A5002163371- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Plasma Diagnostics and Applications
- Combustion and Detonation Processes
- Laser-induced spectroscopy and plasma
- Computational Fluid Dynamics and Aerodynamics
- Nuclear Physics and Applications
- Plasma and Flow Control in Aerodynamics
- Superconducting Materials and Applications
- Gas Dynamics and Kinetic Theory
- Geomagnetism and Paleomagnetism Studies
- Lightning and Electromagnetic Phenomena
- Fusion materials and technologies
- Laser Design and Applications
- Advanced Optical Sensing Technologies
- Particle accelerators and beam dynamics
- Astro and Planetary Science
- Engineering Applied Research
- Vacuum and Plasma Arcs
- Fluid Dynamics and Turbulent Flows
- Atomic and Molecular Physics
- Meteorological Phenomena and Simulations
- Ion-surface interactions and analysis
Lawrence Livermore National Laboratory
2014-2025
Los Alamos National Laboratory
2010-2014
Massachusetts Institute of Technology
1994-2012
Plasma Technology (United States)
2005-2012
Fusion Academy
2005-2012
Fusion (United States)
2005-2012
University of Toronto
2002
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...
Magneto-inertial fusion (MIF) approaches take advantage of an embedded magnetic field to improve plasma energy confinement by reducing thermal conduction relative conventional inertial (ICF). MIF reduces required precision in the implosion and convergence ratio. Since 2008 (Wurden et al IAEA Fusion Energy Conf. (Geneva, Switzerland, 13–18 October) IC/P4-13 LA-UR-08-0796) since our prior refereed publication on this topic (Degnan IEEE Trans. Plasma Sci. 36 80), AFRL LANL have developed...
We consider propagation of coherent light through a nonlinear periodic optical structure consisting two alternating layers with different linear and refractive indices. A coupled-mode system is derived from the Maxwell equations analyzed for stationary-transmission regimes time-dependent dynamics. find domain existence true all-optical limiting when input–output transmission characteristic monotonic clamped below value output intensity. True can be managed by compensating Kerr nonlinearities...
Measurements and simulations show that plasma relaxation processes in the reversed field pinch drive redistribute both magnetic flux momentum. To examine this process, a new 3D Mach B-dot probe has been constructed. This collects ion saturation currents through six molybdenum electrodes arranged on flattened vertices of an octahedron made boron nitride (BN). The current flows configurable voltage dividers for measurement returns one selectable return equally spaced along 12 cm BN arm. In...
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...
We show experimentally for the first time that two mutually attracting flux ropes may bounce back instead of merging together, leading to a variety dynamics not expected from two-dimensional model. Attraction forces due rope currents compete with repulsion field line bending in-plane and out-of-plane magnetic fields elastic plasma compression. Bouncing occurs if line-bending force an dominates. Otherwise, merge. Further reduction in results violently erratic states.
The stability properties of Alfvén eigenmodes (AEs) are investigated directly using external antenna excitation and detection stable modes in a variety plasma configurations different devices. Dedicated methods to measure the AE damping rate separately from fast ion drive have been pioneered at JET, low toroidal mode number internal saddle coil antennas. Other experiments since installed localized in-vessel antennas detect MHD frequency range, first on C-Mod, then MAST. Experiments C-Mod...
Measured damping rates of stable Toroidal Alfvén Eigenmodes (TAEs) have been compared with calculated the NOVA-K code for a number experimental conditions on Alcator C-Mod in an attempt to validate model.Very low amplitude ( / B θ ~ 10 -7 at wall) TAEs are excited Ohmic plasmas pair active MHD antennas inside C-Mod.By sweeping frequency through expected TAE frequency, width mode resonance can be measured poloidal field pick-up coils outboard limiters determine rate that mode.The equilibrium...
Summary form only given. The goal of the Field-Reversed Configuration Heating Experiment (FRCHX) is to demonstrate magnetized plasma compression and thereby provide a low cost approach high energy density laboratory (HEDLP) studies, which include such topics as magneto-inertial fusion (MIF). A requirement for field-reversed configuration (FRC) that trapped flux in FRC must maintain confinement within capture region long enough process be completed, approximately 20 microseconds FRCHX....
Abstract Volcanic jet flows in explosive eruptions emit radio frequency signatures, indicative of their fluid dynamic and electrostatic conditions. The emissions originate from sparks supported by an electric field built up the ejected charged volcanic particles. When shock-defined, low-pressure regions confine sparks, signatures may be limited to high-frequency content corresponding early components avalanche-streamer-leader hierarchy. Here, we image a standing shock together transient...
Flux ropes form basic building blocks for magnetic dynamics in many plasmas, are macroscopic analogues of field lines, and irreducibly three dimensional (3D). We have used the relaxation scaling experiment (RSX) to study flux ropes, found new features involving 3D dynamics, kink instability driven reconnection, nonlinearly stable but kinking large flows.
