A5076307875- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Nuclear reactor physics and engineering
- Anomaly Detection Techniques and Applications
- Nuclear Physics and Applications
- Magnetic Field Sensors Techniques
- Integrated Circuits and Semiconductor Failure Analysis
- Semiconductor materials and devices
- Electron and X-Ray Spectroscopy Techniques
- Solar and Space Plasma Dynamics
- Particle Accelerators and Free-Electron Lasers
- Advanced Data Storage Technologies
- Network Security and Intrusion Detection
- Advanced X-ray Imaging Techniques
- Non-Destructive Testing Techniques
- Nuclear Materials and Properties
- Force Microscopy Techniques and Applications
- Plasma and Flow Control in Aerodynamics
- Nuclear Engineering Thermal-Hydraulics
- Atomic and Subatomic Physics Research
Fusion Academy
2019-2025
James J. Peters VA Medical Center
2024-2025
Fusion (United States)
2019-2024
Plasma Technology (United States)
2019-2024
Massachusetts Institute of Technology
2019-2024
GlobalFoundries (United States)
2013-2024
Boston Fusion (United States)
2023-2024
Mental Illness Research, Education and Clinical Centers
2024
Chalmers University of Technology
2023
ITER
2019-2021
The SPARC tokamak is a critical next step towards commercial fusion energy. designed as high-field ( $B_0 = 12.2$ T), compact $R_0 1.85$ m, $a 0.57$ m), superconducting, D-T with the goal of producing gain $Q>2$ from magnetically confined plasma for first time. Currently under design, will continue path Alcator series tokamaks, utilizing new magnets based on rare earth barium copper oxide high-temperature superconductors to achieve high performance in device. achievable conservative...
Abstract The SPARC tokamak project, currently in engineering design, aims to achieve breakeven and burning plasma conditions a compact device, thanks new developments high-temperature superconductor technology. With magnetic field of 12.2 T on axis 8.7 MA current, is predicted produce 140 MW fusion power with gain Q ≈ 11, providing ample margin respect its mission > 2. All systems are being designed this landmark discharge, thus enabling the study physics operations reactor relevant pave...
SPARC is being designed to operate with a normalized beta of $\beta _N=1.0$ , density $n_G=0.37$ and safety factor $q_{95}\approx 3.4$ providing comfortable margin their respective disruption limits. Further, low poloidal _p=0.19$ at the $q=2$ surface reduces drive for neoclassical tearing modes, which together frozen-in classically stable current profile might allow access robustly tearing-free operating space. Although inherent stability expected reduce frequency disruptions, loading...
Abstract A series of experiments have been executed at JET to assess the efficacy newly installed shattered pellet injection (SPI) system in mitigating effects disruptions. Issues, important for ITER disruption mitigation system, such as thermal load mitigation, avoidance runaway electron (RE) formation, radiation asymmetries during quench electromagnetic control and RE energy dissipation addressed over a large parameter range. The efficiency has examined various SPI strategies. paper...
Abstract In this paper, we present a new deep-learning disruption-prediction algorithm based on important findings from explorative data analysis which effectively allows knowledge transfer existing devices to ones, thereby predicting disruptions using very limited disruption the devices. The analysis, conducted via unsupervised clustering techniques confirms that time-sequence are much better separators of disruptive and non-disruptive behavior than instantaneous plasma-state data, with...
Abstract Precise values for radiated energy in tokamak disruption experiments are needed to validate mitigation techniques burning plasma tokamaks like ITER and SPARC. Control room analysis of power ( P rad ) on JET assumes axisymmetry, since fitting 3D radiation structures with limited bolometry coverage is an under-determined problem. In mitigated disruptions, toroidally asymmetric 3D, due fast-growing MHD modes localized impurity sources. To address this problem, Emis3D adopts a physics...
Abstract The pre-thermal quench (pre-TQ) dynamics of a pure deuterium ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi mathvariant="normal">D</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:math> ) shattered pellet injection (SPI) into <mml:mn>3</mml:mn> <mml:mstyle scriptlevel="0"/> <mml:mi>MA</mml:mi> / <mml:mn>7</mml:mn> <mml:mi>MJ</mml:mi> JET H-mode plasma is studied via 3D non-linear MHD modelling with the JOREK code....
Abstract A database has been developed to study the evolution, nonlinear effects on equilibria, and disruptivity of locked quasi-stationary modes with poloidal toroidal mode numbers m = 2 n 1 at DIII-D. The analysis 22500 discharges shows that more than 18% disruptions are due or rotating precursors (not including born modes). parameter formulated by plasma internal inductance l i divided safety factor 95% flux, q 95 , is found exhibit predictive capability over whether a will cause...
Locked modes are known to be one of the major causes disruptions, but physical mechanisms by which locking leads disruptions not well understood. Here we analyze evolution temperature profile in presence multiple coexisting locked during partial and full thermal quenches. Partial quenches often observed an initial, distinct stage quench. Near onset quenches, island O-points align with each other on midplane, their widths sufficient overlap other, as indicated Chirikov parameter. Energy...
The potential formation of multi-mega-ampere beams relativistic "runaway" electrons (REs) during sudden terminations tokamak plasmas poses a significant challenge to the tokamak's development as fusion energy source. Here, we use state-of-the-art modeling disruption magnetohydrodynamics coupled with self-consistent evolution RE generation and transport show that non-axisymmetric in-vessel coil will passively prevent beam disruptions in SPARC tokamak, compact, high-field, high-current device...
The operation of a 3D coil--passively driven by the current quench loop voltage--for deconfinement runaway electrons is modeled for disruption scenarios in SPARC and DIII-D tokamaks. Nonlinear MHD modeling carried out with NIMROD code including time-dependent magnetic field boundary conditions to simulate effect coil. Further some cases uses ASCOT5 calculate advection diffusion coefficients based on NIMROD-calculated fields, DREAM compute evolution presence these transport coefficients....
