The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
A. J. Bennett - One of the best experts on this subject based on the ideXlab platform.
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relativistic Electron Beams above thunderclouds
Atmospheric Chemistry and Physics, 2011Co-Authors: Martin Füllekrug, E. M. D. Symbalisty, J. J. Colman, O. Van Der Velde, A. Odzimek, R A Rousseldupre, Olivier Chanrion, Serge Soula, A. J. BennettAbstract:Non-luminous relativistic Electron Beams above thunderclouds have been detected by the radio signals of low frequency 40-400 kHz which they radiate. The Electron Beams occur 2-9 ms after positive cloud-to-ground light- ning discharges at heights between 22-72 km above thun- derclouds. Intense positive lightning discharges can also cause sprites which occur either above or prior to the elec- tron beam. One Electron beam was detected without any lu- minous sprite which suggests that Electron Beams may also occur independently of sprites. Numerical simulations show that Beams of Electrons partially discharge the lightning elec- tric field above thunderclouds and thereby gain a mean en- ergy of 7 MeV to transport a total charge of 10 mC up- wards. The impulsive current 3◊ 10 3 Am 2 associated with relativistic Electron Beams above thunderclouds is di- rected downwards and needs to be considered as a novel ele- ment of the global atmospheric electric circuit.
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Relativistic Electron Beams above thunderclouds
Atmospheric Chemistry and Physics Discussions, 2011Co-Authors: Martin Füllekrug, Robert Roussel-dupré, E. M. D. Symbalisty, J. J. Colman, O. Van Der Velde, A. Odzimek, Olivier Chanrion, Serge Soula, A. J. Bennett, Victor P. PaskoAbstract:Abstract. Non-luminous relativistic Electron Beams above thunderclouds are detected by radio remote sensing with low frequency radio signals from 40–400 kHz. The Electron Beams occur 2–9 ms after positive cloud-to-ground lightning discharges at heights between 22–72 km above thunderclouds. The positive lightning discharges also cause sprites which occur either above or before the Electron beam. One Electron beam was detected without any luminous sprite occurrence which suggests that Electron Beams may also occur independently. Numerical simulations show that the beamed Electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of 7 MeV to transport a total charge of 10 mC upwards. The impulsive current associated with relativistic Electron Beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit.
HJ McAndrews - One of the best experts on this subject based on the ideXlab platform.
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Formation of Saturn's ring spokes by lightning-induced Electron Beams
Geophysical Research Letters, 2006Co-Authors: HJ McAndrewsAbstract:Spokes are near-linear markings sometimes visible on Saturn's rings. They are widely accepted as being electrostatically-levitated sheets of similar to 0.6 micron-radius charged grains. Previously-suggested causes of the grains' charging do not agree with all spoke characteristics, which include their rapid generation, localized formation primarily in Saturn's midnight-dawn sector, the seasonality of their apparitions, and, crucially, their morphologies. We contend that spokes are caused by lightning-induced Electron Beams striking the rings, at locations magnetically-connected to thunderstorms. This view is supported by a semi-quantitative spoke morphology simulation. Spokes' formation locations are further controlled by Saturn's ionospheric density, which reaches a near-dawn minimum where Electron Beams can most easily propagate to the rings. The Beams may generate observed X-ray emission, supply particles to Saturn's radiation belts, and over time will modify the rings' constituents. Finally, we report Cassini MIMI instrument observations of an Electron burst which displays some characteristics expected of a lightning-induced event.
Jie Zhang - One of the best experts on this subject based on the ideXlab platform.
