A5044700658- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Nuclear reactor physics and engineering
- Particle Accelerators and Free-Electron Lasers
- Atomic and Subatomic Physics Research
- Spacecraft and Cryogenic Technologies
- Nuclear Materials and Properties
- Physics of Superconductivity and Magnetism
- Particle Detector Development and Performance
- Electromagnetic Launch and Propulsion Technology
- Nuclear Engineering Thermal-Hydraulics
- Magnetic Field Sensors Techniques
- Laser-induced spectroscopy and plasma
- Nuclear Physics and Applications
- Dust and Plasma Wave Phenomena
- Frequency Control in Power Systems
- Distributed and Parallel Computing Systems
- Semiconductor materials and devices
- Metal and Thin Film Mechanics
Princeton Plasma Physics Laboratory
2016-2025
Princeton University
2009-2024
Culham Science Centre
2014
Lawrence Livermore National Laboratory
2001-2013
Johns Hopkins University
2001-2011
Columbia University
2003-2008
University of Washington
2001-2007
Oak Ridge National Laboratory
2003-2007
University of Baltimore
2006-2007
Nova Photonics (United States)
2006-2007
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,...
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...
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.
Reduction or elimination of edge localized modes (ELMs) while maintaining high confinement is essential for future fusion devices, e.g., the ITER. An ELM-free regime was recently obtained in National Spherical Torus Experiment, following lithium (Li) evaporation onto plasma-facing components. Edge stability calculations indicate that pre-Li discharges were unstable to low-$n$ peeling ballooning modes, broader pressure profiles stabilized post-Li discharges. Normalized energy increased by 50%...
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....
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,...
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%)...
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 sensitivity of tokamak plasmas to very small deviations from the axisymmetry magnetic field |deltaB/B| approximately 10{-4} is well known. What was not understood until recently importance perturbation plasma equilibrium in assessing effects externally produced asymmetries field, even far a stability limit. DIII-D and NSTX experiments find that when deleterious are mitigated, external asymmetric often made stronger had an increased interaction with unperturbed equilibrium. This Letter...
Large Type-I edge-localized mode (ELM) heat pulses may limit the life of divertor targets in a burning plasma. Recent experiments show that pitch-resonant nonaxisymmetric magnetic perturbations plasma edge 0.0005 or less main field offer useful solution, but there is little room presently designed ITER for even small perturbation coils. We present proposed coil requirements ELM suppression, derived primarily from DIII-D suppression experiments. by calculated examples large arrays coils (e.g....
High-speed high-spatial-resolution data obtained by the gas puff imaging (GPI) diagnostic on National Spherical Torus Experiment [M. Ono, M.G. Bell, R.E. Bell et al. Plasma Phys. Control. Fusion 45, A335 (2003).] is analyzed and interpreted in light of recent theoretical models for electrostatic edge turbulence blob propagation. The experiment described terms regimes that predict different dependencies radial velocity convection. Using GPI data, atomic physics analysis, tracking a restricted...
Recent experiments (Synakowski et al 2004 Nucl. Fusion 43 1648, Lloyd Plasma Phys. Control. 46 B477) on the Spherical Tokamak (or Torus, ST) (Peng 2000 Plasmas 7 1681) have discovered robust plasma conditions, easing shaping, stability limits, energy confinement, self-driven current and sustainment. This progress has encouraged an update of conditions engineering a Component Test Facility (CTF), (Cheng 1998 Eng. Des. 38 219) which is very valuable step in development practical fusion energy....
Small nonaxisymmetric perturbations of the magnetic field can greatly change performance tokamaks through nonambipolar transport. A number theories have been developed, but predictions were not consistent with experimental observations in tokamaks. This Letter provides a resolution, generalized analytic treatment It is shown that discrepancy between theory and experiment be reduced by two effects: (1) small fraction trapped particles for which bounce precession rates resonate; (2) variation...
The resistive-wall mode is actively stabilized in the National Spherical Torus Experiment high-beta plasmas rotating significantly below critical rotation speed for passive stability and range predicted International Thermonuclear Experimental Reactor. Variation of feedback stabilization parameters shows excitation or suppression. Stabilization toroidal number unity did not lead to instability two. can become unstable by deforming poloidally, an important consideration system design.
Stabilizing modes that limit plasma beta and reduce their deleterious effect on rotation are key goals for the efficient operation of a fusion reactor. Passive stabilization active control global kink/ballooning resistive wall (RWMs) have been demonstrated NSTX research is now advancing towards understanding physics reliably maintaining high confident extrapolation to ITER component test facility based spherical torus. Active n = 1 experiments with an expanded sensor set, combined low levels...
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...
Liquid metal plasma-facing components (PFCs) have been proposed as a means of solving several problems facing the creation economically viable fusion power reactors. To date, few demonstrations exist this approach in diverted tokamak and we here provide an overview such work on National Spherical Torus Experiment (NSTX). The Lithium Divertor (LLD) was installed operated for 2010 run campaign using evaporated coatings filling method. LLD consisted copper-backed structure with porous...
A potentially attractive next-step towards fusion commercialization is a pilot plant, i.e. device ultimately capable of small net electricity production in as compact facility possible and configuration scalable to full-size power plant. key capability for pilot-plant programme the high neutron fluence enabling nuclear science technology (FNST) research. It found that physics assumptions between those assumed ITER nth-of-a-kind it provide FNST-relevant wall loading devices. Thus, may be...
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...