Abstract Ion cyclotron resonance heating is the primary auxiliary on Alcator C-Mod tokamak and commonly used other devices, planned for use ITER. The RF-power density above 5 MW m −3 providing a unique opportunity to study wave–particle effects in high RF power per particle regime. Minority produces highly energetic tail minority distribution function which measured using compact neutral analyser. In this paper, we present measurements of fast-ion spectrum between 200 2 MeV, compiled over an...
Conversions between magnetic and kinetic energy occur over a range of plasma scales in astrophysical solar dynamos reconnection the corona laboratory. Canonical flux tubes reconcile all regimes with concepts twists, writhes, linkages. We present measurements canonical tubes, their helicity, helicity transport gyrating kink. The gauge is removed general techniques valid even if only limited section measured. Temporal asymmetries helicities confirm irreducible 3D fields
Two magnetic flux ropes that collide and bounce have been characterized in the laboratory. We find screw pinch profiles include ion flow vi, field B, current density J, plasma pressure. The electron ve can be inferred, allowing evaluation of Hall J×B term a two fluid magnetohydrodynamic Ohm's Law. Flux are initially cylindrical mutually attracted compress each other, which distorts symmetry. Magnetic is created via ∇×ve×B induction Law where in-plane (perpendicular) shear parallel (along...
A large 3D data set has been assembled using the relaxation scaling experiment (RSX) device to study dynamics of flux ropes. In a series single rope experiments, we have measured induced eddy currents inside plasma that complicate evolution nominally simple current system. It is also likely nominal MHD force balance violated on ion inertial length scales. These phenomena appear irreducibly three dimensional.
In nature and many laboratory plasmas, a magnetic flux tube threaded by current or rope has footpoint at boundary. The driven kink mode is one of the fundamental ideal magnetohydrodynamic instabilities in plasmas. It an instability threshold that been found to strongly depend on boundary conditions (BCs). We provide theoretical model explain transition this dependence between nonline tied line conditions. evaluate parameters using experimentally measured plasma data, explicitly verify...
The AFRL Shiva Star capacitor bank (1300 microfarads, up to 120 kilovolts) operated typically with 4 5 megajoules of electrically stored energy, axial discharge currents 10 15 megamps, and current rise times approximately microseconds, has been used drive metal shell (solid liner) implosions in several geometries, including long cylindrical designs, which are suitable for compression magnetic fields multi-megagauss levels. Such imploding liners also compressing magnetized plasmas...
Detection of radioactive material at distances greater than the radiated particle range is an important goal with applications in areas such as national defense and disaster response. Here we demonstrate avalanche-breakdown-based remote detection a 3.6 mCi alpha-particle source stand-off distance 10 m, using 70 ps, long wave infrared (lambda=9.2 micron) CO2 laser pulses. This ~10X longer our previous results mid-IR laser. The primary method direct backscatter from microplasmas generated...
An active MHD diagnostic has been installed and operated on Alcator C-Mod to study Toroidal Alfven Eigenmodes (TAEs). The consists of two broadband amplifiers antennas which can excite stable modes in the TAE frequency range. plasma response this excitation is measured by existing magnetic fluctuation diagnostics. Analysis data provides information about frequencies damping rates as well mode structure. evolved since its first operation 2002, when it could only operate over a limited,...
The effect of realistic atmospheric conditions on mid-IR (λ = 3.9 µm) and long-wave-IR 10 laser-induced avalanche breakdown for the remote detection radioactive material is examined experimentally with propagation simulations. Our short-range in-lab laser experiments show a correlation between increasing turbulence level reduced number sites associated reduction in portion focal volume above threshold. Simulations through are excellent agreement these measurements provide code validation. We...
Abstract A broadband experimental study of Alfvén eigenmode (AE) damping and excitation examines both low- n high- AEs (0 < | 9) with a single diagnostic. Direct measurements the rate stable active MHD system, in conjunction analytic numerical calculation, indicate that AE stabilization Alcator C-Mod is largely due to radiative damping. are also regularly observed become unstable during ICRF heating above 3 MW. The most modes have moderate- around = −4, agreement common scaling k θ ρ fast...
Energetic particle physics is studied in Alcator C-Mod reactor relevant regimes with high density and equilibrated electron ion temperatures. Stable Alfvén eigenmodes are excited low-power active magnetohydrodynamic antennas the absence of a significant energetic tail to directly measure damping rate modes. toroidal eigenmode (TAE) rates between 0.5% < γ/Ω 4.5% have been observed diverted limited plasmas. destabilized high-power hydrogen minority cyclotron radio frequency (ICRF) heating...
Summary form only given. The Field-Reversed Configuration Heating Experiment (FRCHX) is a collaborative experiment between the Air Force Research Laboratory (AFRL) and Los Alamos National (LANL) to study high energy density laboratory plasma (HEDLP) phenomena, which encompass such topics as magneto-inertial fusion (MIF). In this experiment, field-reversed configuration (FRC) plasmas are formed via reversed-field theta pinch then translated into cylindrical aluminum shell (solid liner), where...