A5053864250- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Particle accelerators and beam dynamics
- Nuclear Physics and Applications
- Nuclear reactor physics and engineering
- Atomic and Molecular Physics
- X-ray Spectroscopy and Fluorescence Analysis
- Laser-induced spectroscopy and plasma
- Nuclear Materials and Properties
- Solar and Space Plasma Dynamics
- Electromagnetic Launch and Propulsion Technology
- Metal and Thin Film Mechanics
- Advanced Fiber Optic Sensors
- Nuclear Engineering Thermal-Hydraulics
- High-pressure geophysics and materials
- Particle Accelerators and Free-Electron Lasers
- Combustion and Detonation Processes
- Semiconductor materials and devices
- Magneto-Optical Properties and Applications
- Radiation Detection and Scintillator Technologies
- Atomic and Subatomic Physics Research
Fusion Academy
2008-2024
Oak Ridge National Laboratory
2016-2024
Boston Fusion (United States)
2021-2024
Royal Military Academy
2020
Culham Science Centre
2014-2018
Princeton Plasma Physics Laboratory
2009-2018
Plasma Technology (United States)
2007-2017
Fusion (United States)
2007-2017
University of York
2014-2017
Max Planck Institute for Plasma Physics
2015-2016
An improved energy confinement regime, I-mode, is studied in Alcator C-Mod, a compact high-field divertor tokamak using ion cyclotron range of frequencies (ICRFs) auxiliary heating. I-mode features an edge transport barrier without accompanying particle barrier, leading to several performance benefits. H-mode obtained core impurity accumulation, resulting reduced radiation with high-Z metal wall and ICRF has stationary temperature pedestal localized modes typically absent, while plasma...
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...
High-resolution charge-exchange recombination spectroscopic measurements of B5+ ions have enabled the first spatially resolved calculations radial electric field (Er) in Alcator C-Mod pedestal region [E. S. Marmar, Fusion Sci. Technol. 51, 261 (2006)]. These observations offer new challenges for theory and simulation provide important comparisons with other devices. Qualitatively, structure observed on is similar to that tokamaks. However, narrow high-confinement mode (H-mode) Er well widths...
The behaviour of tungsten in the core hybrid scenario plasmas JET with ITER-like wall is analysed and modelled a combination neoclassical gyrokinetic codes. In these discharges, good confinement conditions can be maintained only for first 2?3?s high power phase. Later W accumulation regularly observed, often accompanied by onset magneto-hydrodynamical activity, particular tearing modes (NTMs), both which have detrimental effects on global energy confinement. dynamics process examined, taking...
The object of this review is to summarize the achievements research on Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994) and Marmar, Fusion Sci. Technol. 51, 261 (2007)] place that in context quest for practical fusion energy. a compact, high-field tokamak, whose unique design operating parameters have produced wealth new important results since it began operation 1993, contributing data extends tests critical physical models into parameter ranges regimes. Using only...
The unique capabilities of the SPARC tokamak mean that it has potential to contribute significantly science and plasma physics, motivating further collaboration broader data access beyond CFS MIT teams. is a compact, high-field currently under construction predicted achieve burning conditions once in operation. experimental advance understanding many aspects including but not limited confinement stability at high field density, disruption boundary physics heat flux management power...
The use of high resolution x-ray crystal spectrometers to diagnose fusion plasmas has been limited by the poor spatial localization associated with chord integrated measurements. Taking advantage a new imaging spectrometer concept [M. Bitter et al., Rev. Sci. Instrum. 75, 3660 (2004)], and improvements in detector technology [Ch. Broennimann J. Synchrotron Radiat. 13, 120 (2006)], spatially resolving built installed on Alcator C-Mod tokamak. This instrument utilizes spherically bent quartz...
Experiments in Alcator C-Mod (Enhanced D-alpha) EDA H-modes with extrinsic impurity seeding (N2, Ne, and Ar) have demonstrated a direct correlation between plasma energy confinement edge power flow, achieving values of H98 ≥ 1 for flows only marginally exceeding the scaled access to H-mode these conditions. For lower Z (N2 Ne), plasmas high are obtained radiative fraction 85% or larger reduction peak heat flux at divertor by more than factor 5 compared similar attached The thus achieved meet...
Intrinsic rotation has been observed in $I$-mode plasmas from the $C$-Mod tokamak, and is found to be similar that $H$ mode, both its edge origin scaling with global pressure. Since have $\ensuremath{\nabla}T$, but completely different $\ensuremath{\nabla}n$, it may concluded drive of intrinsic $\ensuremath{\nabla}T$ rather than $\ensuremath{\nabla}P$. Evidence suggests connection between gradients residual stress, a for conversion free energy macroscopic flow calculated.
We report extended studies of the I-mode regime [Whyte et al., Nucl. Fusion 50, 105005 (2010)] obtained in Alcator C-Mod tokamak [Marmar Sci. Technol. 51(3), 3261 (2007)]. This regime, usually accessed with unfavorable ion B × ∇B drift, features an edge thermal transport barrier without a strong particle barrier. Steady I-modes have now been favorable by using specific plasma shapes, as well drift over wider range shapes and parameters. With power thresholds are close to standard scaling for...
