A5083111426- Magnetic confinement fusion research
- Fusion materials and technologies
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Nuclear reactor physics and engineering
- Engineering Applied Research
- Nuclear Materials and Properties
- Solar and Space Plasma Dynamics
- Atomic and Subatomic Physics Research
- High-Energy Particle Collisions Research
- Nuclear Physics and Applications
- Gyrotron and Vacuum Electronics Research
- Electromagnetic Launch and Propulsion Technology
- Dust and Plasma Wave Phenomena
- High-pressure geophysics and materials
- Fluid Dynamics and Turbulent Flows
- Advanced Sensor Technologies Research
- Physics of Superconductivity and Magnetism
- Nuclear Engineering Thermal-Hydraulics
- Particle Accelerators and Free-Electron Lasers
- Geomagnetism and Paleomagnetism Studies
- Dynamics and Control of Mechanical Systems
Princeton Plasma Physics Laboratory
1991-2024
ITER
2013-2022
Institut Méditerranéen d’Océanologie
2019
Max Planck Society
2017
Max Planck Institute for Plasma Physics
2017
Japan External Trade Organization
2014
Japan Atomic Energy Agency
2007-2013
Plasma Technology (United States)
2000-2010
Fusion Academy
2000-2010
Fusion (United States)
1998-2010
The understanding and predictive capability of transport physics plasma confinement is reviewed from the perspective achieving reactor-scale burning plasmas in ITER tokamak, for both core edge regions. Very considerable progress has been made understanding, controlling predicting tokamak across a wide variety conditions regimes since publication Physics Basis (IPB) document (1999 Nucl. Fusion 39 2137–2664). Major areas considered here follow. (1) Substantial improvement content, reliability...
In JET, both high density and low-q operation are limited by disruptions. The limit disruptions caused initially impurity radiation. This causes a contraction of the plasma temperature profile leads to an MHD unstable configuration. There is evidence magnetic island formation resulting in minor After several disruptions, major disruption with rapid energy quench occurs. event takes place two stages. first stage there loss from central region. second more drop very low temperature, apparently...
Early operation of the Alcator-C-MOD tokamak [I.H. Hutchinson, Proceedings IEEE 13th Symposium on Fusion Engineering, Knoxville, TN, edited by M. Lubell, Nestor, and S. Vaughan (Institute Electrical Electronic Engineers, New York, 1990), Vol. 1, p. 13] is surveyed. Reliable operation, with plasma current up to 1 MA, has been obtained, despite massive conducting superstructure associated error fields. However, vertical disruptions are not slowed long vessel time constant. With pellet fueling,...
An overview of the present status research toward final design ITER disruption mitigation system (DMS) is given. The DMS based on massive injection impurities, in order to radiate plasma stored energy and mitigate potentially damaging effects disruptions. this will be extremely challenging due many physics engineering constraints such as limitations port access amount species injected impurities. Additionally, questions relevant remain unsolved mechanisms for mixing assimilation impurities...
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...
Experiments in the JET tokamak with additional heating power (ion cyclotron resonance and/or neutral beam injection) above 5 MW show that plasma can undergo a transition to new regime. In this regime, sawtooth instability is suppressed for periods up 1.6 s and level of long-wavelength, coherent MHD activity very low. An improvement global energy confinement time 20% observed. Possible mechanisms stabilization m=1 implications near-ignition regime are discussed.Received 26 May...
A series of experiments, examining the confinement properties ion cyclotron range frequencies (ICRF) heated H mode plasmas, has been carried out on Alcator C-Mod tokamak. is a compact tokamak that operates at high particle, power and current densities toroidal fields up to 8 T. Under these conditions plasma essentially thermal with very little contribution stored energy from energetic ions (typically no more than 5%) Ti~Te. Most data were taken machine in single null `closed' divertor...
Regimes of high-confinement mode have been studied in the Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. with no edge localized modes (ELM-free) compared detail to a new regime, enhanced Dα (EDA). EDA discharges only slightly lower energy confinement than comparable ELM-free ones, but show markedly reduced impurity confinement. Thus do not accumulate impurities and typically fraction radiated power. The gradients seem be relaxed by continuous process rather an...
In the Joint European Torus ablation of injected pellets produces a striking resonance effect when reach surfaces with q values 1 and (3/2. Subsequently, structures mode numbers m=1,n=1 m=3,n=2 are observed soft-x-ray cameras for up to 2 s as compact snakelike perturbations. These structures, which persist through several sawtooth collapses, give information on radii q=1 q=(3/2 q-profile evolution. The observations can be explained by formation magnetic islands.
The object of this review is to summarize the achievements research on Alcator C-Mod tokamak [Hutchinson et al., Phys. Plasmas 1, 1511 (1994) and Marmar, Fusion Sci. Technol. 51, 261 (2007)] place that in context quest for practical fusion energy. a compact, high-field tokamak, whose unique design operating parameters have produced wealth new important results since it began operation 1993, contributing data extends tests critical physical models into parameter ranges regimes. Using only...
