A5005107647- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Electromagnetic Launch and Propulsion Technology
- Engineering Applied Research
- Solar and Space Plasma Dynamics
- Nuclear Physics and Applications
- Gyrotron and Vacuum Electronics Research
- Metal and Thin Film Mechanics
- Dust and Plasma Wave Phenomena
- Antenna Design and Analysis
- Microwave Engineering and Waveguides
- Metallurgical Processes and Thermodynamics
- Nuclear Materials and Properties
- High-pressure geophysics and materials
- Antenna Design and Optimization
- Quantum Dots Synthesis And Properties
- Crystallization and Solubility Studies
- Diamond and Carbon-based Materials Research
- Spacecraft and Cryogenic Technologies
- X-ray Diffraction in Crystallography
Massachusetts Institute of Technology
2011-2024
Fusion Academy
2013-2024
Fusion (United States)
2013-2024
Plasma Technology (United States)
2015-2024
Changchun University of Science and Technology
2024
The University of Tokyo
2023-2024
Hangzhou Dianzi University
2022-2024
National Kaohsiung University of Science and Technology
2023
National Kaohsiung Marine University
2023
University of Science and Technology
2023
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...
Plasma profiles and flows in the low- high-field side scrape-off-layer (SOL) regions Alcator C-Mod are found to be remarkably sensitive magnetic separatrix topologies (upper-, lower- double-null) impose topology-dependent flow boundary conditions on confined plasma. Near-sonic plasma along field lines observed SOL, with magnitude direction clearly dependent X-point location. The principal drive mechanism for is a strong ballooning-like poloidal transport asymmetry: parallel arise so as...
Regimes of high-confinement mode have been studied in the Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. with no edge localized modes (ELM-free) compared detail to a new regime, enhanced Dα (EDA). EDA discharges only slightly lower energy confinement than comparable ELM-free ones, but show markedly reduced impurity confinement. Thus do not accumulate impurities and typically fraction radiated power. The gradients seem be relaxed by continuous process rather an...
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...
Anomalous momentum transport has been observed in Alcator C-Mod tokamak plasmas. The time evolution of core impurity toroidal rotation velocity profiles measured with a tangentially viewing crystal x-ray spectrometer array. Following the L-mode to EDA (enhanced Dα) H-mode transition both Ohmic and ion cyclotron range frequencies heated discharges, ensuing co-current velocity, which is generated absence any external source, propagate from edge plasma timescale order energy confinement time,...
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,...
SPARC is designed to be a high-field, medium-size tokamak aimed at achieving net energy gain with ion cyclotron range-of-frequencies (ICRF) as its primary auxiliary heating mechanism. Empirical predictions conservative physics indicate that baseline plasmas would reach $Q\approx 11$ , which well above mission objective of $Q>2$ . To build confidence will successful, physics-based integrated modelling has also been performed. The TRANSP code coupled the theory-based trapped gyro-Landau...
Factor of ∼2 higher power thresholds for low- to high-confinement mode transitions (L-H) with unfavorable x-point topologies in Alcator C-Mod [Phys. Plasmas 1, 1511 (1994)] are linked flow boundary conditions imposed by the scrape-off layer (SOL). Ballooning-like transport drives along magnetic field lines from high-field regions toroidal direction dependent on upper/lower balance; rotation confined plasma responds, exhibiting a strong counter-current when B×∇B points away x point. Increased...
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...
Ion cyclotron range of frequency (ICRF) heating is expected to provide auxiliary for ITER and future fusion reactors where high Z metallic plasma facing components (PFCs) are being considered. Impurity contamination linked ICRF antenna operation remains a major challenge particularly devices with PFCs. Here, we report on an experimental investigation test whether field aligned (FA) can reduce impurity sources. We compare the modification scrape layer (SOL) potential FA conventional,...
Ion cyclotron range of frequencies (ICRF) heating will be the sole auxiliary method on SPARC for both full-field ( B t 0 ~ 12 T) D–T operation and reduced field 8 D–D operation. Using fast wave at ~120 MHz, good penetration strong single-pass absorption is expected D–T( 3 He), D( D(H) 4 He(H) scenarios. The dependences ${k_\parallel }$ , He concentration, resonance location, antenna poloidal location losses alpha particles ash have been studied. loading has assessed by comparison with...
