J.W. Berkery
A5055228983- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Nuclear reactor physics and engineering
- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Nuclear Engineering Thermal-Hydraulics
- earthquake and tectonic studies
- Atomic and Molecular Physics
- Particle Accelerators and Free-Electron Lasers
- Atomic and Subatomic Physics Research
- Risk and Safety Analysis
- Electrohydrodynamics and Fluid Dynamics
- Astro and Planetary Science
- Electromagnetic Launch and Propulsion Technology
- Gyrotron and Vacuum Electronics Research
- Distributed and Parallel Computing Systems
- Geological formations and processes
- Nuclear Physics and Applications
- Fault Detection and Control Systems
- Earthquake Detection and Analysis
Princeton Plasma Physics Laboratory
2011-2025
Princeton University
2001-2024
Columbia University
2011-2022
Applied Mathematics (United States)
2007-2020
Los Alamos National Laboratory
2009
Kyoto Institute of Technology
2009
Abstract The objectives of NSTX-U research are to reinforce the advantages STs while addressing challenges. To extend confinement physics low- A , high beta plasmas lower collisionality levels, understanding transport mechanisms that set performance and pedestal profiles is being advanced through gyrokinetic simulations, reduced model development, comparison NSTX experiment, as well improved simulation RF heating. develop stable non-inductive scenarios needed for steady-state operation,...
Disruption prediction and avoidance is a critical need for next-step tokamaks, such as ITER. Event Characterization Forecasting (DECAF) research fully automates analysis of tokamak data to determine chains events that lead disruptions forecast their evolution allowing sufficient time mitigation or complete the disruption. event related local rotating global magnetohydrodynamic (MHD) modes vertical instability are examined with warnings issued many off-normal physics events, including density...
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...
Stabilizing modes that limit plasma beta and reduce their deleterious effect on rotation are key goals for the efficient operation of a fusion reactor. Passive stabilization active control global kink/ballooning resistive wall (RWMs) have been demonstrated NSTX research is now advancing towards understanding physics reliably maintaining high confident extrapolation to ITER component test facility based spherical torus. Active n = 1 experiments with an expanded sensor set, combined low levels...
The resistive wall mode (RWM) instability in high-beta tokamaks is stabilized by energy dissipation mechanisms that depend on plasma rotation and kinetic effects. Kinetic modification of ideal stability calculated with the “MISK” code [B. Hu et al., Phys. Plasmas 12, 057301 (2005)] outlined. For an advanced scenario ITER [R. Aymar Nucl. Fusion 41, 1301 (2001)] plasma, present calculation finds alpha particles are required for RWM at presently expected levels rotation. stabilization theory...
Experimental observation of resistive wall mode (RWM) instability in the National Spherical Torus Experiment (NSTX) at plasma rotation levels intermediate to ion precession drift and bounce frequencies suggests that low critical threshold models are insufficient. Kinetic modifications ideal stability criterion yield a more complex relationship between RWM stability. Good agreement is found an experimental marginal point calculated with kinetic effects included, by MISK code. By...
The low-aspect ratio, low magnetic field and wide range of plasma beta NSTX plasmas provide new insight into the origins effects errors. An extensive array sensors has been used to analyse error fields, measure error-field amplification detect resistive wall modes (RWMs) in real time. measured normalized threshold for onset locked shows a linear scaling with density, weak inverse dependence on toroidal positive shear. These results extrapolate favourable ITER. For these low-beta locked-mode...
Key plasma physics and real-time control elements needed for robustly stable operation of high fusion power discharges in ITER have been demonstrated recent research worldwide.Recent analysis has identified the current density profile as main drive disruptive instabilities simulating ITER's baseline scenario with low external torque.Ongoing development model-based active magnetohydrodynamic is improving stability multiple scenarios.Significant advances made toward physicsbased prediction...
One of the biggest challenges to achieve goal producing fusion energy in tokamak devices is necessity avoiding disruptions plasma current due instabilities. The Disruption Event Characterization and Forecasting (DECAF) framework has been developed this purpose, integrating physics models many causal events that can lead a disruption. Two different machine learning approaches are proposed improve ideal magnetohydrodynamic (MHD) no-wall limit component kinetic stability model included DECAF....
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>...
Abstract The SMall Aspect Ratio Tokamak (SMART) under commissioning at the University of Seville, Spain, aims to explore confinement properties and possible advantages in for compact/spherical tokamaks operating negative vs. positive triangularity. This work explores benefits auxiliary heating through Neutral Beam Injection (NBI) SMART scenarios beyond initial Ohmic phase operations, support device’s mission. Expected values electron ion temperature achievable with NBI are first predicted...
Research on the National Spherical Torus Experiment, NSTX, targets physics understanding needed for extrapolation to a steady-state ST Fusion Nuclear Science Facility, pilot plant, or DEMO. The unique operational space is leveraged test theories next-step tokamak operation, including ITER. Present research also examines implications coming device upgrade, NSTX-U. An energy confinement time, τE, scaling unified varied wall conditions exhibits strong improvement of BTτE with decreased electron...
