A5053911915- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Laser-induced spectroscopy and plasma
- Nuclear reactor physics and engineering
- Geomagnetism and Paleomagnetism Studies
- Advanced Data Storage Technologies
- Nuclear Physics and Applications
- French Literature and Criticism
- Atomic and Subatomic Physics Research
- Atomic and Molecular Physics
- Electrostatic Discharge in Electronics
- French Historical and Cultural Studies
- Metal and Thin Film Mechanics
- Fluid Dynamics and Turbulent Flows
- Natural Language Processing Techniques
- Physics of Superconductivity and Magnetism
- Advancements in Semiconductor Devices and Circuit Design
- Dust and Plasma Wave Phenomena
- Lattice Boltzmann Simulation Studies
Sandia National Laboratories California
2024
NOAA National Centers for Environmental Information
2022-2024
Energetics (United States)
2001-2023
University of Washington
2013-2023
Lawrence Livermore National Laboratory
2006-2023
University of California, San Diego
2006-2023
American Institute of Aeronautics and Astronautics
2013-2022
Voss Scientific (United States)
2019
University of Wisconsin–Madison
1982-2017
University of Washington Applied Physics Laboratory
1993-2017
The National Spherical Torus Experiment (NSTX) is being built at Princeton Plasma Physics Laboratory to test the fusion physics principles for spherical torus concept MA level. NSTX nominal plasma parameters are R0 = 85 cm, a 67 R/a ⩾ 1.26, Bt 3 kG, Ip 1 MA, q95 14, elongation κ ⩽ 2.2, triangularity δ 0.5 and pulse length of up 5 s. heating/current drive tools high harmonic fast wave (6 MW, s), neutral beam injection (5 80 keV, s) coaxial helicity injection. Theoretical calculations predict...
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...
Abstract The spherical tokamak (ST) is a leading candidate for Fusion Nuclear Science Facility (FNSF) due to its compact size and modular configuration. National Spherical Torus eXperiment (NSTX) MA-class ST facility in the US actively developing physics basis an ST-based FNSF. In plasma transport research, experiments exhibit strong (nearly inverse) scaling of normalized confinement with collisionality, if this trend holds at low high fusion neutron fluences could be achievable very...
A suite of gridded daily satellite (CMORPH, IMERG) and in-situ (NClimGrid) precipitation datasets are used to compute a near-real time standardized index (SPI) over various scales (from 1-month 36-month). Over CONUS, the Standardized Precipitation Evapotranspiration Index (SPEI) is also computed using potential evapotranspiration (PET) derived from NClimGrid temperature estimates. The drought indices: CMORPH-SPI (global; 1998-present; 0.25x0.25deg.), IMERG-SPI 2000-present; 0.1x0.1deg.),...
The sheared-flow stabilized $Z$-pinch has demonstrated long-lived plasmas with fusion-relevant parameters. This Letter presents the first experimental results demonstrating sustained, quasi-steady-state neutron production from Fusion Experiment (FuZE), operated a mixture of 20% deuterium/80% hydrogen by volume. Neutron emissions lasting approximately $5~\mu$s are reproducibly observed pinch currents $200$ kA during an $16~\mu$s period plasma quiescence. average yield is estimated to be...
AbstractThe mission of the National Spherical Torus Experiment (NSTX) is to prove principles spherical torus physics by producing high-βt plasmas that are noninductively sustained and whose current profiles in steady state. The NSTX will be one first ultralow-aspect-ratio tori (R/a ≤ 1.3) operate at high power (Pinput up 11 MW) produce (25 40%), low-collisionality, high-bootstrap-fraction (≤70%) discharges. Both radio-frequency neutral beam heating drive employed. Built into sufficient...
Theoretical studies have predicted that the Z-pinch can be stabilized with a sufficiently sheared axial flow [U. Shumlak and C. W. Hartman, Phys. Rev. Lett. 75, 3285 (1995)]. A experiment is designed to generate plasma which contains large flow. Magnetic fluctuations velocity profiles in pinch are measured. Experimental results show stable period over 700 times expected instability growth time static Z-pinch. The experimentally measured shear greater than theoretical threshold during...
The ZaP and ZaP-HD Flow Z-pinch experiments at the University of Washington have successfully demonstrated that sheared plasma flows can be used as a stabilization mechanism over range parameters has not previously been accessible to long-lived configurations. is effective even when column compressed small radii, producing predicted increases in magnetic field electron temperature. flow shear value, extent, duration are shown consistent with theoretical models viscosity, which places design...
The major objective of the National Spherical Torus Experiment (NSTX) is to understand basic toroidal confinement physics at low aspect ratio and high βT in order advance spherical torus (ST) concept. In do this, NSTX utilizes up 7.5 MW neutral beam injection, 6 harmonic fast waves (HHFWs), it operates with plasma currents 1.5 MA elongations 2.6 a field 0.45 T. New facility, diagnostic modelling capabilities developed over past two years have enabled research team make significant progress...
A high-density magnetized plasma is seen to heat small diameter tungsten wire probes electron emission. The use of these self-emissive determine the potential in a tandem mirror investigated. simplified model presented and comparison made with conventional emissive probe behavior.
Transient coaxial helicity injection (CHI) started discharges in the National Spherical Torus Experiment (NSTX) have attained peak currents up to 300 kA and when coupled induction, it has produced 200 additional current over inductive-only operation. CHI NSTX shown be energetically quite efficient, producing a plasma of about 10 A/J capacitor bank energy. In addition, for first time, CHI-produced toroidal that couples induction continues increase with energy supplied by power supply at...
