A5015424431- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Laser-Plasma Interactions and Diagnostics
- Nuclear reactor physics and engineering
- Geomagnetism and Paleomagnetism Studies
- Atomic and Subatomic Physics Research
- Particle Accelerators and Free-Electron Lasers
- Metal and Thin Film Mechanics
- Meteorological Phenomena and Simulations
- Dust and Plasma Wave Phenomena
- Earthquake Detection and Analysis
- Particle Detector Development and Performance
- Atomic and Molecular Physics
- Fluid Dynamics and Turbulent Flows
- Nuclear Physics and Applications
- Radiation Effects in Electronics
- Nuclear and radioactivity studies
- Distributed and Parallel Computing Systems
- Silicon and Solar Cell Technologies
- Spectroscopy and Laser Applications
Princeton Plasma Physics Laboratory
2016-2025
Princeton University
2013-2024
Chalmers University of Technology
2021
Lehigh University
2021
University of California, San Diego
2003-2013
University of Wisconsin–Madison
2013
University of Colorado Boulder
2006-2010
University of Warwick
2010
University of Washington
2001-2007
Oak Ridge National Laboratory
1990-2007
While the results of early work on density limit in tokamaks from ORMAK and DITE groups have been useful over years, recent experiments requirements for extrapolation to future prompted a new look at this subject. There are many physical processes which attainable densities tokamak plasmas. These include: (1) radiation low Z impurities, convection, charge exchange other losses plasma edge; (2) or high impurities core; (3) deterioration particle confinement (4) inadequate fuelling, often...
On the basis of an analysis ITER L-mode energy confinement database, two new scaling expressions for tokamak are proposed, namely a power law and offset-linear scaling. The indicates that present multiplicity time τE in tokamaks (Goldston, Kaye, Odajima-Shimomura, Rebut-Lallia, etc.) is due both to lack variation key parameter combination fs = 0.32 R a−0.75 k0.5 ∼ A a0.25k0.5, variations dependence on physical parameters among different database. By combining multiples another factor, fq...
Strong magnetohydrodynamic activity has been observed in PDX neutral-beam-heated discharges. It occurs for ${\ensuremath{\beta}}_{T}q>~0.045$ and is associated with a significant loss of fast ions drop neutron emission. As much as 20%-40% the beam heating power may be lost. The instability repetitive bursts oscillations \ensuremath{\le} 1 msec duration at 1-6-msec intervals. dubbed "fishbone instability" from its characteristic signature on Mirnov coils.
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,...
Abstract Progress in physics understanding and theoretical model development of plasma transport confinement (TC) the ITPA TC Topical Group since publication ITER Physics Basis (IPB) document (Doyle et al 2007 Nucl. Fusion 47 S18) was summarized focusing on contributions to burning prediction control. This paper provides a general streamlined overview advances that were mainly led by joint experiments activities for last 15 years (see JEX/JA table appendix). starts with scientific strategy...
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...
The two-dimensional radial vs poloidal structure and motion of edge turbulence in the National Spherical Torus Experiment (NSTX) were measured using high-speed imaging visible light emission from a localized neutral gas puff. Edge images are shown analysed for Ohmic, L- H-mode plasma conditions. often show regions strong known as 'blobs', which move both poloidally radially at typical speed ≈105 cm s−1, sometimes spatially periodic features.
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...
Dissipation of plasma toroidal angular momentum is observed in the National Spherical Torus Experiment due to applied nonaxisymmetric magnetic fields and their plasma-induced increase by resonant field amplification resistive wall mode destabilization. The measured decrease profile compared calculations nonresonant drag torque based on theory neoclassical viscosity. Quantitative agreement between experiment found when effect toroidally trapped particles included.
A total of 677 representative discharges from seven neutral-beam-heated tokamaks have been used to study the parametric scaling global energy confinement time. Contributions this data base were Asdex, DITE, D-III, ISX-B, PDX, PLT and TFR, taken results gettered, L-mode type discharges. Assuming a power law dependence τE on discharge parameters κ, Ip, Bt, e Ptot, R. standard multiple linear regression techniques in two steps determine scaling. The indicate that are well described by .
National Spherical Torus Experiment [which M. Ono et al., Nucl. Fusion 40, 557 (2000)] high-power divertor plasma experiments have shown, for the first time, that benefits from lithium coatings applied to facing components found previously in limited plasmas can occur also diverted configurations. Lithium were with pellets injected into helium discharges, and an oven directed a collimated stream of vapor toward graphite tiles lower center stack divertor. depositions few milligrams 1g been...
Abstract A fusion nuclear science facility (FNSF) could play an important role in the development of energy by providing environment needed to develop materials and components. The spherical torus/tokamak (ST) is a leading candidate for FNSF due its potentially high neutron wall loading modular configuration. key consideration choice configuration range achievable missions as function device size. Possible include: fluence, demonstrating tritium self-sufficiency, electrical self-sufficiency....
