A5027187696- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Fusion materials and technologies
- Solar and Space Plasma Dynamics
- Superconducting Materials and Applications
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Nuclear reactor physics and engineering
- Atomic and Subatomic Physics Research
- GNSS positioning and interference
- Particle Detector Development and Performance
- Nuclear Physics and Applications
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Geophysics and Gravity Measurements
- Radiation Effects in Electronics
- Nuclear Materials and Properties
- Atomic and Molecular Physics
- Dust and Plasma Wave Phenomena
- Advanced Data Storage Technologies
- Particle physics theoretical and experimental studies
- Electromagnetic Launch and Propulsion Technology
- earthquake and tectonic studies
- Nuclear physics research studies
Princeton Plasma Physics Laboratory
2015-2024
Princeton University
2014-2024
École Polytechnique Fédérale de Lausanne
2004-2024
Culham Science Centre
2024
Culham Centre for Fusion Energy
2024
Lodestar Research Corporation (United States)
2020
Lawrence Livermore National Laboratory
2020
National Technological University
2018
University of Wisconsin–Madison
2013
Nova Photonics (United States)
2010-2012
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 mechanism for blob generation in a toroidal magnetized plasma is investigated using time-resolved measurements of two-dimensional structures electron density, temperature, and potential. blobs are observed to form from radially elongated structure that sheared off by the $\mathbf{E}\ifmmode\times\else\texttimes\fi{}\mathbf{B}$ flow. generated an interchange wave increases amplitude extends response decrease radial pressure scale length. dependence upon length discussed.
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>...
Gradient driven electrostatic instabilities are investigated in TORPEX [A. Fasoli, B. Labit, M. McGrath, S. H. Müller, Podestà, and F. Poli, Bull. Am. Phys. Soc. 48, 119 (2003)], a toroidal device (R=1m, a=0.2m) which plasmas produced by microwaves (P⩽20kW) with frf=2.45GHz, the electron cyclotron frequency range. Typical density temperature ne⩽1017m−3 Te≃5eV, respectively. The magnetic field is mainly (⩽0.1T), small vertical component (⩽4mT). Instabilities that can be generally identified...
The resistive wall mode (RWM) instability in high-beta tokamaks is stabilized by energy dissipation mechanisms that depend on plasma rotation and kinetic effects. Kinetic modification of ideal stability calculated with the “MISK” code [B. Hu et al., Phys. Plasmas 12, 057301 (2005)] outlined. For an advanced scenario ITER [R. Aymar Nucl. Fusion 41, 1301 (2001)] plasma, present calculation finds alpha particles are required for RWM at presently expected levels rotation. stabilization theory...
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...
Remarkable progress has been made in diagnosing energetic particle instabilities on presentday machines and establishing a theoretical framework for describing them.This overview describes the much improved diagnostics of Alfvén modelling tools developed world-wide, discusses interpreting observed phenomena.A multi-machine comparison is presented giving information performance both different plasma conditions outlining expectations ITER based our present knowledge.
Fast ion transport models currently implemented in the tokamak code TRANSP (Hawryluk 1980 Physics of Plasmas Close to Thermonuclear Conditions (Brussels: CEC)) are not capturing important aspects physics associated with resonant caused by instabilities such as toroidal Alfven eigenmodes (TAEs). This work describes implementation a fast model consistent basic mechanisms mode–particle interaction. The is formulated terms probability distribution function for particle's steps phase space, which...
Abstract The SMall Aspect Ratio Tokamak (SMART) under commissioning at the University of Seville, Spain, aims to explore confinement properties and possible advantages in for compact/spherical tokamaks operating negative vs. positive triangularity. This work explores benefits auxiliary heating through Neutral Beam Injection (NBI) SMART scenarios beyond initial Ohmic phase operations, support device’s mission. Expected values electron ion temperature achievable with NBI are first predicted...
Abstract ST40 is a compact, high-field ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>B</mml:mi> <mml:mi mathvariant="normal">T</mml:mi> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mtext>⩽</mml:mtext> <mml:mn>2.1</mml:mn> <mml:mstyle scriptlevel="0"/> <mml:mtext>T</mml:mtext> </mml:math> ) spherical tokamak (ST) with mission to expand the physics and technology basis for ST route commercial fusion. The research programme covers...
A unique parabolic relation is observed to link skewness and kurtosis of around ten thousand density fluctuation signals, measured over the whole cross section a toroidal magnetized plasma for broad range experimental conditions. All probability functions including those characterized by negative skewness, are universally described special case Beta distribution. Fluctuations in drift-interchange frequency necessary sufficient assure that can be this specific
Experimental results from NSTX indicate that the snowflake divertor (D. Ryutov, Phys. Plasmas 14, 064502 (2007)) may be a viable solution for outstanding tokamak plasma-material interface issues. Steady-state handling of heat flux and plate erosion remains to critical issues ITER future concept devices based on conventional spherical geometry with high power density divertors. Experiments conducted in 4–6 MW NBI-heated H-mode plasmas demonstrated is compatible high-confinement core plasma...
Understanding the dependence of confinement on collisionality in tokamaks is important for design next-step devices, which will operate at collisionalities least one order magnitude lower than present generation. A wide range has been obtained National Spherical Torus Experiment (NSTX) by employing two different wall conditioning techniques, with boronization and between-shot helium glow discharge (HeGDC+B), using lithium evaporation (Li EVAP). Previous studies HeGDC+B plasmas indicated a...
