A5038848360- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Fusion materials and technologies
- Solar and Space Plasma Dynamics
- Superconducting Materials and Applications
- Fluid Dynamics and Turbulent Flows
- Particle accelerators and beam dynamics
- Astro and Planetary Science
- Plasma Diagnostics and Applications
- Nuclear Physics and Applications
- Geomagnetism and Paleomagnetism Studies
- Atomic and Subatomic Physics Research
- Laser-induced spectroscopy and plasma
- Astrophysics and Star Formation Studies
- Aerodynamics and Fluid Dynamics Research
- Metallurgical Processes and Thermodynamics
- Advanced MRI Techniques and Applications
- Ultrasonics and Acoustic Wave Propagation
- Stellar, planetary, and galactic studies
- Calibration and Measurement Techniques
- High-pressure geophysics and materials
- Earthquake Detection and Analysis
- Nuclear reactor physics and engineering
- Adaptive optics and wavefront sensing
State University of New York
2025
SUNY Cortland
2018-2024
Massachusetts Institute of Technology
2005-2022
Plasma Technology (United States)
2003-2022
Fusion Academy
2003-2022
General Atomics (United States)
2022
Max Planck Institute for Plasma Physics
2019-2020
Max Planck Society
2019-2020
Southwest Research Institute
2013-2020
California State University, San Marcos
2019
The HOPE mass spectrometer of the Radiation Belt Storm Probes (RBSP) mission (renamed Van Allen Probes) is designed to measure in situ plasma ion and electron fluxes over 4π sr at each RBSP spacecraft within terrestrial radiation belts. scientific goal understand underlying physical processes that govern belt structure dynamics. Spectral measurements for both ions electrons are acquired 1 eV 50 keV 36 log-spaced steps an energy resolution ΔE FWHM/E≈15 %. dominant species (H+, He+, O+)...
The Solar Orbiter mission seeks to make connections between the physical processes occurring at Sun or in solar corona and nature of wind created by those which is subsequently observed spacecraft. also targets itself during its journey from source To meet specific science goals, will be equipped with both remote-sensing in-situ instruments unprecedented measurements atmosphere inner heliosphere. A crucial set provided Wind Analyser (SWA) suite instruments. This consists an Electron System...
Abstract The optimized superconducting stellarator device Wendelstein 7-X (with major radius , minor and plasma volume) restarted operation after the assembly of a graphite heat shield 10 inertially cooled island divertor modules. This paper reports on results from first high-performance operation. Glow discharge conditioning ECRH discharges in helium turned out to be important for density edge radiation control. Plasma densities with central electron temperatures were routinely achieved...
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...
Remarkable progress has been made in diagnosing energetic particle instabilities on presentday machines and establishing a theoretical framework for describing them.This overview describes the much improved diagnostics of Alfvén modelling tools developed world-wide, discusses interpreting observed phenomena.A multi-machine comparison is presented giving information performance both different plasma conditions outlining expectations ITER based our present knowledge.
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.,...
Experiments in a modified Taylor-Couette device, spanning Reynolds numbers of ${10}^{5}$ to greater than ${10}^{6}$, reveal the nonlinear stability astrophysically relevant flows. Nearly ideal rotation, expected absence axial boundaries, is achieved for narrow range operating parameters. Departures from optimal control parameters identify centrifugal instability boundary layers as primary source turbulence observed former experiments. By driving perturbations series jets we demonstrate...
New results on the I-mode regime of operation Alcator C-Mod tokamak are reported. This ELM-free features high energy confinement and a steep temperature pedestal, while particle remains at L-mode levels, giving stationary density avoiding impurity accumulation. has now been obtained over nearly all magnetic fields currents possible in this field (Ip 0.55–1.7 MA, BT 2.8–8 T) using configuration with B × ∇B drift away from X-point. Results 8 T confirm that L–I power threshold varies only...
Phase contrast imaging (PCI) is an internal reference beam interferometry technique which provides a direct image of line integrated plasma density fluctuations. The method has been used with great success to measure waves and turbulence in magnetically confined high temperature plasmas. principle PCI was developed optics the 1930s by Dutch physicist Zernike, leading development phase-contrast microscopy. allows one detect variation index refraction dielectric medium (such as plasma) due...
Recent advances in gyrokinetic simulation of core turbulence and associated transport requires an intensified experimental effort to validate these codes using state the art synthetic diagnostics compare simulations with data. A phase contrast imaging (PCI) diagnostic [M. Porkolab, J. C. Rost, N. Basse et al., IEEE Trans. Plasma Sci. 34, 229 (2006)] is used study H-mode plasmas Alcator C-Mod Greenwald, D. Andelin, Nucl. Fusion 45, S109 (2005)]. The PCI system capable measuring density...
Performance predictions for future fusion devices rely on an accurate model of the pedestal structure. The candidate predictive structure is EPED, and it imperative to test underlying hypotheses further gain confidence ITER projections. Here, we present experimental work testing one EPED hypotheses, namely existence a soft limit set by microinstabilities such as kinetic ballooning mode. This extends recent Alactor C-Mod (Diallo et al 2014 Phys. Rev. Lett. 112 115001), include detailed...