Recent developments in theory-based modelling of core heavy impurity transport are presented, and shown to be necessary for quantitative description present experiments JET ASDEX Upgrade. The treatment impurities is complicated by their large mass charge, which result a strong response plasma rotation or any small background electrostatic field the plasma, such as that generated anisotropic external heating. These forces lead poloidal asymmetries density, have recently been added numerical...
The MIT Plasma Science and Fusion Center collaborators are proposing a high-performance Advanced Divertor RF tokamak eXperiment (ADX)-a specifically designed to address critical gaps in the world fusion research programme on pathway next-step devices: nuclear science facility (FNSF), pilot plant (FPP) and/or demonstration power (DEMO). This high-field (>= 6.5 T, 1.5 MA), high density (P/S similar MW m(-2)) will test innovative divertor ideas, including an 'X-point target divertor' concept,...
Direction reversals of intrinsic toroidal rotation have been observed in diverted Alcator $C$-Mod Ohmic $L$-mode plasmas following electron density ramps. For low discharges, the core is directed cocurrent, and reverses to countercurrent an increase above a certain threshold. Such occur together with decrease fluctuations $2\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}1}\ensuremath{\le}{k}_{\ensuremath{\theta}}\ensuremath{\le}11\text{ }{\mathrm{cm}}^{\ensuremath{-}1}$ frequencies 70 kHz....
Direction reversals of intrinsic toroidal rotation have been observed in Alcator C-Mod ohmic L-mode plasmas following modest electron density or magnetic field ramps. The reversal process occurs the plasma interior, inside q = 3/2 surface. For low plasmas, is co-current direction, and can reverse to counter-current direction an increase above a certain threshold. Reversals from co- are correlated with sharp decrease fluctuations k R ⩾ 2 cm −1 frequencies 70 kHz. at which reverses increases...
The ITER design, and future reactor designs, depend on divertor 'detachment,' whether partial, pronounced or complete, to limit heat flux plasma-facing components surface erosion due sputtering. It would be valuable have a measure of the difficulty achieving detachment as function machine parameters, such input power, magnetic field, major radius, etc. Frequently parallel flux, estimated typically proportional Psep/R PsepB/R, is used proxy for this difficulty. Here we argue that impurity...
Using the MARS-F code (Liu et al 2000 Phys. Plasmas 7 3681), single fluid resistive MHD plasma response to applied n = 2 resonant magnetic perturbations is computed, for a discharge in ASDEX-Upgrade tokamak. The computation predicts strong kink amplification, as previously predicted DIII-D (Haskey 2014 Plasma Control. Fusion 56 035005), which strongly dependent on toroidal phase shift between upper and lower coils, . In particular, edge localised low peeling modes with poloidal mode numbers...
Owing to its high magnetic field, power, and compact size, the SPARC experiment will operate with divertor conditions at or above those expected in reactor-class tokamaks. Power exhaust this scale remains one of key challenges for practical fusion energy. Based on empirical scalings, peak unmitigated parallel heat flux is projected be greater than 10 GW m −2 . This nearly an order magnitude higher has been demonstrated date. Furthermore, Edge-Localized Mode (ELM) energy fluence projections...
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...
Neutron measurement is the primary tool in SPARC tokamak for fusion power (Pfus) monitoring, research on physics of burning plasmas, validation neutronics simulation workflows, and providing feedback machine protection. A demanding target uncertainty (10% Pfus) coverage a wide dynamic range (>8 orders magnitude going up to 5 × 1019 n/s), coupled with fast-track timeline design deployment, make development neutron diagnostics challenging. Four subsystems are under that exploit high...
Parametric dependences of the heat flux footprint on outer divertor target plate are explored in EDA H-mode and ohmic L-mode plasmas over a wide range parameters with attached plasma conditions.Heat profile shapes found to be independent toroidal field strength, power flow along magnetic lines insensitive x-point topology (single-null versus double-null).The magnitudes widths closely follow that "upstream" pressure profile, which correlated thermal energy content current.Heat decay lengths...
In the Alcator C-Mod tokamak, strong, steady-state variations of molybdenum density within a flux surface are routinely observed in plasmas using hydrogen minority ion cyclotron resonant heating. In/out asymmetries, up to factor 2, occur with either inboard or outboard accumulation depending on major radius resonance layer. These poloidal can be attributed impurity's high charge and large mass neoclassical parallel force balance. The enhances centrifugal force, causing while ion-impurity...
This research describes advancements in the spectral analysis and error propagation techniques associated with x-ray imaging crystal spectroscopy (XICS) that have enabled this diagnostic to be used accurately constrain particle, momentum, heat transport studies a tokamak for first time. Doppler tomography been extended include of statistical uncertainty due photon noise, effect non-uniform instrumental broadening as well flux surface variations impurity density. These methods deployed suite...