We demonstrate the application of Dynamic Mode Decomposition (DMD) for diagnostic analysis nonlinear dynamics a magnetized plasma in resistive magnetohydrodynamics. The DMD method is an ideal spatio-temporal matrix decomposition that correlates spatial features computational or experimental data while simultaneously associating activity with periodic temporal behavior. can produce low-rank, reduced order surrogate models be used to reconstruct state system high fidelity. This allows...
The sheared-flow-stabilized Z pinch concept has been studied extensively and is able to produce fusion-relevant plasma parameters along with neutron production over several microseconds. We present here elevated electron temperature results spatially temporally coincident the source. An optical Thomson scattering apparatus designed for FuZE device measures temperatures in range of 1–3 keV on axis device, 20 cm downstream nose cone. 17-fiber system radial profiles temperature. Scanning laser...
The stabilizing effect of a sheared axial flow on the m=1 kink instability in Z pinches has been studied numerically with linearized ideal magnetohydrodynamic model to reveal that stabilizes mode when shear exceeds threshold. is investigated ZaP (Z-Pinch) Flow Z-pinch experiment at University Washington. An axially flowing pinch generated 1 m coaxial accelerator coupled assembly chamber. plasma assembles into 50 cm long radius approximately cm. azimuthal array surface mounted magnetic probes...
The first successful results on the transfer of a coaxial helicity injection (CHI) produced discharge to inductive operation are reported. CHI-assisted plasma startup is more robust than only operation. After hand off for operation, initial 90 kA CHI-produced current drops 40 kA, then ramps up 170 using 30 mV s, 30% higher that by induction alone. These significant performance enhancing were obtained HIT-II spherical torus experiment (major/minor radius 0.3/0.2 m).
The ZaP Flow Z-Pinch project is experimentally studying the effect of sheared flows on Z-pinch stability. It has been shown theoretically that when dVz∕dr exceeds 0.1kVA kink (m=1) mode stabilized. [U. Shumlak and C. W. Hartman, Phys. Rev. Lett. 75, 3285 (1995).] Z pinches with an embedded axial flow are formed in a coaxial accelerator coupled 1m assembly region. Long-lived, quiescent generated throughout first half cycle current. During initial plasma acceleration phase, motion current...
The potential profiles of an expanding plasma have been measured experimentally. are shown to be self-similar.
The stabilizing effect of a sheared axial flow is investigated in the ZaP Z-pinch experiment at University Washington. Long-lived, hydrogen plasmas are generated that 1 m long with an approximately 10 mm radius and exhibit gross stability for many Alfvén transit times. Large magnetic fluctuations occur during pinch assembly, after which amplitude frequency diminish. This stable behaviour continues extended quiescent period. At end period, fluctuation levels increase magnitude frequency....
We report the first optical Thomson scattering measurements inside a high electron temperature (≳1 keV) and moderate density (mid 1016 cm−3) plasma. This diagnostic has been built to provide critical plasma parameters, such as density, for Advanced Research Projects Agency-Energy-supported fusion-energy concepts. It uses an 8 J laser at 532 nm in 1.5 ns measure frequency feature of profile 17 locations along probe axis. is able from 5 × 1017 cm−3 several 1019 temperatures tens eV keV. Here,...
Zap Energy is a private fusion energy company developing the sheared-flow-stabilized (SFS) Z-pinch concept for commercial production. Spun out from University of Washington, these experimental and computational efforts have resulted in devices with quasi-steady DD yields above 109 per pulse. These support scaling toward breakeven on existing as well beyond to commercially relevant engineering gains. This article discusses strategy behind Zap's development path, which derived directly...
A major research goal of the national spherical torus experiment is establishing long-pulse, high beta, confinement operation and its physics basis. This has been enabled by facility capabilities developed during 2001 2002, including neutral beam (up to 7 MW) harmonic fast wave (HHFW) heating 6 MW), toroidal fields up kG, plasma currents 1.5 MA, flexible shape control, wall preparation techniques. These have generation plasmas with 35%. Normalized beta values often exceed no-wall limit,...
The main aim of the National Spherical Torus Experiment (NSTX) is to establish fusion physics principles spherical torus (ST) concept. NSTX device began plasma operations in February 1999 and current Ip was successfully brought up design value 1 MA on 14 December 1999. planned shaping parameters, elongation κ = 1.6-2.2 triangularity δ 0.2-0.4, were achieved inner wall limited, single null double diverted configurations. coaxial helicity injection (CHI) high harmonic fast wave (HHFW)...
A method of coaxial helicity injection has successfully produced a closed flux current without the use central solenoid in NSTX device, on size scale closer to spherical torus reactor, for proof-of-principle demonstration this concept. For first time, remarkable 60 times multiplication factor was achieved. Grad-Shafranov plasma equilibrium reconstructions are used verify existence current. In some discharges generated persists surprisingly long time approximately 400 ms.
A spheromak is formed for the first time using a new steady state inductive helicity injection method. Using two injectors with odd symmetry and oscillating at 5.8 kHz, even sustained through nonlinear relaxation. about 13 kA of toroidal current 3 MW power. This much lower power threshold production than required electrode-based injection. Internal magnetic probe data, including oscillations driven by injectors, agree plasma being in Taylor state. The agreement remarkable considering only...
Abstract A mechanism for steady inductive helicity injection (SIHI) current drive has been discovered where the driving fluctuations are not generated by plasma but rather imposed injectors. Sheared flow of electron fluid distorts to current. The model accurately predicts time dependent toroidal current, injector impedance scaling, and profile produced in HIT-SI experiment. These results show that a stable equilibrium can be efficiently sustained with can, principle, controlled. Both large...