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ultrahigh charge Electron Beams from laser irradiated solid surface
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: J Zhao, Zhengming Sheng, Liming Chen, Jianxun Liu, S J D Dann, Xiaohu Yang, Jie ZhangAbstract:Compact acceleration of a tightly collimated relativistic Electron beam with high charge from a laser–plasma interaction has many unique applications. However, currently the well-known schemes, including laser wakefield acceleration from gases and vacuum laser acceleration from solids, often produce Electron Beams either with low charge or with large divergence angles. In this work, we report the generation of highly collimated Electron Beams with a divergence angle of a few degrees, nonthermal spectra peaked at the megaElectronvolt level, and extremely high charge (∼100 nC) via a powerful subpicosecond laser pulse interacting with a solid target in grazing incidence. Particle-in-cell simulations illustrate a direct laser acceleration scenario, in which the self-filamentation is triggered in a large-scale near–critical-density plasma and Electron bunches are accelerated periodically and collimated by the ultraintense electromagnetic field. The energy density of such Electron Beams in high-Z materials reaches to ∼ 1 0 12 J / m 3 , making it a promising tool to drive warm or even hot dense matter states.
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concurrence of monoenergetic Electron Beams and bright x rays from an evolving laser plasma bubble
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Wenchao Yan, Nasr A M Hafz, Zhengming Sheng, Liming Chen, L Zhang, J Dunn, Kai Huang, Min Chen, Jie ZhangAbstract:Desktop laser plasma acceleration has proven to be able to generate gigaElectronvolt-level quasi-monoenergetic Electron Beams. Moreover, such Electron Beams can oscillate transversely (wiggling motion) in the laser-produced plasma bubble/channel and emit collimated ultrashort X-ray flashes known as betatron radiation with photon energy ranging from kiloElectronvolts to megaElectronvolts. This implies that usually one cannot obtain bright betatron X-rays and high-quality Electron Beams with low emittance and small energy spread simultaneously in the same accelerating wave bucket. Here, we report the first (to our knowledge) experimental observation of two distinct Electron bunches in a single laser shot, one featured with quasi-monoenergetic spectrum and another with continuous spectrum along with large emittance. The latter is able to generate high-flux betatron X-rays. Such is observed only when the laser self-guiding is extended over 4 mm at a fixed plasma density (4 × 1018 cm−3). Numerical simulation reveals that two bunches of Electrons are injected at different stages due to the bubble evolution. The first bunch is injected at the beginning to form a stable quasi-monoenergetic Electron beam, whereas the second one is injected later due to the oscillation of the bubble size as a result of the change of the laser spot size during the propagation. Due to the inherent temporal synchronization, this unique Electron–photon source can be ideal for pump–probe applications with femtosecond time resolution.
P Musumeci - One of the best experts on this subject based on the ideXlab platform.
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superradiant and stimulated superradiant emission of bunched Electron Beams
Reviews of Modern Physics, 2019Co-Authors: A Gover, Reuven Ianconescu, A Friedman, C Emma, N Sudar, P Musumeci, C PellegriniAbstract:Electron Beams can generate radiation spanning a wide range of the electromagnetic spectrum. Creating temporal structure in the beam density results in intense radiation emission proportional to the square of the particle number as compared to the linear dependence on particle number from a randomly distributed Electron beam. In this article various coherent radiation emission processes are discussed including spontaneous emission, coherent spontaneous superradiance, and stimulated superradiance.
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knife edge based measurement of the 4d transverse phase space of Electron Beams with picometer scale emittance
Physical review accelerators and beams, 2019Co-Authors: Jorge Giner Navarro, P Musumeci, Daniel B Durham, Andrew M Minor, D FilippettoAbstract:Author(s): Ji, F; Navarro, JG; Musumeci, P; Durham, DB; Minor, AM; Filippetto, D | Abstract: © 2019 authors. Published by the American Physical Society. Precise manipulation of high brightness Electron Beams requires detailed knowledge of the particle phase space shape and evolution. As ultrafast Electron pulses become brighter, new operational regimes become accessible with emittance values in the picometer range, with enormous impact on potential scientific applications. Here we present a new characterization method for such Beams and demonstrate experimentally its ability to reconstruct the 4D transverse beam matrix of strongly correlated Electron Beams with subnanometer emittance and submicrometer spot size, produced with the HiRES beamline at Lawrence Berkeley National Laboratory. Our work extends the reach of ultrafast Electron accelerator diagnostics into picometer-range emittance values, opening the way to complex nanometer-scale Electron beam manipulation techniques.
