned Runaway Electron Mitigation Coils (REMC) for SPARC and DIII-D is performed with the NIMROD code. A coil has been designed for each machine, with the two differing in shape and location, but both having n = …
View article: Doubling Fusion Power with Volumetric Optimization in Magnetic Confinement Fusion Devices
Doubling Fusion Power with Volumetric Optimization in Magnetic Confinement Fusion Devices Open
A technique, volumetric power optimization, is presented for enhancing the power output of magnetic confinement fusion devices. Applied to a tokamak, this approach involves shifting the burning plasma region to a larger plasma volume while…
View article: Extending the trapping theorem to provide local stability guarantees for quadratically nonlinear models
Extending the trapping theorem to provide local stability guarantees for quadratically nonlinear models Open
The Navier Stokes equations (NSEs) are partial differential equations (PDEs) to describe the nonlinear convective motion of fluids and they are computationally expensive to simulate because of their high nonlinearity and variables being fu…
View article: Investigating the role of edge neutrals in exciting tearing mode activity and achieving flat temperature profiles in LTX-β
Investigating the role of edge neutrals in exciting tearing mode activity and achieving flat temperature profiles in LTX-β Open
We present observations, numerical simulations, and analysis from experiments in the Lithium Tokamak Experiment-Beta (LTX- β ) in which the electron temperature profile ( T e ( r )) shifts from flat to peaked and a tearing mode is also des…
View article: Estimates of global recycling coefficients for LTX-<i>β</i> discharges
Estimates of global recycling coefficients for LTX-<i>β</i> discharges Open
We report the first observation of global recycling coefficient R near 0.5 in the Lithium Tokamak eXperiment-β (LTX-β), significantly below the minimum R previously reported in other devices. In a series of experiments with varied Li wall …
View article: Assessment of vertical stability for negative triangularity pilot plants
Assessment of vertical stability for negative triangularity pilot plants Open
Negative triangularity (NT) tokamak configurations may be more susceptible to magneto-hydrodynamic instability, posing challenges for recent reactor designs centered around their favorable properties, such as improved confinement and opera…
View article: Low latency optical-based mode tracking with machine learning deployed on FPGAs on a tokamak
Low latency optical-based mode tracking with machine learning deployed on FPGAs on a tokamak Open
Active feedback control in magnetic confinement fusion devices is desirable to mitigate plasma instabilities and enable robust operation. Optical high-speed cameras provide a powerful, non-invasive diagnostic and can be suitable for these …
View article: TokaMaker: An open-source time-dependent Grad-Shafranov tool for the design and modeling of axisymmetric fusion devices
TokaMaker: An open-source time-dependent Grad-Shafranov tool for the design and modeling of axisymmetric fusion devices Open
In this paper, we present a new static and time-dependent MagnetoHydroDynamic (MHD) equilibrium code, TokaMaker, for axisymmetric configurations of magnetized plasmas, based on the well-known Grad-Shafranov equation. This code utilizes fin…
View article: Design of passive and structural conductors for tokamaks using thin-wall eddy current modeling
Design of passive and structural conductors for tokamaks using thin-wall eddy current modeling Open
A new three-dimensional electromagnetic modeling tool ( ThinCurr ) has been developed using the existing PSI-Tet finite-element code in support of conducting structure design work for both the SPARC and DIII-D tokamaks. Within this framewo…
View article: Design of Passive and Structural Conductors for Tokamaks Using Thin-Wall Eddy Current Modeling
Design of Passive and Structural Conductors for Tokamaks Using Thin-Wall Eddy Current Modeling Open
A new three-dimensional electromagnetic modeling tool ThinCurr has been developed using the existing PSI-Tet finite-element code in support of conducting structure design work for both the SPARC and DIII-D tokamaks. Within this framework a…
View article: Optimization of the equilibrium magnetic sensor set for the SPARC tokamak
Optimization of the equilibrium magnetic sensor set for the SPARC tokamak Open
Accurate reconstruction of the plasma equilibrium is imperative for successful operation of the SPARC tokamak. In order to assess the expected reconstruction accuracy throughout the duration of design-point discharges, the EFIT equilibrium…