The BOUT++ code has been exploited in order to improve the understanding of role turbulent modes controlling edge transport and resulting scaling scrape-off layer (SOL) heat flux width. For C-Mod enhanced (EDA) H-mode discharges, six-field two-fluid nonlinear simulations show a reasonable agreement upstream turbulence divertor target behavior: (a) simulated quasi-coherent consistent characteristics frequency versus poloidal wave number spectra electromagnetic fluctuations when compared with...
In this Letter, we demonstrate by comparison of computer simulations and experimental results that excitation turbulence-driven electromagnetic secondary instabilities can serve as a paradigm to explain the observed activity otherwise stable modes in fusion devices. particular, discuss Alfvén eigenmodes electron cyclotron heated plasmas Wendelstein 7-X (W7-X) stellarator. more than 700 programs W7-X Operational Phase 1.2b (from which 25 were selected discussed paper), poloidal magnetic...
Global and local transport experiments in ohmic, L-mode H-mode regimes on the Alcator C-Mod tokamak are summarized. For ohmic plasmas, earlier results derived for energy confinement scaling (linear) regime have been confirmed, saturated has shown to be equivalent that of L-mode. auxiliary heated regimes, provided a unique laboratory test standard laws had previously derived. C-Mod's performance matches quite well, but times were about 50% above existing laws. This difference was significant...
Recent advances in gyrokinetic simulation have allowed for quantitative predictions of core turbulence and associated transport. However, numerical codes must be tested against experimental results both In this paper, we present recent from ohmic plasmas the Alcator C-Mod tokamak using phase contrast imaging (PCI) diagnostic, which is capable measuring density fluctuations with wave numbers up to 55 cm−1. The experiments were carried out over range densities covering 'neo-Alcator' (linear...
We report on observations of a free-Shercliff-layer instability in Taylor-Couette experiment using liquid metal over wide range Reynolds numbers, $\mathrm{Re}\ensuremath{\sim}{10}^{3}--{10}^{6}$. The free Shercliff layer is formed by imposing sufficiently strong axial magnetic field across pair differentially rotating end cap rings. This destabilized hydrodynamic Kelvin-Helmholtz-type instability, characterized velocity fluctuations the $r\mathrm{\text{\ensuremath{-}}}\ensuremath{\theta}$...
This paper summarizes highlights of research results from the Alcator C-Mod tokamak covering period 2006–2008. Active flow drive, using mode converted ion cyclotron waves, has been observed for first time in a plasma, mix D and 3 He species; toroidal poloidal flows are driven near location conversion layer. ICRF induced edge sheaths implicated both erosion thin boron coatings generation metallic impurities. Lower hybrid range frequencies (LHRF) microwaves have used efficient current profile...
Groups of frequency chirping modes observed between sawtooth crashes in the Alcator C-Mod tokamak are interpreted as reversed shear Alfv\'en eigenmodes near $q=1$ surface. These indicate that a $q$ profile is generated during relaxation phase cycle. Two important parameters, ${q}_{\mathrm{min}}$ and its radial position, deduced from comparisons measured density fluctuations with calculations ideal MHD code NOVA. studies provide valuable constraints for further modeling
A phase contrast imaging (PCI) diagnostic has been developed for the Wendelstein 7-X (W7-X) stellarator. This diagnostic, funded by U.S. Department of Energy through Office Fusion Sciences, is a collaboration between Max Planck Institute Plasmaphysics, MIT, and SUNY Cortland. The primary motivation development PCI measurement turbulent fluctuations, such as ion temperature gradient, electron trapped mode instabilities. Understanding how magnetic geometry other externally controllable...
First experimental observations in the Wendelstein 7-X stellarator indicate that impurity confinement can be explained by turbulent processes. In particular, plasma discharges with increased ion to electron temperature ratio are accompanied reduced density fluctuation amplitudes and anomalous diffusion, suggesting a lower transport. Employing gyro-kinetic numerical simulations, we argue plays key role for reducing gradient instability 7-X, leading an enhanced confinement.
The fundamental nature of turbulent density fluctuations in standard Wendelstein 7-X (W7-X) stellarator discharges is investigated experimentally via phase contrast imaging (PCI) combination with gyrokinetic simulations the code GENE. We find that are ion-temperature-gradient-driven and radially localised outer half plasma. It shown line-integrated PCI measurements cover right range wavenumbers a favourable toroidal poloidal location to capture some strongest W7-X. Due radial localisation...
Phase contrast imaging (PCI) diagnostic has been used to study mode conversion physics of ion cyclotron range frequency waves [E. Nelson-Melby et al., Phys. Rev. Lett. 90, 155004 (2003)], plasma turbulence [A. Mazurenko 89, 225004 (2002); N. Basse Plasmas 12, 052512 (2005)], and Alfvén Cascades [M. Porkolab IEEE Trans. Plasma Sci. 34, 229 (2006)] in Alcator C-Mod. The C-Mod PCI system measures line integrated electron density fluctuations along 32 vertical chords with a sampling 10MHz...