This Letter presents nonlinear gyrokinetic simulations of microtearing mode turbulence. The include collisional and electromagnetic effects use experimental parameters from a high-β discharge in the National Spherical Torus Experiment. predicted electron thermal transport is comparable to that given by analysis, it dominated contribution electrons free-streaming along resulting stochastic magnetic field line trajectories. Experimental values flow shear can significantly reduce transport.
Abstract Lithium wall coatings have been shown to reduce recycling, suppress edge-localized modes (ELMs), and improve energy confinement in the National Spherical Torus Experiment (NSTX). Here we document effect of gradually increasing lithium on discharge characteristics, with reference ELMy discharges obtained boronized, i.e. non-lithiated conditions. We observed a continuous but not quite monotonic reduction recycling improvement confinement, gradual alteration edge plasma profiles,...
Abstract Ion temperatures of over 100 million degrees Kelvin (8.6 keV) have been produced in the ST40 compact high-field spherical tokamak (ST). excess 5 keV not previously reached any ST and only obtained much larger devices with substantially more plasma heating power. The corresponding fusion triple product is calculated to be <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>n</mml:mi> <mml:mi>i</mml:mi> <mml:mn>0</mml:mn>...
Abstract A theoretical model is presented that for the first time matches experimental measurements of pedestal width-height Diallo scaling in low-aspect-ratio high- β tokamak NSTX. Combining linear gyrokinetics with self-consistent equilibrium variation, kinetic-ballooning, rather than ideal-ballooning plasma instability, shown to limit achievable confinement spherical pedestals. Simulations are used find novel Gyrokinetic Critical Pedestal constraint, which determines steepest pressure...
Research in NSTX has been conducted to establish spherical torus plasmas be used for high β, auxiliary heated experiments. This device a major radius R0 = 0.86 m and midplane halfwidth of 0.7 m. It operated with toroidal magnetic field B0 ⩽ 0.3 T Ip 1.0 MA. The evolution the plasma equilibrium is analysed between discharges an automated version EFIT code. Limiter, double null lower single diverted configurations have sustained several energy confinement times. stored reached 92 kJ (βt 17.8%)...
This special topic describes the contents of an L mode database that has been compiled with data from Alcator C-Mod, ASDEX, DIII, DIII-D, FTU, JET, JFT-2M, JT-60, PBX-M, PDX, T-10, TEXTOR, TFTR and Tore Supra. The consists a total 2938 entries, 1881 which are in phase while 922 ohmically heated only (ohmic). Each entry contains up to 95 descriptive parameters, including global kinetic information, machine conditioning configuration. presents description variables contained therein, it also...
The National Spherical Torus Experiment (NSTX) has demonstrated the advantages of low aspect ratio geometry in accessing high toroidal and normalized plasma beta, βN ≡ 108⟨βt⟩ aB0/Ip. Experiments have reached βt = 39% 7.2 through boundary profile optimization. High plasmas can exceed ideal no-wall stability limit, βNno−wall, for periods much greater than wall eddy current decay time. Resistive mode (RWM) physics is studied to understand stabilization these plasmas. spectrum unstable RWMs...
The ITER Threshold Database, which at present comprises data from nine divertor tokamaks, is described. main results are presented and discussed. properties dependences of the power threshold in individual devices reviewed. In particular, analysis shows a rather general linear dependence on magnetic field, but non-monotonic density that varies device to device. Investigation combined database suggests P thres approximately=0.3n e B T 2.5 reasonable agreement with data. This expression yields...
The effects of toroidal and poloidal flows on the equilibrium tokamak plasmas are numerically investigated using code FLOW. is used to determine changes in profiles induced by large NSTX-like equilibria [with NSTX being National Spherical Torus Experiment, M. Ono, S.M. Kaye, Y.-K.M. Peng et al., Nucl. Fusion 40, 557 (2000)] where exceeding sound speed lead a considerable outward shift plasma. also study flow when velocity profile varies from subsonic supersonic with respect speed. It found...
Experiments in the National Spherical Torus Experiment (NSTX) have shown beneficial effects on performance of divertor plasmas as a result applying lithium coatings graphite and carbon-fiber-composite plasma-facing components. These mostly been applied by pair evaporators mounted at top vacuum vessel which inject collimated streams vapor toward lower divertor. In neutral beam injection (NBI)-heated deuterium H-mode run immediately after application lithium, modifications included decreases...
The NSTX operates at low aspect ratio (R/a ∼ 1.3) and high beta (up to 40%), allowing tests of global confinement local transport properties that have been established from higher devices. plasmas are heated by up 7 MW deuterium neutral beams with preferential electron heating as expected for ITER. Confinement scaling studies indicate a strong BT dependence, current dependence is weaker than observed ratio. Dimensionless experiments increase in decreasing collisionality weak degradation...
The low-aspect ratio, low magnetic field and wide range of plasma beta NSTX plasmas provide new insight into the origins effects errors. An extensive array sensors has been used to analyse error fields, measure error-field amplification detect resistive wall modes (RWMs) in real time. measured normalized threshold for onset locked shows a linear scaling with density, weak inverse dependence on toroidal positive shear. These results extrapolate favourable ITER. For these low-beta locked-mode...