The National Spherical Torus Experiment (NSTX) has undergone a major upgrade, and the NSTX Upgrade (NSTX-U) Project was completed in summer of 2015.NSTX-U first plasma subsequently achieved, diagnostic control systems have been commissioned, H-mode accessed, magnetic error fields identified mitigated, physics research campaign carried out.During ten run weeks operation, NSTX-U surpassed record pulse-durations toroidal (TF), high-performance ~1 MA plasmas comparable to best sustained near...
The fusion-born alpha particle heating in magnetically confined fusion machines is a high priority subject for studies. self-heating of thermonuclear plasma by particles was observed recent deuterium-tritium (D-T) experiments on the joint European torus. This observation possible conducting so-called "afterglow" where transient yield achieved with neutral beam injection as only external source, and then termination at peak performance. allowed first direct evidence electron plasmas alphas to...
Abstract Burning reactor plasmas will be self-heated by fusion born alpha particles from deuterium-tritium reactions. Consequently, a thorough understanding of the confinement and transport DT-born is necessary to maintain plasma self-heating. Measurements fast ion losses provide direct means monitor particle confinement. JET’s 2021–2022 second experimental DT-campaign offers burning scenarios with advanced loss diagnostics for first time in nearly 25 years. Coherent non-coherent were...
The mechanism for blob generation is detailed in the toroidal magnetized plasma of TORPEX device [Fasoli et al., Phys. Plasmas 13, 055902 (2006)] using an experimental configuration, which features a region dominated by coherent wave and on low field side characterized propagation blobs. Predictions from linearized 2D drift-reduced Braginskii equations are compared with data, revealing interchange nature wave. dynamics formation investigated time-resolved measurements two-dimensional...
A new diagnostic, aimed at energy-resolved measurements of the spatial and temporal dynamics fast ions in NSTX plasmas, is described. It based on active charge-exchange recombination spectroscopy. The fast-ion signal inferred from light emitted wavelength range Dα line by recombining with an injected neutral beam. Two complementary systems are operational. first system, a spectrometer coupled to charge device detector, has 16 channels space, time, energy resolution 5cm, 10ms, 10keV,...
Experiments on the National Spherical Torus Experiment [M. Ono et al., Nucl. Fusion 40, 557 (2000)] found strong bursts of toroidal Alfvén eigenmode (TAE) activity correlated with abrupt drops in neutron rate. A fairly complete data set offers opportunity to benchmark NOVA [C. Z. Cheng, Phys. Rep. 211, 1 (1992)] and ORBIT [R. B. White M. S. Chance, Fluids 27, 2455 (1984)] codes low aspect ratio tokamak (ST) geometry. The internal structure TAE was modeled good agreement is measurements made...
Fast-ion transport induced by Alfvén eigenmodes (AEs) is studied in beam-heated plasmas on the National Spherical Torus Experiment [Ono et al., Nucl. Fusion 40, 557 (2000)] through space, time, and energy resolved measurements of fast-ion population. losses associated with multiple toroidicity-induced AEs (TAEs), which interact nonlinearly terminate avalanches, are characterized. A depletion range &gt;20 keV, leading to sudden drops up 40% neutron rate over 1 ms, observed a broad spatial...
Global modes?including kinks and tearing modes (f ~ 400?kHz)?play critical roles in many aspects of plasma performance. Their investigation on NSTX is aided by an array fixed-frequency quadrature reflectometers used to determine their radial density perturbation structure. The has been recently upgraded 16 channels spanning 30?75?GHz (ncutoff = (1.1?6.9) ? 1019?m?3 O-mode), improving spatial sampling access the core H-mode plasmas. upgrade yielded significant new results that advance...
The application of static magnetic field perturbations to a tokamak plasma is observed alter the dynamics high-frequency bursting Alfv\'en modes that are driven unstable by energetic ions. In response with an amplitude $\ensuremath{\delta}B/B\ensuremath{\sim}0.01$ at boundary, mode reduced, frequency increased, and chirp smaller. For weaker character, perturbation induces temporary transition saturated continuous mode. Calculations perturbed distribution function indicate 3D affects orbits...
Analysis of neutron and fast-ion Dα data from the DIII-D tokamak shows that Alfvén eigenmode activity degrades confinement in many high βN, qmin, steady-state scenario discharges. (βN is normalized plasma pressure qmin minimum value safety factor.) Fast-ion diagnostics are sensitive to co-passing population exhibit largest reduction relative classical predictions. The increased transport discharges with strong AE accounts for previously observed global increasing qmin; however, not all show...
A general criterion is proposed and found to successfully predict the emergence of chirping oscillations unstable Alfvénic eigenmodes in tokamak plasma experiments. The model includes realistic eigenfunction structure, detailed phase-space dependences instability drive, stochastic scattering Coulomb drag. combines effects collisional pitch angle micro-turbulence spatial diffusion. latter mechanism essential accurately identify transition between fixed-frequency mode behavior rapid tokamaks...
Alfvénic instabilities (AEs) are well known as a potential cause of enhanced fast ion transport in fusion devices. Given specific plasma scenario, quantitative predictions (i) expected unstable AE spectrum and (ii) resulting required to prevent or mitigate the AE-induced degradation performance. Reduced models becoming an attractive tool analyze existing scenarios for scenario prediction time-dependent simulations. In this work, neutral beam heated NSTX discharge is used reference illustrate...