A. Bortolon
A5085937865- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Solar and Space Plasma Dynamics
- Semiconductor materials and devices
- Nuclear Materials and Properties
- Nuclear reactor physics and engineering
- Particle Detector Development and Performance
- Dust and Plasma Wave Phenomena
- Diamond and Carbon-based Materials Research
- Advancements in Semiconductor Devices and Circuit Design
- Nuclear Physics and Applications
- Photocathodes and Microchannel Plates
- Atomic and Subatomic Physics Research
- Metal and Thin Film Mechanics
- Atomic and Molecular Physics
- Structural Health Monitoring Techniques
- Silicon Carbide Semiconductor Technologies
- GNSS positioning and interference
- Laser-induced spectroscopy and plasma
- Electronic Packaging and Soldering Technologies
Princeton Plasma Physics Laboratory
2016-2025
Princeton University
2016-2024
University of California, Los Angeles
2012-2022
University of Wisconsin–Madison
2022
General Atomics (United States)
2018-2022
Oak Ridge National Laboratory
2021
Plasma Technology (United States)
2021
Fusion Academy
2021
Fusion (United States)
2021
University of California, Irvine
2010-2018
Abstract The most efficient and promising operational regime for the International Thermonuclear Experimental Reactor tokamak is high-confinement mode. In this regime, however, periodic relaxations of plasma edge can occur. These edge-localized modes pose a threat to integrity fusion device. Here we reveal strong impact energetic ions on spatio-temporal structure in tokamaks using nonlinear hybrid kinetic–magnetohydrodynamic simulations. A resonant interaction between fast at electromagnetic...
Parametric scalings of the intrinsic (spontaneous, with no external momentum input) toroidal rotation observed on a large number tokamaks have been combined an eye towards revealing underlying mechanism(s) and extrapolation to future devices. The velocity has found increase plasma stored energy or pressure in JET, Alcator C-Mod, Tore Supra, DIII-D, JT-60U TCV, decrease increasing current some these cases. Use dimensionless parameters led roughly unified scaling MA ∝ βN, although variety Mach...
The impact of plasma shaping on electron heat transport is investigated in TCV L-mode plasmas. study motivated by the observation an increase energy confinement time with decreasing triangularity which may not be explained a change temperature gradient induced changes geometry flux surfaces. varied over wide range, from positive to negative values, and various plasmas conditions are explored changing total cyclotron (EC) heating power density. mid-radius diffusivity shown significantly...
Toroidal momentum transport mechanisms are reviewed and put in a broader perspective. The generation of finite flux is closely related to the breaking symmetry (parity) along field. argument allows for systematic identification possible mechanisms. Those that appear lowest order normalized Larmor radius (the diagonal part, Coriolis pinch, E × B shearing, particle flux, up–down asymmetric equilibria) reasonably well understood. At higher order, expected be importance plasma edge, theory still...
Abstract In this paper, we present a brief historic overview of the research on dust in fusion devices with carbon plasma-facing components and then highlight most recent developments post-carbon era field. particular, consider how metallic form, mobilize, interact plasmas plasma facing components. Achievements wall conditioning associated anomalous transport modification, including ELM suppression, powder injection technique is another focus paper. Capabilities state-of-art simulation tools...
Bulk plasma toroidal rotation is observed to invert spontaneously from counter cocurrent direction in TCV (Tokamak \`a Configuration Variable) Ohmically heated discharges, low confinement mode, without momentum input. The inversion occurs high current when the electron density exceeds a well-defined threshold. transition between two rotational regimes has been studied by means of ramps. results provide evidence change balance nondiffusive fluxes core an external drive.
Direction reversals of intrinsic toroidal rotation have been observed in Alcator C-Mod ohmic L-mode plasmas following modest electron density or magnetic field ramps. The reversal process occurs the plasma interior, inside q = 3/2 surface. For low plasmas, is co-current direction, and can reverse to counter-current direction an increase above a certain threshold. Reversals from co- are correlated with sharp decrease fluctuations k R ⩾ 2 cm −1 frequencies 70 kHz. at which reverses increases...
The numerical methods used in the full particle-orbit following SPIRAL code are described and a number of physics studies performed with presented to illustrate its capabilities. is test-particle powerful tool interpret plan fast-ion experiments tokamaks. Gyro-orbit effects important for fast ions low-field machines such as NSTX lesser extent DIII-D. A interlaced between description Results on heat loads generated by localized error-field DIII-D wall compared measurements. enhanced Triton...
In ASDEX Upgrade with full-tungsten wall, boronization is an important tool to control tungsten sources and allow reliable operation at low collisionality. The duration of the beneficial effects limited by erosion boron layer, in particular on ion-cyclotron antenna limiters. We report results from experiments exploring injection boron-rich powders tokamak plasmas as a way replenish coating extend lifetime effects. Pure nitride were introduced gravitationally plasma discharges rates up 60...
Abstract In state-of-the-art stellarators, turbulence is a major cause of the degradation plasma confinement. To maximize confinement, which eventually determines amount nuclear fusion reactions, turbulent transport needs to be reduced. Here we report observation confinement regime in stellarator that characterized by increased and reduced fluctuations. The transition this driven injection submillimetric boron powder grains into plasma. With line-averaged electron density being kept...