Abstract Runaway electrons (REs) created during tokamak disruptions pose a threat to the reliable operation of future larger machines. Experiments using shattered pellet injection (SPI) have been carried out at JET investigate ways prevent their generation or suppress them if avoidance is not sufficient. Avoidance possible SPI contains sufficiently low fraction high-Z material, it fired early in advance disruption prone runaway generation. These results are consistent with previous similar...
Abstract The ability to identify underlying disruption precursors is key avoidance. In this paper, we present an integrated deep learning (DL) based model that combines prediction with the identification of several like rotating modes, locked H-to-L back transitions and radiative collapses. first part our study demonstrates DL-based unstable event identifier trained on 160 manually labeled DIII-D shots can achieve, average, 84% rate various frequent events (like H-L transition, mode,...
Abstract Nonlinear 3D MHD simulations of shattered-pellet injection (SPI) in JET show prototypical SPI-driven disruptions using the M3D-C1 and NIMROD extended-MHD codes. Initially, radiation-driven thermal quenches are accelerated by activity as pellet crosses rational surfaces, leading to a radiation spike, global stochasticization magnetic field, complete quench. Eventually, current quenches, preceded spike seen Ohmic heating becomes equal radiative cooling. The results qualitatively...
We have developed a method for imaging the temperature-frequency dependence of dynamics nanostructured polymer films with spatial resolution. This provides images dielectric compositional contrast well decoupled from topography. Using frequency-modulation electrostatic-force-microscopy, we probe local frequency-dependent (0.1–100 Hz) response through measurement amplitude and phase force gradient in to an oscillating applied electric field. When is imaged at fixed frequency, it reveals...
Abstract Disruption mitigation remains a critical, unresolved challenge for ITER. To aid in addressing this challenge, shattered pellet injection (SPI) system was installed on JET and experiments conducted at range of thermal energy fractions stored energies excess 7 MJ. The primary goals these were to investigate the efficacy SPI ability plasma assimilate multiple pellets. Single injections produced saturation total radiated ( W rad ) with increasing injected neon content, suggesting...
Abstract Experimental trends in thermal plasma partial recombination resulting from massive <?CDATA ${{\text{D}}_2}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mtext>D</mml:mtext> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:math> injection into high-Z (Ar) containing runaway electron (RE) plateaus DIII-D and JET are studied for the purpose of achieving sufficiently low density ( ${n_{\text{e}}} \approx {10^{18}}{{\text{m}}^{...
Two primary systems planned for disruption mitigation in the SPARC tokamak, massive gas injection (MGI), and runaway electron coil (REMC), are modeled with 3D MHD code NIMROD. MGI is four configurations, each of 6-valve 4-valve configurations considered predicted to produce a high radiation fraction (&gt;95%) low toroidal peaking factor [&lt;1.5 during thermal quench (TQ)]. The MGI-induced TQ also conjunction REMC two different scenarios: one which assumed be closed-circuit, another...
Despite research identifying cognitive deficits that are specific to individuals with major depressive disorder and a history of suicidal behavior (SB), no known study has investigated remediation (CR) for suicide risk reduction in this patient population. The aim was evaluate feasibility, acceptability outcomes brief-format (10-week), group-based CR program adapted from the evidence-based intervention NEAR (Neuropsychological Educational Approach Cognitive Remediation) veterans SB. Nine US...
Previous investigations on JET suggest half or less of plasma stored thermal energy Wth is radiated (frad,th≲0.5) using either massive gas injection (MGI) shattered pellet (SPI) disruption mitigation. We investigate whether the apparent incomplete frad,th explained by radiation peaking near plume. High toroidal throughout pre-thermal quench found in argon–deuterium MGI JET, with typically &gt;3× higher injector than toroidally distant. Previously unexplained bolometry measurements...
In order to inform core performance projections and divertor design, the baseline SPARC tokamak plasma discharge is evaluated for its expected H-mode access, pedestal pressure edge-localized mode (ELM) characteristics. A clear window access predicted full field DT plasmas, with available 25 MW of design auxiliary power. Additional alpha heating likely needed sustainment. Pressure predictions in developed are surveyed using EPED model. The projected would be limited dominantly by peeling...
One of the most pressing challenges facing fusion community is adequately mitigating or, even better, avoiding disruptions tokamak plasmas. However, before this can be done, must first predicted with sufficient warning time to actuate a response. The established field survival analysis provides convenient statistical framework for time-to-event (i.e. time-to-disruption) studies. This paper demonstrates integration an existing disruption prediction machine learning algorithm Kaplan–Meier...
Next generation high performance (HP) tokamaks risk damage from unmitigated disruptions at current and power. Achieving reliable disruption prediction for a device's HP operation based on its low (LP) data is key to success. In this letter, through explorative analysis dedicated numerical experiments multiple existing tokamaks, we demonstrate how the operational regimes of can affect power trained predictor. First, our results suggest data-driven predictors abundant LP discharges work poorly...
Shattered pellet injection (SPI) has been adopted as the baseline disruption mitigation system for ITER, radiative payload penetration into DIII-D plasmas from SPI is superior to those using massive gas (MGI) method. Because of substantial differences in energy content ITER plasma and present experiments, reliable 3D MHD modeling, benchmarked against experiments needed project plasmas. In support these needs, depth fragment was investigated by injecting two discharges with vastly different...
Abstract 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 SPARC and DIII-D tokamaks. Within this framework a 3D model was created tokamaks thin-wall limit. This includes accurate details vacuum vessel other structural elements with realistic material resistivities. leveraged to passive runaway electron mitigation coil (REMC), studying effect various...