Wall conditioning in the Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire et al., Phys. Plasmas 2, 2176 (1995)] by injection of lithium pellets into plasma has resulted large improvements deuterium–tritium fusion power production (up to 10.7 MW), Lawson triple product 1021 m−3 s keV), and energy confinement time 330 ms). The maximum current for access high-performance supershots been increased from 1.9 2.7 MA, leading stable operation at stored values greater than 5 MJ. amount on limiter...
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...
Oscillating MHD modes in JET are often observed to slow down as they grow and generally stop rotating (lock) when the amplitude exceeds a critical value, then continue large amplitudes (r/Bθ ∼ 1%). The mode can early current rise or after perturbations, such pellet injection sawtooth collapse, maintain throughout remainder of discharge. Such quasistationary apparently have profound effects on plasma, including stopping central ion plasma rotation, reducing changing shape sawteeth, flattening...
Anomalous momentum transport has been observed in Alcator C-Mod tokamak plasmas. The time evolution of core impurity toroidal rotation velocity profiles measured with a tangentially viewing crystal x-ray spectrometer array. Following the L-mode to EDA (enhanced Dα) H-mode transition both Ohmic and ion cyclotron range frequencies heated discharges, ensuing co-current velocity, which is generated absence any external source, propagate from edge plasma timescale order energy confinement time,...
A tokamak relies on the axisymmetric magnetic fields to confine fusion plasmas and aims deliver sustainable clean energy. However, misalignments arise inevitably in construction, leading small asymmetries field known as error (EFs). The EFs have been a major concern approaches because EFs, even less than 0.1%, can drive plasma disruption. Meanwhile, be favorably used for controlling instabilities, such edge-localized modes (ELMs). Here we show an optimization that tailors maintain edge 3D...
Abstract The path of tokamak fusion and International thermonuclear experimental reactor (ITER) is maintaining high-performance plasma to produce sufficient power. This effort hindered by the transient energy burst arising from instabilities at boundary plasmas. Conventional 3D magnetic perturbations used suppress these often degrade performance increase risk other instabilities. study presents an innovative field optimization approach that leverages machine learning real-time adaptability...
Co-current central impurity toroidal rotation has been observed in Alcator C-Mod plasmas with on-axis ICRF heating. The velocity increases plasma stored energy and decreases current. Very similar behaviour seen during ohmic H modes, which suggests that the rotation, generated absence of an external momentum source, is not mainly effect. A scan resonance location across performed order to investigate possible influences on rotation. With a slight reduction magnetic field from 4.7 4.5 T...
Factor of ∼2 higher power thresholds for low- to high-confinement mode transitions (L-H) with unfavorable x-point topologies in Alcator C-Mod [Phys. Plasmas 1, 1511 (1994)] are linked flow boundary conditions imposed by the scrape-off layer (SOL). Ballooning-like transport drives along magnetic field lines from high-field regions toroidal direction dependent on upper/lower balance; rotation confined plasma responds, exhibiting a strong counter-current when B×∇B points away x point. Increased...
Abstract The amplitude of locked instabilities, likely magnetic islands, seen as precursors to disruptions has been studied using data from the JET, ASDEX Upgrade and COMPASS tokamaks. It was found that thermal quench, often initiates disruption, is triggered when reached a distinct level. This information can be used determine thresholds for simple disruption prediction schemes. measured in part depends on distance perturbation measurement coils. Hence threshold mode location (i.e. rational...
Double transport barrier plasmas comprised of an edge enhanced Dα (EDA) H-mode pedestal and internal (ITB) have been observed in Alcator C-Mod. The ITB can be routinely produced ICRF heated by locating the wave resonance off-axis near |r/a|~0.5, provided target plasma average density is above ~1.4×1020 m-3, develop spontaneously some Ohmic discharges. formation appears conjunction with a decrease or reversal central (impurity) toroidal rotation velocity. foot located r/a~0.5, regardless how...
A comparison of experimental measurements and theoretical studies the quasicoherent (QC) mode, observed at high densities during enhanced D(alpha) (EDA) H mode in Alcator C-Mod tokamak, are reported. The QC is a frequency ( approximately 100 kHz) nearly sinusoidal fluctuation density magnetic field, localized steep gradient ("pedestal") plasma edge, with typical wave numbers k(R) 3-6 cm(-1), k(theta) 1.3 cm(-1) (midplane). It proposed here that form resistive ballooning known as X-point...
High resolution measurements on the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1551 (1994)] of transport barrier in “Enhanced Dα” (EDA) regime, which has increased particle without large edge localized modes, show steep density and temperature gradients over a region 2–5 mm, with peak pressure up to 12 MPa/m. Evolution pedestal at L-H transition is consistent large, rapid drop thermal conductivity across barrier. A quasi-coherent fluctuation density, potential, Bpol,...
Core plasma rotation is observed to change from counter direction co-current during the transition low (L) high (H) confinement mode, in Alcator C-Mod plasmas that are heated purely Ohmically and, hence, have no momentum input. The changes of toroidal velocities, deduced independently impurity Doppler measurements and magnetic perturbations associated with sawteeth, agree. magnitude consistent previously documented scaling for ion cyclotron rf-heated H modes. this Ohmic experiment obviously...