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| Open AccessAvoiding fusion plasma tearing instability with deep reinforcement learning
Artificial intelligence control is used to avoid the emergence of disruptive tearing instabilities in the magnetically confined fusion plasma in the DIII-D tokamak reactor.
- Jaemin Seo
- , SangKyeun Kim
- & Egemen Kolemen
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Article |
Observing the onset of pressure-driven K-shell delocalization
Experiments at the National Ignition Facility show how delocalization of K-shell electrons is driven by extreme pressure and temperature.
- T. Döppner
- , M. Bethkenhagen
- & D. O. Gericke
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Article |
Coherent surface plasmon polariton amplification via free-electron pumping
Stimulated emission by free electrons is used to amplify terahertz surface plasmon polaritons in a manner resembles that of light amplification in a high-gain free-electron laser.
- Dongdong Zhang
- , Yushan Zeng
- & Ruxin Li
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Article |
A sustained high-temperature fusion plasma regime facilitated by fast ions
A magnetic confinement regime established at the Korea Superconducting Tokamak Advanced Research device enables the generation of plasmas over 108 kelvin for 20 seconds with the aid of fast ions without plasma edge instabilities or impurity accumulation.
- H. Han
- , S. J. Park
- & Y.-S. Na
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Article |
Free-electron lasing with compact beam-driven plasma wakefield accelerator
Using a compact, particle-beam-driven plasma-based accelerator to accelerate high-quality electron beams that are completely characterized in the six-dimensional phase space, free-electron lasing is observed with narrow-band amplified radiation in the infrared range.
- R. Pompili
- , D. Alesini
- & M. Ferrario
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Article
| Open AccessRecovery time of a plasma-wakefield accelerator
Relaxation of a perturbed plasma back to its initial state over nanosecond timescales establishes that megahertz repetition rates are supported, and high luminosities and brilliances are in principle attainable with plasma-wakefield accelerator facilities.
- R. D’Arcy
- , J. Chappell
- & J. Osterhoff
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Article
| Open AccessMagnetic control of tokamak plasmas through deep reinforcement learning
A newly designed control architecture uses deep reinforcement learning to learn to command the coils of a tokamak, and successfully stabilizes a wide variety of fusion plasma configurations.
- Jonas Degrave
- , Federico Felici
- & Martin Riedmiller
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Article
| Open AccessBurning plasma achieved in inertial fusion
A burning plasma, a critical step towards self-sustaining fusion, is achieved at the US National Ignition Facility, with a subset of experiments demonstrating fusion self-heating beyond radiation and conduction losses.
- A. B. Zylstra
- , O. A. Hurricane
- & G. B. Zimmerman
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Article
| Open AccessIn-orbit demonstration of an iodine electric propulsion system
The successful in-orbit operation of an electric space propulsion system based on iodine, rather than the more expensive and difficult-to-store xenon, is demonstrated.
- Dmytro Rafalskyi
- , Javier Martínez Martínez
- & Ane Aanesland
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Article
| Open AccessDemonstration of reduced neoclassical energy transport in Wendelstein 7-X
Previously documented record values of the fusion triple product in the stellarator Wendelstein 7-X are shown to be evidence for reduced neoclassical energy transport in this optimized device.
- C. D. Beidler
- , H. M. Smith
- & M. Zuin
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Article |
Free-electron lasing at 27 nanometres based on a laser wakefield accelerator
Lasing in the extreme-ultraviolet range is demonstrated using a laser wakefield accelerator, as a step towards compact X-ray free-electron lasers.
- Wentao Wang
- , Ke Feng
- & Zhizhan Xu
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Perspective |
The data-driven future of high-energy-density physics
This Perspective discusses how high-energy-density physics could tap the potential of AI-inspired algorithms for extracting relevant information and how data-driven automatic control routines may be used for optimizing high-repetition-rate experiments.