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knife edge based measurement of the 4d transverse phase space of Electron Beams with picometer scale emittance
arXiv: Accelerator Physics, 2019Co-Authors: Jorge Giner Navarro, P Musumeci, Daniel B Durham, Andrew M Minor, D FilippettoAbstract:Precise manipulation of high brightness Electron Beams requires detailed knowledge of the particle phase space shape and evolution. As ultrafast Electron pulses become brighter, new operational regimes become accessible with emittance values in the picometer range, with enormous impact on potential scientific applications. Here we present a new characterization method for such Beams and demonstrate experimentally its ability to reconstruct the 4D transverse beam matrix of strongly correlated Electron Beams with sub-nanometer emittance and sub-micrometer spot size, produced with the HiRES beamline at LBNL. Our work extends the reach of ultrafast Electron accelerator diagnostics into picometer-range emittance values, opening the way to complex nanometer-scale Electron beam manipulation techniques.
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high quality Electron Beams from a helical inverse free Electron laser accelerator
Nature Communications, 2014Co-Authors: J Duris, J. B. Rosenzweig, P Musumeci, M Babzien, M Fedurin, K Kusche, J T Moody, Igor Pogorelsky, Mikhail Polyanskiy, Y SakaiAbstract:Electrons moving in strongly curved paths emit radiation that is used in free-Electron laser designs. Here, the authors demonstrate the inverse force principle, where a laser light field is used in a compact experimental design to accelerate Electrons to produce high-quality Electron Beams.
Martin Füllekrug - One of the best experts on this subject based on the ideXlab platform.
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relativistic Electron Beams above thunderclouds
Atmospheric Chemistry and Physics, 2011Co-Authors: Martin Füllekrug, E. M. D. Symbalisty, J. J. Colman, O. Van Der Velde, A. Odzimek, R A Rousseldupre, Olivier Chanrion, Serge Soula, A. J. BennettAbstract:Non-luminous relativistic Electron Beams above thunderclouds have been detected by the radio signals of low frequency 40-400 kHz which they radiate. The Electron Beams occur 2-9 ms after positive cloud-to-ground light- ning discharges at heights between 22-72 km above thun- derclouds. Intense positive lightning discharges can also cause sprites which occur either above or prior to the elec- tron beam. One Electron beam was detected without any lu- minous sprite which suggests that Electron Beams may also occur independently of sprites. Numerical simulations show that Beams of Electrons partially discharge the lightning elec- tric field above thunderclouds and thereby gain a mean en- ergy of 7 MeV to transport a total charge of 10 mC up- wards. The impulsive current 3◊ 10 3 Am 2 associated with relativistic Electron Beams above thunderclouds is di- rected downwards and needs to be considered as a novel ele- ment of the global atmospheric electric circuit.
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Relativistic Electron Beams above thunderclouds
Atmospheric Chemistry and Physics Discussions, 2011Co-Authors: Martin Füllekrug, Robert Roussel-dupré, E. M. D. Symbalisty, J. J. Colman, O. Van Der Velde, A. Odzimek, Olivier Chanrion, Serge Soula, A. J. Bennett, Victor P. PaskoAbstract:Abstract. Non-luminous relativistic Electron Beams above thunderclouds are detected by radio remote sensing with low frequency radio signals from 40–400 kHz. The Electron Beams occur 2–9 ms after positive cloud-to-ground lightning discharges at heights between 22–72 km above thunderclouds. The positive lightning discharges also cause sprites which occur either above or before the Electron beam. One Electron beam was detected without any luminous sprite occurrence which suggests that Electron Beams may also occur independently. Numerical simulations show that the beamed Electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of 7 MeV to transport a total charge of 10 mC upwards. The impulsive current associated with relativistic Electron Beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit.