Multimachine empirical scaling predicts an extremely narrow heat exhaust layer in future high magnetic field tokamaks, producing power densities that require mitigation. In the experiments presented, width of this is nearly doubled using actuators to increase turbulent transport plasma edge. This achieved low collisionality, confinement edge pedestals with their gradients limited by instead large-scale, coherent instabilities. The flux profile and divertor leg diffusive spreading both double...
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...
Predicting intrinsic plasma rotation and its shear, which often help stabilize instabilities affecting performance, is important for prospective fusion grade devices. Although in ITER-like scenarios has been extrapolated from measured experimental data, little understood about the underlying mechanisms governing either generation or dissipation of momentum a tokamak plasma. This paper reports on studies toroidal poloidal charge exchange spectroscopy using low power diagnostic beam TCV...
Research on the National Spherical Torus Experiment, NSTX, targets physics understanding needed for extrapolation to a steady-state ST Fusion Nuclear Science Facility, pilot plant, or DEMO. The unique operational space is leveraged test theories next-step tokamak operation, including ITER. Present research also examines implications coming device upgrade, NSTX-U. An energy confinement time, τE, scaling unified varied wall conditions exhibits strong improvement of BTτE with decreased electron...
We present a device for controlled injection of variety materials in powder form. The system implements four independent feeder units, arranged to share single vertical drop tube. Each unit consists 80 ml reservoir, coupled horizontal linear trough, where layer is advanced by piezo-electric agitation at speed proportional the applied voltage, until it falls into dropper has been tested with number impurities low (B, BN, C), intermediate (Si, SiC), and high Z (Sn) microscopic structures...
Abstract A newly installed Lithium Granule Injector (LGI) was used to pace edge localized modes (ELM) in DIII-D. ELM pacing efficiency studied injecting lithium granules of nominal diameter 0.3–0.9 mm, speed 50–120 m s −1 and average injection rates up 100 Hz for 0.9 mm 700 0.3 granules. The triggering found depend strongly on size the injected granules, with close 100% obtained lower smaller sizes, weakly depending granule velocity. Robust demonstrated ITER-like plasmas entire shot length,...
Abstract We report an observation of robust suppression edge-localized modes (ELMs) in the Experimental Advanced Superconducting Tokamak (EAST), enabled by continuous boron (B) powder injection. Edge harmonic oscillations appear during B injection, providing sufficient particle transport to maintain constant density and avoid impurity accumulation ELM-stable plasmas. Quasi-steady ELM discharges are demonstrated with modest energy confinement improvement over a wide range conditions: heating...
Abstract Using a recently installed impurity powder dropper (IPD), boron (<150 μ m) was injected into lower single null (LSN) L-mode discharges in WEST. IPDs possibly enable real-time wall conditioning of the plasma-facing components and may help to facilitate H-mode access full-tungsten environment The this experiment featured I p = 0.5 MA, B T 3.7 T, q 95 4.3, t pulse 12–30 s, n e,0 ∼ 4 × 10 19 m −2 , P LHCD 4.5 MW. Estimates deuterium particle fluxes, derived from combination visible...
Abstract The plasma and neutral density dynamics after an edge localized mode are investigated utilized to infer the transport coefficients for pedestal. Lyman-Alpha Measurement Apparatus (LLAMA) diagnostic provides sub-millisecond profile measurements of ionization shows significant poloidal asymmetries in both. Exploiting absolute calibration LLAMA allows quantitative comparison electron main ion profiles determined by charge-exchange recombination, Thomson scattering interferometry....
Abstract Experimental measurements on DIII-D of hydrogen neutral penetration lengths ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>λ</mml:mi> <mml:mrow> <mml:mi>n</mml:mi> <mml:mn>0</mml:mn> </mml:msub> </mml:mrow> </mml:math> ) the high field side (HFS) are longer by a factor <mml:msqrt> <mml:mn>2</mml:mn> </mml:msqrt> than for deuterium consistent with thermal velocity ratio neutrals at same temperature <mml:mo stretchy="false">(</mml:mo>...
Abstract Experiments on ASDEX Upgrade (AUG) in 2021 and 2022 have addressed a number of critical issues for ITER EU DEMO. A major objective the AUG programme is to shed light underlying physics confinement, stability, plasma exhaust order allow reliable extrapolation results obtained present day machines these reactor-grade devices. Concerning pedestal physics, mitigation edge localised modes (ELMs) using resonant magnetic perturbations (RMPs) was found be consistent with reduction linear...
The Alfvén instability nonlinearly excited the energetic-particle-driven geodesic acoustic mode on ASDEX-Upgrade tokamak, as demonstrated experimentally. mechanism of excitation and nonlinear evolution is not yet fully understood. In present work, a first-principles simulation using MEGA code investigated properties in both linear growth saturated phases. Here we show that successfully reproduced coexistence these two modes, agreed with experimental results well. Conclusive evidence showed...
Abstract On the basis of several recent breakthroughs in fusion research, many activities have been launched around world to develop power plants on fastest possible time scale. In this context, high-fidelity simulations plasma behavior large supercomputers provide one main pathways accelerating progress by guiding crucial design decisions. When it comes determining energy confinement a magnetic device, which is key quantity interest, gyrokinetic turbulence are considered approach choice –...