- Peter W. Hatfield
- , Jim A. Gaffney
- & Ben Williams
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Article |
Stabilization of liquid instabilities with ionized gas jets
A weakly ionized gas jet impinging on a water surface is shown to produce a more stable cavity than does a neutral gas jet, with implications for plasma–liquid interactions.
- Sanghoo Park
- , Wonho Choe
- & Uroš Cvelbar
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Article |
Observation of the onset of a blue jet into the stratosphere
Observations from the International Space Station show a blue jet that is initiated by an intense blue flash in the top of a thunderstorm cloud.
- Torsten Neubert
- , Olivier Chanrion
- & Victor Reglero
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Article |
A measurement of the equation of state of carbon envelopes of white dwarfs
Researchers have measured the equation of state of hydrocarbon in a high-density regime, which is necessary for accurate modelling of the oscillations of white dwarf stars.
- Andrea L. Kritcher
- , Damian C. Swift
- & Siegfried H. Glenzer
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Article |
Alfvénic velocity spikes and rotational flows in the near-Sun solar wind
Data collected by the Parker Solar Probe in the solar corona are used to determine the organization of Alfvén waves, revealing an increasing flow velocity peaking at 35–50 km s−1.
- J. C. Kasper
- , S. D. Bale
- & N. A. Schwadron
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Letter |
Needle-like structures discovered on positively charged lightning branches
Radio interferometric observations of lightning over the Netherlands reveal small needle-shaped plasma structures associated with the positive leader channels, explaining why cloud-to-ground lightning connects to the ground multiple times.
- B. M. Hare
- , O. Scholten
- & P. Zucca
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Letter |
Predicting disruptive instabilities in controlled fusion plasmas through deep learning
Using data from plasma-based tokamak nuclear reactors in the US and Europe, a machine-learning approach based on deep neural networks is taught to forecast disruptions, even those in machines on which the algorithm was not trained.
- Julian Kates-Harbeck
- , Alexey Svyatkovskiy
- & William Tang
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Letter |
Flight of an aeroplane with solid-state propulsion
A solid-state propulsion system can sustain powered flight, as demonstrated by an electroaerodynamically propelled heavier-than-air aeroplane.
- Haofeng Xu
- , Yiou He
- & Steven R. H. Barrett
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Letter
| Open AccessAcceleration of electrons in the plasma wakefield of a proton bunch
Electron acceleration to very high energies is achieved in a single step by injecting electrons into a ‘wake’ of charge created in a 10-metre-long plasma by speeding long proton bunches.
- E. Adli
- , A. Ahuja
- & G. Xia
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Letter |
Resolved atomic lines reveal outflows in two ultraluminous X-ray sources
Ultraluminous X-ray sources are thought to be powered by accretion onto a compact object; now the discovery of X-ray emission lines and blueshifted absorption lines in the high-resolution spectra of ultraluminous X-ray sources NGC 1313 X-1 and NGC 5408 X-1 shows that in each case the compact object is surrounded by powerful winds with an outflow velocity of about 0.2 times that of light.
- Ciro Pinto
- , Matthew J. Middleton
- & Andrew C. Fabian
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Letter |
Multistage coupling of independent laser-plasma accelerators
Laser-plasma particle accelerators offer much higher acceleration than conventional methods, which could enable high-energy applications; here two separate accelerator stages, driven by two independent lasers, are coupled using plasma-based optics.
- S. Steinke
- , J. van Tilborg
- & W. P. Leemans
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Letter |
A dynamic magnetic tension force as the cause of failed solar eruptions
Coronal mass ejections are driven by a sudden release of magnetic energy stored in flux ropes in the Sun’s corona, but when the ambient magnetic field that runs toroidally along an unstable flux rope is strong enough to prevent the flux rope from kinking, a dynamic magnetic tension force halts the eruption.
- Clayton E. Myers
- , Masaaki Yamada
- & Edward E. DeLuca
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Letter |
Atomic inner-shell laser at 1.5-ångström wavelength pumped by an X-ray free-electron laser
A copper target is used to achieve an atomic laser in the hard-X-ray regime with strong amplified spontaneous coherent emission at a wavelength ten times shorter than previous lasers have achieved.
