A5040716996- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Plasma Diagnostics and Applications
- Particle accelerators and beam dynamics
- Solar and Space Plasma Dynamics
- Laser-Plasma Interactions and Diagnostics
- Astronomical Observations and Instrumentation
- Nuclear reactor physics and engineering
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Memory Processes and Influences
- Laser-induced spectroscopy and plasma
- Advanced Materials Characterization Techniques
- Atomic and Molecular Physics
- Nuclear Engineering Thermal-Hydraulics
- Advanced Thermodynamic Systems and Engines
- X-ray Spectroscopy and Fluorescence Analysis
- Nuclear physics research studies
- Gas Dynamics and Kinetic Theory
- Advanced Numerical Analysis Techniques
- Visual and Cognitive Learning Processes
- Physics of Superconductivity and Magnetism
- Spacecraft and Cryogenic Technologies
Auburn University
2017-2024
Southwest Research Institute
2024
Energy Center of Wisconsin
2023
Max Planck Institute for Plasma Physics
2018-2019
Max Planck Society
2018-2019
University of Wisconsin–Madison
2003-2017
Princeton Plasma Physics Laboratory
2013-2017
Columbia University
2017
Princeton University
2016
Arkansas Tech University
2011
It has been predicted for over a decade that low-recycling plasma-facing components in fusion devices would allow high edge temperatures and flat or nearly temperature profiles. In recent experiments with lithium wall coatings the Lithium Tokamak Experiment (LTX), hot ($>200\text{ }\text{ }\mathrm{eV}$) electron profiles have measured following termination of external fueling. Reduced recycling was demonstrated by retention $\ensuremath{\sim}60%$ injected hydrogen walls discharge. Electron...
The Wendelstein 7-X (W7-X) optimized stellarator fusion experiment, which went into operation in 2015, has been operating since 2017 with an un-cooled modular graphite divertor. This allowed first divertor physics studies to be performed at pulse energies up 80 MJ, as opposed 4 MJ the phase, where five inboard limiters were installed instead of a This, and number other upgrades device capabilities, extension regimes higher plasma density, heating power, performance overall, e.g. setting new...
Stellarator configurations with reactor relevant energetic particle losses are constructed by simultaneously optimizing for quasisymmetry and an analytically derived metric ( $\unicode[STIX]{x1D6E4}_{c}$ ), which attempts to align contours of the second adiabatic invariant, $J_{\Vert }$ magnetic surfaces. Results show that this optimization scheme it is possible generate quasihelically symmetric equilibria on scale ARIES-CS completely eliminate all collisionless alpha within normalized...
Abstract This research investigates the temporal evolution of toroidal plasma current in Wendelstein 7-X (W7-X) stellarator under different heating, fueling, and drive scenarios. The THRIFT code has been modernized its predictions have compared against experimentally measured currents W7-X. Good agreement is found with respect to characteristic timescale between simulated currents. total bootstrap under-predicted owing applicability BOOTSJ model for collisionalities question. Edge...
Transport characteristics and predicted confinement are shown for the Infinity Two fusion pilot plant baseline plasma physics design, a high field stellarator concept developed using modern optimization techniques. predictions made fidelity nonlinear gyrokinetic turbulence simulations along with drift kinetic neoclassical simulations. A pellet fueled scenario is proposed that enables supporting an edge density gradient to substantially reduce ion temperature turbulence. Trapped electron mode...
The selection, design, and optimization of a suitable blanket configuration for an advanced high-field stellarator concept is seen as key feasibility issue has been incorporated vital necessary part the Infinity Two Fusion Pilot Plant (FPP) physics basis. focus this work was to identify baseline which can be rapidly deployed while also maintaining flexibility opportunities higher performing concepts later in development. Results from analysis indicate that gas-cooled solid breeder designs...
The magneto-hydrodynamic equilibrium and stability properties of the Infinity Two Fusion Pilot Plant baseline plasma physics design are presented. configuration is a four field period, aspect ratio A = 10 quasi-isodynamic stellarator optimized for excellent confinement at elevated density high magnetic B 9 T. Magnetic surfaces exist in core vacuum retain good surface integrity from to an operational β 1.6%, volume average pressures, corresponding 800 MW Deuterium-Tritium fusion operation....
We provide an assessment of the Infinity Two Fusion Pilot Plant (FPP) baseline plasma physics design. is a four-field period, aspect ratio A = 10, quasi-isodynamic stellarator with improved confinement appealing to max-J approach, elevated density and high magnetic fields (⟨ B ⟩ 9 T). At envisioned operating point [800 MW deuterium-tritium (DT) fusion], configuration has robust surfaces based on magnetohydrodynamic (MHD) equilibrium calculations stable both local global MHD instabilities....