The National Spherical Torus Experiment (NSTX) has undergone a major upgrade, and the NSTX Upgrade (NSTX-U) Project was completed in summer of 2015.NSTX-U first plasma subsequently achieved, diagnostic control systems have been commissioned, H-mode accessed, magnetic error fields identified mitigated, physics research campaign carried out.During ten run weeks operation, NSTX-U surpassed record pulse-durations toroidal (TF), high-performance ~1 MA plasmas comparable to best sustained near...
A technique, volumetric power optimization, is presented for enhancing the output of magnetic confinement fusion devices. Applied to a tokamak, this approach involves shifting burning plasma region larger volume while introducing minimal perturbations boundary shape. This edge perturbation—squareness—is analogous pinching and stretching boundary. Stability calculations confirm that alteration compatible with maintaining stability. optimization method optimizing could improve performance...
Validating the calculations of kinetic resistive wall mode (RWM) stability is important for confidently predicting RWM stable operating regions in ITER and other high performance tokamaks disruption avoidance. Benchmarking Magnetohydrodynamic Resistive Spectrum—Kinetic (MARS-K) [Y. Liu et al., Phys. Plasmas 15, 112503 (2008)], Modification to Ideal Stability by Kinetic effects (MISK) [B. Hu 12, 057301 (2005)], Perturbed Equilibrium Nonambipolar Transport (PENT) [N. Logan 20, 122507 (2013)]...
Active measurements of the plasma stability in tokamak plasmas reveal importance kinetic resonances for resistive wall mode stability. The rotation dependence magnetic response to externally applied quasistatic $n=1$ fields clearly shows signatures an interaction between and precession bounce motions trapped thermal ions, as predicted by a perturbative model including effects. identification stabilization mechanism is essential step towards quantitative predictions prospects ``passive''...
The mission of the National Spherical Torus Experiment (NSTX) is demonstration physics basis required to extrapolate next steps for spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based (ST-CTF), and support ITER. Key issues are transport, steady state high β operation. To better understand electron new high- k scattering diagnostic was used extensively investigate gyro-scale fluctuations with varying temperature gradient scale length. Results from n = 3...
This paper presents a calculation of neoclassical toroidal viscous torque independent large-aspect-ratio expansions across kinetic regimes. The Perturbed Equilibrium Nonambipolar Transport (PENT) code was developed for this purpose, and is compared to previous combined regime models as well specific limits drift δf guiding center code. It shown that retaining general expressions, without circular or other orbit approximations, can be important at experimentally relevant aspect ratio shaping....
Kinetic modification of ideal stability theory from stabilizing resonances mode-particle interaction has had success in explaining resistive wall mode (RWM) limits tokamaks. With the goal real-time forecasting, a reduced kinetic model been implemented new Disruption Event Characterization and Forecasting (DECAF) code, which written to analyze disruptions The incorporates parameterized models for on β, ratio plasma pressure magnetic pressure, are shown be good agreement with DCON code...
Along with an expanded evaluation of the equilibrium operating space Korea Superconducting Tokamak Advanced Research, KSTAR, experimental equilibria most recent plasma discharges were reconstructed using EFIT code. In near-circular plasmas created in 2009, reached a stored energy 54 kJ maximum current 0.34 MA. Highly shaped near double-null configuration 2010 achieved H-mode clear edge localized mode (ELM) activity, and transiently up to 257 kJ, elongation 1.96 normalized beta 1.3. The 0.7...
The impact of collisionless, energy-independent, and energy-dependent collisionality models on the kinetic stability resistive wall mode is examined for high pressure plasmas in National Spherical Torus Experiment. Future devices will have decreased collisionality, which previous predict to be universally destabilizing. In contrast, theory reduced ion-ion collisions are shown lead a significant increase when plasma rotation frequency stabilizing resonance with ion precession drift frequency....
Abstract DIII-D physics research addresses critical challenges for the operation of ITER and next generation fusion energy devices. This is done through a focus on innovations to provide solutions high performance long pulse operation, coupled with fundamental plasma understanding model validation, drive scenario development by integrating core boundary plasmas. Substantial increases in off-axis current efficiency from an innovative top launch system EC power, pressure broadening Alfven...
The National Spherical Torus Experiment Upgrade (NSTX-U) will advance the physics basis required for achieving steady-state, high-beta, and high-confinement conditions in a tokamak by accessing high toroidal fields (1 T) plasma currents (1.0–2.0 MA) low aspect ratio geometry (A = 1.6–1.8) with flexible auxiliary heating systems (12 MW NBI, 6 HHFW). This paper describes progress development of L- H-mode discharge scenarios commissioning operational tools first ten weeks operation that enable...