- Hitoki Yoneda
- , Yuichi Inubushi
- & Makina Yabashi
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Letter |
Multi-gigaelectronvolt acceleration of positrons in a self-loaded plasma wakefield
A particle accelerator that is two orders of magnitude more efficient than conventional radio-frequency accelerators is described in which positrons (rather than electrons) at the front of a bunch transfer their energy to a substantial number of positrons at the rear of the same bunch by exciting a wakefield in the plasma.
- S. Corde
- , E. Adli
- & G. Yocky
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Letter |
A higher-than-predicted measurement of iron opacity at solar interior temperatures
Laboratory measurements of iron opacity made under conditions similar to those inside the Sun reveal much higher opacity than predicted, helping to resolve inconsistencies within stellar models of the internal temperatures of stars.
- J. E. Bailey
- , T. Nagayama
- & B. G. Wilson
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Letter |
High-efficiency acceleration of an electron beam in a plasma wakefield accelerator
To develop plasma wakefield acceleration into a compact and affordable replacement for conventional accelerators, beams of charged particles must be accelerated at high efficiency in a high electric field; here this is demonstrated for a bunch of charged electrons ‘surfing’ on a previously excited plasma wave.
- M. Litos
- , E. Adli
- & G. Yocky
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Letter |
Fuel gain exceeding unity in an inertially confined fusion implosion
Fusion fuel gains greater than unity — which are crucial to the generation of fusion energy — are achieved on the US National Ignition Facility using the ‘high-foot’ implosion method, which reduces instability in the implosion of the fuel.
- O. A. Hurricane
- , D. A. Callahan
- & R. Tommasini
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Letter |
Flux-freezing breakdown in high-conductivity magnetohydrodynamic turbulence
A magnetohydrodynamic simulation of a magnetized plasma at high conductivity shows that, whereas the magnetic flux can be considered ‘frozen’ into the medium for laminar flow, in a turbulent medium the motion of the field lines can become indeterministic, leading to a breakdown in flux freezing.
- Gregory Eyink
- , Ethan Vishniac
- & Alexander Szalay
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Letter |
No meridional plasma flow in the heliosheath transition region
The radially outward flow of plasma from the Sun is expected to be deflected when it meets the flow of interstellar plasma through which the Solar System moves, but the spacecraft Voyager 1 unexpectedly finds that the deflected, meridional, flow is consistent with zero within the transition region.
- Robert B. Decker
- , Stamatios M. Krimigis
- & Matthew E. Hill
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Letter |
Magnetic reconnection from a multiscale instability cascade
Laboratory observations show how a macroscopic magnetohydrodynamic plasma instability drives a fine-scale secondary instability that is associated with magnetic reconnection.
- Auna L. Moser
- & Paul M. Bellan
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Research Highlights |
Mercury's plasma belt
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Letter |
Zero outward flow velocity for plasma in a heliosheath transition layer
- Stamatios M. Krimigis
- , Edmond C. Roelof
- & Matthew E. Hill
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News |
Antimatter held for questioning
Magnetically trapped atoms could test fundamental physics.
- Eugenie Samuel Reich
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News |
Delays prompt reshuffle at ITER fusion project
Interim director appointed to Europe's part of programme.
- Geoff Brumfiel
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Research Highlights |
Physics: Plasma pinch
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Letter |
A large coronal loop in the Algol system
The close binary Algol system contains a radio-bright KIV sub-giant star in a very close and rapid orbit with a main sequence B8 star. Evidence points to the existence of an extended, complex coronal magnetosphere originating at the cooler K subgiant, but the detailed morphology of the subgiant's corona and its possible interaction with its companion are unknown. Multi-epoch radio imaging of the Algol system now reveals a large coronal loop suggestive of a persistent asymmetric magnetic field structure aligned between the two stars.
- W. M. Peterson
- , R. L. Mutel
- & W. M. Goss