In this work, we present a detailed assessment of fusion-born alpha-particle confinement, their wall loads, and stability Alfvén eigenmodes driven by these energetic particles in the Infinity Two Fusion Pilot Plant Baseline Plasma Design, 4-field-period quasiisodynamic stellarator to operate deuterium-tritium fusion conditions. Using Monte-Carlo codes SIMPLE, ASCOT5, KORC-T, study collisionless collisional dynamics guiding-center full-orbit alpha-particles core plasma. We find that energy...
The first-ever successful operation of a tokamak with large area (40% the total plasma surface area) liquid lithium wall has been achieved in Lithium Tokamak eXperiment (LTX). These results were obtained new, electron beam-based evaporation system, which can deposit coating on limiting LTX five-minute period. Preliminary analyses diamagnetic and other data for discharges operated indicate that confinement times increased by 10× compared to helium-dispersed solid coatings. Ohmic energy fresh...
High edge electron temperatures (200 eV or greater) have been measured at the wall-limited plasma boundary in Lithium Tokamak Experiment (LTX). Flat temperature profiles are a long-predicted consequence of low recycling conditions. Plasma density outer scrape-off layer is very low, 2–3 × 1017 m−3, consistent with metallic lithium boundary. Despite high temperature, core impurity content low. Zeff estimated to be ∼1.2, modest contribution (<0.1) from lithium. Experiments transient. Gas...
A new optimized quasihelically symmetric configuration is described that has the desir-able properties of improved energetic particle confinement, reduced turbulent transportby 3D shaping, and non-resonant divertor capabilities. The presented in thispaper explicitly for quasihelical symmetry, confinement,neoclassical stability near axis. Post optimization, configurationwas evaluated its performance with regard to transport, idealmagnetohydrodynamic (MHD) at various values plasma pressure,...
Nine stellarator configurations, three quasiaxisymmetric, quasihelically symmetric and non-quasisymmetric are scaled to ARIES-CS size analyzed for energetic particle content. The best performing configurations with regard confinement also perform the on neoclassical {\Gamma}c metric, which attempts align contours of second adiabatic invariant flux surfaces. Quasisymmetric that simultaneously well quasisymmetry have overall confinement, collisional losses under 3%, approaching performance...
This paper describes an initial description of the resilient divertor properties quasi-symmetric (QS) stellarators using HSX (Helically Symmetric eXperiment) configuration as a test-case. Divertors in high-performance QS will need to be changes plasma that arise due evolution pressure profiles and bootstrap currents for design. Resiliency is tested by examining strike point patterns from field line following, which configurational changes. A low variation with high corresponds resiliency....
The 3D effects on divertor heat loads have been investigated for performance-optimized island configurations at Wendelstein 7-X with modeling and IR camera measurements. A new high mirror configuration optimized more stable operation due to reduced bootstrap currents a even load distribution between the main targets has first time numerically experimentally. Transport calculations EMC3-EIRENE show strong dependence of flux distributions details geometry. measurements confirm predictions...
Abstract Wendelstein 7-X (W7-X) (Greifswald, Germany) is an advanced stellarator, which uses the modular coil concept to realize a magnetic configuration optimized for fusion-relevant plasma properties. The magnet system of machine allows variation rotational transform (iota) at boundary. In latest W7-X operational phase dedicated scan has been performed varying between configurations with iota = 5/4 and 5/5 This paper presents overview experiments main results respect confinement stability....
The Lithium Tokamak eXperiment is a small, low aspect ratio tokamak [Majeski et al., Nucl. Fusion 49, 055014 (2009)], which fitted with stainless steel-clad copper liner, conformal to the last closed flux surface. liner can be heated 350 °C. Several gas fueling systems, including supersonic injection and molecular cluster injection, have been studied produce efficiencies up 35%. Discharges are strongly affected by wall conditioning. without lithium coatings limited plasma currents of order...
Abstract The optimization of helically symmetric experiment (HSX) for reduced microinstability has been achieved by examining a large set configurations within neighborhood the standard operating configuration. This entailed generating database more than 10 6 magnetic-field HSX varying currents in external coils. Using volume-averaged metrics and gyrokinetic simulations, this helped to identify that can be used regulate trapped-electron-mode stability HSX. is also found correlate...
Axisymmetric equilibrium reconstruction using magnetohydrodynamic solutions to the Grad?Shafranov equation has long been an important tool for interpreting tokamak experiments. This paper describes recent results in non-axisymmetric (three-dimensional) of nominally axisymmetric plasmas (tokamaks and reversed field pinches (RFPs)), fully (stellarators). Results from applying V3FIT code CTH HSX stellarator plasmas, RFX-mod RFP DIII-D are presented.
The first fast ion experiments in Wendelstein 7-X were performed 2018. They are one of the steps demonstrating optimised confinement stellarator. ions produced with a neutral beam injection (NBI) system and detected infrared cameras (IR), loss detector (FILD), charge exchange spectroscopy (FIDA), post-mortem analysis plasma facing components. distribution function at wall is being modelled ASCOT suite codes. calculate ionisation injected neutrals consecutive slowing down process ions....