We report a Cu(II)-catalyzed C-H amidation/cyclization of azomethine imines with dioxazolones as acyl nitrene transfer reagents under additive- and ligand-free conditions. An array 1,2,4-triazolo[1,5-a]pyridine derivatives were afforded in moderate to good yields excellent functional group tolerance. In addition, scale-up reaction photoluminescence properties discussed.
The HMnO 2 –VC@mPEG–Ce6 nanoplatform synergizes sono–chemodynamic therapy with ferroptosis induction via hypoxia alleviation, GSH depletion, and GPX4 inhibition, achieving tumor suppression in prostate cancer minimal systemic toxicity.
Double transport barrier plasmas comprised of an edge enhanced Dα (EDA) H-mode pedestal and internal (ITB) have been observed in Alcator C-Mod. The ITB can be routinely produced ICRF heated by locating the wave resonance off-axis near |r/a|~0.5, provided target plasma average density is above ~1.4×1020 m-3, develop spontaneously some Ohmic discharges. formation appears conjunction with a decrease or reversal central (impurity) toroidal rotation velocity. foot located r/a~0.5, regardless how...
High resolution measurements on the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1551 (1994)] of transport barrier in “Enhanced Dα” (EDA) regime, which has increased particle without large edge localized modes, show steep density and temperature gradients over a region 2–5 mm, with peak pressure up to 12 MPa/m. Evolution pedestal at L-H transition is consistent large, rapid drop thermal conductivity across barrier. A quasi-coherent fluctuation density, potential, Bpol,...
Two aspects of edge turbulence and transport in Alcator C-Mod are explored. The quasi-coherent mode (QCM), an fluctuation present Enhanced Dα H-mode plasmas, is examined with regard to its role the enhanced particle found these in/out asymmetry, poloidal wave number radial width location. It shown play a dominant perpendicular transport. QCM not observed at inboard midplane, indicating that amplitude there significantly smaller than on outboard side. peak just inside separatrix, ≳5 mm,...
This paper reviews the physics and technology of wave-particle-interaction experiments in ion cyclotron range frequencies (ICRF) lower hybrid (LH) (LHRF) on Alcator C-Mod tokamak. Operation fixed frequency (80 MHz) tunable (40- to 80-MHz) ICRF transmitters associated transmission system is described. Key fabrication issues that were solved order operate a four-strap antenna compact environment are discussed some detail. heating utilizing hydrogen (H) helium-3 (3He) minority schemes...
Alfvén eigenmodes (AEs) are studied to assess their stability in high density reactor relevant regimes where Ti≈Te and as a diagnostic tool. Stable AEs excited with active magnetohydrodynamics antennas the range of expected AE frequency. Toroidal eigenmode (TAE) damping rates between 0.5%<γ∕ω<4.5% have been observed diverted limited Ohmic plasmas. Unstable fast ion tail driven by H minority cyclotron radio frequency (ICRF) heating electron densities n¯e=0.5–2×1020m−3. Energetic...
An overview of the diagnostics installed on Alcator C-Mod tokamak is presented. Approximately 25 diagnostic systems are being operated C-Mod. The compact design machine and cryostat enclosing vacuum vessel magnetic field coils make access challenging. Diagnostics used to study four focus areas: transport, plasma boundary, waves, macrostability. There significant overlap between these topics, they all contribute toward burning advanced thrusts. Several novel investigation plasmas, e.g.,...
Studies of potential plasma facing component (PFC) materials for a magnetic fusion reactor generally conclude that tungsten is the best choice due to its low tritium (T) retention, capability handle high heat fluxes with erosion, and robustness nuclear damage activation. ITER [F. Perkins et al., Nucl. Fusion 39, 2137 (1999)] may operate all PFCs provide necessary operational experience reactor. Alcator C-Mod [I. Hutchinson Phys. Plasmas 1, 1511 (1994)] operates molybdenum (Mo) high-Z PFCs,...
Multi-channel transport experiments have been conducted in auxiliary heated (Ion Cyclotron Range of Frequencies) L-mode plasmas at Alcator C-Mod [Marmar and Group, Fusion Sci. Technol. 51(3), 3261 (2007)]. These provide good diagnostic coverage for measurements kinetic profiles, impurity transport, turbulence (electron temperature density fluctuations). In the experiments, a steady sawtoothing plasma with 1.2 MW on-axis RF heating is established scanned by 20%. Measured rotation profiles...