A5041343949- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Particle accelerators and beam dynamics
- Geomagnetism and Paleomagnetism Studies
- Superconducting Materials and Applications
- Laser-induced spectroscopy and plasma
- Laser-Plasma Interactions and Diagnostics
- Earthquake Detection and Analysis
- Ocean Waves and Remote Sensing
- Fusion materials and technologies
- Antenna Design and Analysis
- Gyrotron and Vacuum Electronics Research
- Magnetic Field Sensors Techniques
- Nuclear Physics and Applications
- Characterization and Applications of Magnetic Nanoparticles
- Space Satellite Systems and Control
- Spacecraft and Cryogenic Technologies
- Electric Motor Design and Analysis
- Astro and Planetary Science
- Electromagnetic Compatibility and Measurements
- Particle Accelerators and Free-Electron Lasers
- Fluid Dynamics and Turbulent Flows
- Electromagnetic Launch and Propulsion Technology
General Atomics (United States)
2021-2025
University of California, Los Angeles
2012-2022
Oak Ridge National Laboratory
2020
Fusion Academy
2020
Plasma Technology (United States)
2020
Fusion (United States)
2020
Lodestar Research Corporation (United States)
2020
UCLA Health
2018-2020
Los Alamos National Laboratory
2018
Planetary Science Institute
2016
Abstract The objectives of NSTX-U research are to reinforce the advantages STs while addressing challenges. To extend confinement physics low- A , high beta plasmas lower collisionality levels, understanding transport mechanisms that set performance and pedestal profiles is being advanced through gyrokinetic simulations, reduced model development, comparison NSTX experiment, as well improved simulation RF heating. develop stable non-inductive scenarios needed for steady-state operation,...
In 1991 a manuscript describing an instrument for studying magnetized plasmas was published in this journal. The Large Plasma Device (LAPD) upgraded 2001 and has become national user facility the study of basic plasma physics. upgrade as well diagnostics introduced since then significantly changed capabilities device. All references to machine still quote original RSI paper, which at time is not appropriate. work, properties updated LAPD are presented. strategy construction, available...
Abstract We report the first measurements of formation and structure a magnetized collisionless shock by laser‐driven magnetic piston in current‐free laboratory plasma. This new class experiments combines high‐energy laser system large plasma to transfer energy from plume ambient ions through coupling, until self‐sustained M A ∼ 2 magnetosonic separates piston. The is highly magnetized, current free, enough (17 m × 0.6 m) support Alfvén waves. Magnetic field evolution are consistent with...
One of the fundamental waves in magnetized plasmas is shear Alfvén wave. This wave responsible for rearranging current systems and, fact all low frequency currents are waves. It has become apparent that important a wide variety physical environments. Shear various forms have been topic experimental research more than fifteen years large plasma device (LAPD) at UCLA. The were first studied both kinetic and inertial regimes when excited by fluctuating with transverse dimension on order...
Whistler mode chorus emissions with a characteristic frequency chirp are important magnetospheric waves, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also scattering loss these into atmosphere. Here, we report on first laboratory experiment where whistler waves exhibiting fast chirping have been artificially produced using beam energetic launched cold plasma. Frequency chirps only observed narrow range plasma parameters, show strong...
A new frequency-stepped Doppler backscattering (DBS) system has been integrated into a real-time steerable electron cyclotron heating launcher to simultaneously probe local background turbulence (f < 10 MHz) and high-frequency (20–550 density fluctuations in the DIII-D tokamak. The allows for 2D steering (horizontally vertically) over wide angular ranges optimize location wavenumber response. vertical can be optimized during discharge real time. DBS employs programmable frequency...
Chorus-like whistler-mode waves that are known to play a fundamental role in driving radiation-belt dynamics excited on the Large Plasma Device by injection of helical electron beam into cold plasma. The mode structure whistler wave is identified using phase-correlation technique showing through combination Landau resonance, cyclotron resonance and anomalous resonance. dominant quasi-parallel propagating, whereas modes propagate at oblique angles close cone. An analysis linear growth rates...
Abstract As part of ITPA-Integrated Operational Scenario activities, this contribution reviews recent experimental characterizations radio-frequency (RF)-induced scrape-off layer (SOL) modifications various tokamaks worldwide and the LArge Plasma Device at UCLA. The phenomenology, as observed using a large variety measurement techniques, is consistent with expectations from RF sheath rectification. Emphasis then put on complex three-dimensional (3D) spatial patterns RF–SOL interaction, in...
Two and three magnetic flux ropes are created studied in a well-diagnosed laboratory experiment. The twisted helical bundles of field lines rotate collide with each other over time. In the two rope case, reverse current layers indicative reconnection observed. Using high spatial temporal resolution three-dimensional volume data set both cases, quasi-separatrix (QSLs) identified field. Originally developed context solar reconnection, QSLs thought to be preferred sites for reconnection. This...
The dynamics of magnetic reconnection is investigated in a laboratory experiment consisting two flux ropes, with currents slightly above the threshold for kink instability. evolution features periodic bursts reconnection. To diagnose this complex evolution, volumetric three-dimensional data were acquired both and electric fields, allowing key field-line mapping quantities to be directly evaluated first time experimental data. ropes interact by rotating about each other periodically bouncing...
