A5086759540- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Gyrotron and Vacuum Electronics Research
- Fusion materials and technologies
- Antenna Design and Analysis
- Electromagnetic Launch and Propulsion Technology
- Microwave Engineering and Waveguides
- Laser-Plasma Interactions and Diagnostics
- Metal and Thin Film Mechanics
- Electromagnetic Compatibility and Measurements
- Copper Interconnects and Reliability
- Electrostatic Discharge in Electronics
- Physics of Superconductivity and Magnetism
- Advanced Data Storage Technologies
- Antenna Design and Optimization
- Mechanical Behavior of Composites
- Microwave-Assisted Synthesis and Applications
- Underwater Vehicles and Communication Systems
- Nuclear Materials and Properties
- Advanced ceramic materials synthesis
- Electromagnetic Simulation and Numerical Methods
- Magnetic Field Sensors Techniques
Pennsylvania State University
1965-2024
Rutgers, The State University of New Jersey
2023
Washington University in St. Louis
2022
Arizona State University
2008
Applied Materials (United States)
2005-2007
Princeton Plasma Physics Laboratory
1990-2004
Oak Ridge National Laboratory
1990-2003
Princeton University
1990-2003
Martin Marietta Materials (United States)
2003
Babcock & Wilcox (United States)
2002
A study of the fluid model for cylindrical weakly ionized quasineutral plasmas in an axial magnetic field is presented. The takes into account ionization, ion and electron inertia, as well frictional forces ions electrons. behavior plasma parameters arbitrary magnitudes field, gas pressure, size presented, making applicable a wide range discharge conditions. parameter introduced, which specifies where Boltzmann equilibrium with ambipolar distribution satisfied. In addition, parametric...
Measurements of the toroidal rotation speed vφ(r) driven by neutral beam injection in tokamak plasmas and, particular, simultaneous profile measurements vφ, Ti, Te, and ne, have provided new insights into nature anomalous transport tokamaks. Low-recycling heated with unidirectional exhibit a strong correlation among local diffusivities, χφ≊χi>χe. Recent confirmed similar behavior broad-density L-mode plasmas. These results are consistent conjecture that electrostatic turbulence is...
Measurements of low power (≃ 1 mW) antenna loading are used to study the coupling a compact loop structure plasmas in divertor configuration DIII-D heated by neutral beam injection (NBI) or electron cyclotron heating (ECH). When transition H-mode regime occurs during NBI, resistance drops approximately factor two. This decrease is due steepening edge density profile near separatrix, accompanied reduction scrape-off layer. During localized modes, opposite effects occur, and increases...
The non-inductive current drive from directional fast Alfven and electron cyclotron waves was measured in the DIII-D tokamak order to demonstrate these forms of radiofrequency (RF) compare efficiencies with theoretical expectations. wave frequency 8 times deuterium at plasma centre, while twice frequency. Complete achieved using a combination (FWCD) (ECCD) discharges for which total inductively ramped down 400 170 kA. For steady discharges, an analysis loop voltage revealed up 195 kA (out...
Results obtained from experiments utilizing high-power ion cyclotron range of frequencies (ICRF) heating to stabilize sawtooth oscillations on Tokamak Fusion Test Reactor (TFTR) [Hawryluk et al., Plasma Phys. Controlled 33, 1509 (1991)] are reviewed. The key observations include existence a minimum ICRF power required achieve stabilization, dependence the stabilization threshold relative size deposition profile q=1 volume, and peaking equilibrium pressure current profiles during...
A dual frequency rf sheath is analyzed using a simple model to study the interaction between two driving currents and their effect on parameters. symmetric discharge with defined electron density dc potential modeled sharp boundary approximation. Three results of this are reported: (1) reproduction trends in ion energy distribution functions predicted measured previous studies, (2) frequency-mixing-dependent relationship applied potential, (3) an additional asymmetry function generated by...
Magnetohydrodynamic (MHD) activity within three zones (core, half-radius, and edge) of TFTR [Plasma Physics Controlled Nuclear Fusion Research 1986 (IAEA, Vienna, 1987), Vol. 1, p. 51] tokamak plasmas are discussed. Near the core plasma column, sawteeth often observed. Two types studied in detail; one with complete, other incomplete, magnetic reconnection. Their characteristics determined by shape q profile. half-radius m/n=3/2 2/1 resistive ballooning modes found to correlate a beta...
