A5057546072- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Plasma Diagnostics and Applications
- Dust and Plasma Wave Phenomena
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Solar and Space Plasma Dynamics
- Laser-induced spectroscopy and plasma
- Atomic and Molecular Physics
- Nuclear reactor physics and engineering
- Earthquake Detection and Analysis
- Geomagnetism and Paleomagnetism Studies
- Electromagnetic Launch and Propulsion Technology
- Gyrotron and Vacuum Electronics Research
- Electron and X-Ray Spectroscopy Techniques
- Fluid Dynamics and Turbulent Flows
- High-pressure geophysics and materials
- Astro and Planetary Science
- Geophysics and Sensor Technology
- Nuclear Materials and Properties
- Vacuum and Plasma Arcs
- Particle Accelerators and Free-Electron Lasers
- Advanced Fiber Optic Sensors
Plasma Technology (United States)
2015-2024
Massachusetts Institute of Technology
2015-2024
Fusion Academy
2015-2024
Fusion (United States)
2012-2023
Lomonosov Moscow State University
2021
Space Research Institute
2021
PFA Consulting (United States)
2016
Moscow Institute of Thermal Technology
2012
Acadia University
2004
Cambridge University Press
1988-2002
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,...
As part of the ITER Design Review and in response to issues identified by Science Technology Advisory Committee, physics requirements were reviewed as appropriate updated. The focus this paper will be on recent work affecting design with special emphasis topics near-term procurement arrangements. This describe results on: sensitivity studies, poloidal field coil requirements, vertical stability, effect toroidal ripple thermal confinement, material choice heat load for plasma-facing...
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...
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...
A one-dimensional fluid theory of Langmuir probe operation in strong magnetic fields is presented. Cross-field diffusion ions both into and out the collection region consistently accounted for, effect taking momentum particle diffusivity to be equal. The results differ by significant factors from previous analyses, which did not account for outward but set zero. differences are especially large when parallel flow external plasma present. It thus clear that value assumed strongly affects...
This is a tutorial and selective review explaining the fundamental concepts some currently open questions concerning plasma phenomenon of electron hole. The widespread occurrence holes in numerical simulations, space-craft observations, laboratory experiments illustrated. elementary underlying theory developed one-dimensional hole as localized potential maximum, self-consistently sustained by deficit trapped phase-space density. spatial extent typically few Debye lengths; what determines...
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...
Divertor detachment may be essential to reduce heat loads magnetic fusion tokamak reactor divertor surfaces. Yet in experiments it is difficult control the extent of detached, low pressure, plasma region. At maximum front edge detached region reaches X-point and can lead degradation core properties. We define 'detachment window' a given position variable C (for example, upstream density) as range within which location stably held at any from target X-point; increased window corresponds...
Fluid-theory calculations are presented of ion collection by electric probes in strongly magnetized plasmas with parallel flow. In the first problem is treated a one-dimensional approximation but cross-field transport momentum included such way as to model different ratios viscosity diffusivity. The results show that flow deduced from probe measurements not particularly sensitive assumed viscosity, provided it finite. However, zero qualitatively those nonzero viscous transport. second set...
Impurity toroidal rotation has been observed in the centre of Alcator C-Mod ion cyclotron range frequencies (ICRF) heated plasmas, from Doppler shifts argon X ray lines. Rotation velocities greater than 1.2 × 107 cm/s (ω = 200 krad/s) co-current direction have H mode discharges that had no direct momentum input. There is a correlation between increase central impurity velocity and plasma stored energy (confinement enhancement), induced by ICRF heating, although other factors may be at play....
Although diagnostics are the essential tools of experimental plasma physicist, there surprisingly few up-to-date books in this field. Several excellent volumes appeared early days fusion research but these, though containing much material that is still relevant, now seriously out date with respect to substantial advances have taken place field over past decades. There course a vast amount information journal articles, conference papers and reviews, these generally aimed at experienced...
A set of external coils (A-coils) capable producing nonaxisymmetric, predominantly n=1, fields with different toroidal phase and a range poloidal mode m spectra has been used to determine the threshold amplitude for locking over plasma parameters in Alcator C-Mod [I. H. Hutchinson, R. Boivin, F. Bombarda, P. Bonoli, S. Fairfax, C. Fiore, J. Goetz, Golovato, Granetz, M. Greenwald et al., Phys. Plasmas 1, 1511 (1994)]. The perturbations parametric scalings, expressed terms (B21∕BT), are...
A new one-dimensional collisionless kinetic model is developed for the flow of ions to probing structures in drifting plasmas. The cross-field into presheath modeled by accounting consistently particle exchange between collection flux tube and outer plasma. Numerical solutions self-consistent plasma-sheath equations are obtained with arbitrary external ion temperature parallel plasma velocity. Results presented spatial dependence distribution function as well its moments (density, flux,...
The spatial distribution of collisionless ions collected by a spherical object radius much larger than the Debye length, in flowing plasma, is calculated using particle-in-cell code. results provide first rigorous theoretical calibration `Mach probe' plasma with negligible magnetic field. They are also applicable, for example, to spacecraft-plasma interactions. Ion electron temperature ratios 0.1<Ti/ZTe<10 explored. Qualitative differences observed between low and high Ti/ZTe, arising from...
The ion drag force on a spherical grain situated in flowing collisionless plasma is obtained from the specialized coordinate electrostatic particle and thermals cell simulation code (SCEPTIC) (Hutchinson 2002 Plasma Phys. Control. Fusion 44 1953, Hutchinson 2003 45 1477, 2005 47 71) compared with recent analytic approximate treatments interesting relevant case when Debye length only moderately larger than sphere radius. There substantial complex structure results for transonic flows, which...
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,...
Operating experimental devices have provided key inputs to the design process for ITER axisymmetric control. In particular, experiments quantified controllability and robustness requirements in presence of realistic noise disturbance environments, which are difficult or impossible characterize with modelling simulation alone. This kind information is particularly critical vertical control, poses highest demands on poloidal field system performance, since consequences loss control can be...
Radial observations of emission in the vicinity electron cyclotron frequency and its harmonics show radiation to be polarized; ratio extraordinary ordinary mode intensity about 2:1. In thermal spectra effects cold-plasma resonances upon propagation from layer observation point are evident: (i) The first harmonic is always suppressed by upper hybrid resonance layer; (ii) ordinary-mode when plasma exceeds frequency; (iii) For sufficiently high density second also affected cut-off. non-thermal...
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,...
Disruptions in Alcator C-Mod can generate large eddy currents the highly conducting vacuum vessel and internal structures, including a significant poloidal component due to halo currents. In order understand better stresses arising from resulting J*B forces, has been fitted with comprehensive set of sensors measure spatial distribution temporal behaviour It is found that they are toroidally asymmetric, typical peaking factor 2. The asymmetric pattern usually rotates at few kilohertz, thus...
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...