Magnetic flux ropes immersed in a uniform magnetoplasma are observed to twist about themselves, writhe each other and rotate central axis. They kink unstable smash into one another as they move. Each collision results magnetic field line reconnection the generation of quasi-separatrix layer. Three-dimensional lines computed by conditionally averaging data using correlation techniques. Conditional is possible for only number rotation cycles motion becomes chaotic. The permutation entropy can...
The electron beam-plasma system is ubiquitous in the space plasma environment. Here, using a Darwin particle-in-cell method, excitation of electrostatic and whistler instabilities by gyrating beam studied support recent laboratory experiments. It assumed that total frequency (ωpe) larger than cyclotron (Ωe). fast-growing beam-mode waves saturate few oscillations slowing down relaxing parallel to background magnetic field. Upon their saturation, finite amplitude can resonate with tail thermal...
The interaction of a laser-driven super-Alfvénic magnetic piston with large, preformed magnetized ambient plasma has been studied by utilizing unique experimental platform that couples the Raptor kJ-class laser system [Niemann et al., J. Instrum. 7, P03010 (2012)] to Large Plasma Device [Gekelman Rev. Sci. 62, 2875 (1991)] at University California, Los Angeles. This provides conditions relevance space and astrophysical collisionless shocks and, in particular, allows detailed study...
Resonant interactions between energetic electrons and whistler mode waves are an essential ingredient in the space environment, particular controlling dynamic variability of Earth's natural radiation belts, which is a topic extreme interest at moment. Although theory describing resonant wave-particle interaction has been present for several decades, it not hitherto tested controlled laboratory setting. In Letter we report on first experiment to directly detect pitch angle scattering...
Helicon current drive (CD), also called fast wave CD in the lower hybrid range of frequencies, has long been regarded as a promising tool for reactor grade plasmas.A newly installed MW-level system at DIII-D will be first test this technology reactor-relevant plasmas, sense that full single-pass absorption is expected.A 30-module traveling antenna and optimized in-vessel early 2020.The linear electromagnetic characteristics unloaded module array have extensively tested both on bench vessel...
A set of experiments using controlled, skin depth-sized plasma pressure filaments in close proximity have been carried out a large linear magnetized device. Two- and three-filament configurations used to determine the scale cross field nonlinear interaction. When are separated by distance approximately five times size single filament or less, significant transfer charge energy occurs, leading generation inter-filament electric fields. This has effect rotating influencing merging dynamics....
Helicon waves are thought to be promising in various tokamaks, such as DIII-D, because they can penetrate reactor-grade high-density cores and drive the off-axis current with higher efficiency. In frequency regime ∼ 476 MHz, both slow electrostatic fast electromagnetic helicon coexist DIII-D. If antenna parasitically excites mode, these propagate along magnetic field line into scrape-off layer (SOL). Although importance of misalignment Faraday screen electron density SOL on excitation...
An experiment in a linear device, the Large Plasma Device, is used to study sheaths caused by an actively powered radio frequency (rf) antenna. The rf antenna consists of single current strap recessed inside copper box enclosure without Faraday screen. A large increase plasma potential was observed along magnetic field lines that connect limiter. electric from spatial variation rectified generated...
A LaB6 thermionic emitter of annular shape is used in the Large Plasma Device at University California, Los Angeles to create off-axis heating conditions for various transport studies. Since biased relative a distant anode, which many collision lengths away, entire magnetized plasma develops self-consistent, potential structure that simultaneously generates transverse and axial flows with shear. This study uses swept Langmuir probe techniques Mach probes map flow patterns their dependence on...
Whistler mode chorus emissions with a characteristic frequency chirp are important magnetospheric waves, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also scattering loss these into atmosphere. A laboratory experiment (Van Compernolle et al 2015 Phys. Rev. Lett. 114 245002, An 2016 Geophys. Res. Lett.) in large plasma device at UCLA was designed closely mimic scaled parameters observed inner magnetosphere, shed light on excitation discrete...
A high-level design study for a new experimental tokamak shows that advances in fusion science and engineering can be leveraged to narrow the gaps energy confinement exhaust power handling remain between present devices future pilot plant (FPP). This potential U.S. facility, an Exhaust Confinement Integration Tokamak Experiment (EXCITE), will access operational space close projected FPP performance regime via compact, high-field, high-power-density approach utilizes advanced scenarios...
Flux ropes are ubiquitous in space and solar plasmas. Multiple adjacent flux commonly observed both the corona earth's magnetotail. The interaction of is often dynamic can lead to magnetic reconnection. In this paper, three studied a low β background laboratory magnetoplasma. structure rope produced by poloidal field field-aligned finite sized current which adds guide creates typical helical line structure. Each produces fields on order few percent field. Volumetric data were acquired...
A portable lanthanum hexaboride (LaB6) cathode has been developed for use in the LArge Plasma Device (LAPD) at UCLA. The LaB6 can be used as a tool many different studies experimental plasma physics. To date, source of with hot dense core transport and diagnostics development, gradient driven modes, shear Alfvén waves, interacting current channels reconnection experiments. is capable higher discharge densities than main barium oxide coated LAPD therefore able to produce plasmas electron...
Abstract The plasma resistivity was evaluated in an experiment on the collision of two magnetic flux ropes. Whenever ropes collide, some energy is lost as a result reconnection. Volumetric data, which all relevant time-varying quantities were recorded detail, are presented. Ohm’s law shown to be nonlocal and cannot used evaluate resistivity. instead calculated using AC Kubo anomalously high certain regions space.