The three dimensional (3-D) nature of antennas for fusion applications in the ion cyclotron range frequencies (ICRF) requires accurate modelling to design and analyse new antennas. In this article, analysis tools radiofrequency (RF) are successfully benchmarked with experiment, 3-D physics launched waves is explored. systematic combines measured density profiles from a reflectometer system, transmission line circuit modelling, detailed magnetostatics electromagnetic antenna model including...
Efficient direct heating of electrons by fast waves has been observed on the DIII-D tokamak. The measured fast-wave efficiency was independent magnetic field, in contrast to strong inverse field scaling predicted theory single-pass damping, indicating multiple-pass absorption. central had a dependence target eelctron temperature. H-mode plasmas were obtained with alone for first time electron regime.
An ion cyclotron range of frequencies (ICRF) heating experiment was performed on the Compact Helical System (CHS) device in order to identify problems establishing this as a reliable method. Radiofrequency applied plasmas with two species produced by ECH. Stored energy increased upto 2.2 kJ application 590 kW ICRF pulse, giving efficiency comparable that NBI heating. More importantly, `flat-top' stored maintained during pulse. Good realized 30% proton and 70% deuteron at high density (4*1019...
Research on the spherical torus (or tokamak) (ST) is being pursued to explore scientific benefits of modifying field line structure from that in more moderate aspect ratio devices, such as conventional tokamak. The ST experiments are conducted various US research facilities including MA-class National Spherical Torus Experiment (NSTX) at Princeton, and three medium sized facilities: PEGASUS University Wisconsin, HIT-II Washington, CDX-U Princeton. In context fusion energy development path...
Current drive experiments have been performed on the DIII-D tokamak using fast waves, electron cyclotron and neutral injection. Fast wave were a 4-strap antenna with 1 MW of power at 60 MHz. These showed effective heating electrons, global efficiency equivalent to that injection even when single pass damping was calculated be as small 5%. The probably due effect multiple passes through plasma. current toroidally directional phasing straps. Currents driven by (FWCD) in direction main plasma...
Magnetic fields can be used to enhance the performance and operational envelope of rf capacitive discharges for semiconductor processing. Antennas in magnetized experimental fusion devices experience similar processes that lead surface erosion degraded antenna performance. Two-dimensional modeling is needed understand combined effects production transport these plasmas; however, plasma a complicated medium because tensor conductivity, anisotropic transport, fact power alone sustains plasma....
Design of an all-in-one (main etch, PR ash and clean) dielectric etch chamber requires independent control plasma generation from ion energy. Plasma simulation has been performed for a capacitively coupled discharge to study frequency effect on electron density, power deposition, dissociation fraction. Simulation results demonstrate that production efficiency enhances with increase in while energy the bombarding ions diminishes. A very high source developed generate density radio bias used...
The increased core electron temperature produced by ICRF heating of TFTR, D-T neutral-beam-heated supershot plasmas is expected to extend the alpha-particle slowing down time and hence enhance central pressure. In preparation for TFTR operational phase, which started in late 1993, a series experiments were conducted on explore effect performance stability low-recycling, deuterium 3He minority regime. coupling up 7.4 MW 47 MHz power full size (R approximately 2.62 m, 0.96 m), minority,...
Fast wave heating experiments in the ion cyclotron range of frequencies (ICRF) were performed on target plasmas produced by 350 kW electron at 53 GHz and also neutral beam injection Advanced Toroidal Facility (ATF). Various regimes investigated frequency between 9.2 MHz 28.8 with magnetic fields 0.95 T 1.9 axis. The nominal pulse lengths up to 200 RF power 100 400 ms. Data from spectroscopy, loading measurements, edge Langmuir probes used characterize induced effects ATF plasma. In hydrogen...
Abstract
It is well known that the plasma equations, with or without a magnetic field present, have singularity at point where ions reach ion sound speed. In his comment to our paper, J. E. Allen [Phys. Plasmas 14, 024701 (2007)] tries explain phenomenon by claiming Boltzmann electron distribution must hold near boundary even for magnetized plasmas. His claim, however, contradicts theoretical and numerical results of he seems agree with.
AbstractUnderstanding ion cyclotron range of frequency (ICRF) antenna interaction with the edge/scrape-off-layer (SOL) plasma is crucial to building antennas that can survive long-pulse or steady-state high-power operation in plasmas. The global effects ICRF/edge interactions are discussed. present knowledge ICRF-induced sheath edge and SOL plasmas magnetic fusion experiments quantitatively reviewed added to. design principles equations governing heat loading sputtering Faraday shields...