A5041094682- Magnetic confinement fusion research
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Plasma Diagnostics and Applications
- Hedgehog Signaling Pathway Studies
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Atomic and Molecular Physics
- X-ray Spectroscopy and Fluorescence Analysis
- Laser-induced spectroscopy and plasma
- Electron and X-Ray Spectroscopy Techniques
- Medical Imaging Techniques and Applications
- Nuclear reactor physics and engineering
- Advanced X-ray Imaging Techniques
- Gyrotron and Vacuum Electronics Research
- Silicon and Solar Cell Technologies
- Metal and Thin Film Mechanics
- Antenna Design and Analysis
- Advanced X-ray and CT Imaging
- Nuclear Materials and Properties
- Spacecraft and Cryogenic Technologies
- Advanced MRI Techniques and Applications
University of Wisconsin–Madison
2014-2025
Tecplot (United States)
2023-2025
University of Notre Dame
2024
Ste. Genevieve County Memorial Hospital
2019
Ohio University
2014
Dartmouth College
2005
Plasma Technology (United States)
1994-2002
Fusion Academy
1994-2002
Fusion (United States)
1994-2002
Princeton Plasma Physics Laboratory
2001
Early operation of the Alcator-C-MOD tokamak [I.H. Hutchinson, Proceedings IEEE 13th Symposium on Fusion Engineering, Knoxville, TN, edited by M. Lubell, Nestor, and S. Vaughan (Institute Electrical Electronic Engineers, New York, 1990), Vol. 1, p. 13] is surveyed. Reliable operation, with plasma current up to 1 MA, has been obtained, despite massive conducting superstructure associated error fields. However, vertical disruptions are not slowed long vessel time constant. With pellet fueling,...
A series of experiments, examining the confinement properties ion cyclotron range frequencies (ICRF) heated H mode plasmas, has been carried out on Alcator C-Mod tokamak. is a compact tokamak that operates at high particle, power and current densities toroidal fields up to 8 T. Under these conditions plasma essentially thermal with very little contribution stored energy from energetic ions (typically no more than 5%) Ti~Te. Most data were taken machine in single null `closed' divertor...
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...
Cross-field particle transport increases sharply with distance into the SOL and plays a dominant role in `main-chamber recycling' regime Alcator C-Mod, which most of plasma efflux recycles on main-chamber walls rather than flows divertor volume. This observation has potentially important implications for reactor: contrary to ideal picture operation, tightly baffled may not offer control neutral density such that charge exchange heat losses sputtering can be reduced. The conditions give rise...
Central impurity toroidal rotation has been observed in Alcator C-Mod ICRF heated plasmas, from the Doppler shifts of argon X ray lines. Rotation velocities up to 1.3 × 105 m/s co-current direction have H mode discharges with no direct momentum input. There is a strong correlation between increase central velocity and plasma stored energy, induced by heating, although other factors may be involved. This implies close association energy confinement. Co-current also during purely ohmic modes....
Co-current central impurity toroidal rotation has been observed in Alcator C-Mod plasmas with on-axis ICRF heating. The velocity increases plasma stored energy and decreases current. Very similar behaviour seen during ohmic H modes, which suggests that the rotation, generated absence of an external momentum source, is not mainly effect. A scan resonance location across performed order to investigate possible influences on rotation. With a slight reduction magnetic field from 4.7 4.5 T...
Detailed measurements and transport analysis of divertor conditions in Alcator C-Mod [Phys. Plasmas 1, 1511 (1994)] are presented for a range line-averaged densities, 0.7<n̄e<2.2×1020 m−3. Three parallel heat regimes evident the scrape-off layer: sheath-limited conduction, high-recycling divertor, detached which can coexist same discharge. Local cross-field pressure gradients found to scale simply with local electron temperature. This scaling is consistent classical conduction...
Studies of the enhanced Dα H-mode (EDA) have been extended to include ohmic plasmas. No clear difference in EDA/ELMfree boundary or other phenomenology are seen between and ICRF-heated plasmas, suggesting that neither effect ion tails nor direct RF/edge plasma interaction plays a role EDA. Edge safety factor (q95) is principal variable which determines regime discharge will be in. When q95 greater than 4.0 for standard-shaped almost always EDA, while when it less 3.5, ELMfree. New edge...
Enhanced confinement modes up to a toroidal field of BT=8 T have been studied with 3.5 MW radiofrequency (rf) heating power in the ion cyclotron range frequencies (ICRF) at 80 MHz. H-mode is observed when edge temperature exceeds threshold value. The high mode (H-mode) higher enhancement factors (H) and longer duration became possible after boronization by reducing radiated from main plasma. A quasi-steady state (H=2.0), normalized beta (βN=1.5), low fraction (Pradmain/Ploss=0.3), effective...
Energy confinement comparable with tokamak quality is achieved in the Madison Symmetric Torus (MST) reversed field pinch (RFP) at a high beta and low toroidal magnetic field. Magnetic fluctuations normally present RFP are reduced via parallel current drive outer region of plasma. In response, electron temperature nearly triples doubles. The time increases ten-fold (to ∼10 ms), which L- H-mode scaling values for same plasma current, density, heating power, size shape. Runaway evidenced by...
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Neutral particle densities and energy losses have been measured in the Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. Their effect on formation evolution of edge barrier which accompanies enhanced confinement regime are discussed. The neutrals can enter dynamics through particle, momentum, balance. up to 5×1016 m−3 region. Neutrals local around most periphery, not just at X-point. High resolution measurements ionization profile obtained for region near separatrix....
Trace non-recycling impurities have been injected into Alcator C-Mod [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] plasmas in order to determine impurity transport coefficients. Subsequent emission has observed with spatially scanning x-ray and Vacuum Ultra-Violet (VUV) spectrometer systems. Measured time-resolved brightness profiles of helium- lithium-like transitions compared those calculated from a code which includes diffusion convection conjunction an atomic physics package...
Imbalances between the inboard and outboard legs of single null divertor in tokamak Alcator C-Mod are observed to reverse when direction toroidal field is reversed. These imbalances measured by embedded probes target plates, tomographic reconstructions bolometry line radiation, visible imaging. Density about a factor ten at targets moderate density, decreasing as density raised until they almost balanced. The data indicate that electron pressure not imbalanced, thus arguing against momentum...
Recent breakthroughs in silicon detector technology now permit measurement of radiated power over a wide range photon energies. These detectors (also known as AXUV photodiodes) have flat spectral response from ultraviolet to x-ray energies, and with slightly reduced efficiency all the way down visible wavelengths. Since they can be made small, multichannel allow high spatial resolution combined an intrinsic temporal resolution, which reach microsecond range, depending on application....
Central toroidal rotation and impurity transport coefficients have been determined in Alcator C-Mod [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] Ohmic high confinement mode (H-mode) plasmas from observations of x-ray emission following injection. Rotation velocities up to 3×104 m/sec the co-current direction observed center best H-mode plasmas. Purely ohmic display many characteristics similar ion cyclotron range frequencies (ICRF) heated plasmas, including scaling velocity with...