| 1. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 3. |
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| 4. |
- Matteini, L., et al.
(författare)
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Solar Orbiter's encounter with the tail of comet C/2019 Y4 (ATLAS) : Magnetic field draping and cometary pick-up ion waves
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 656
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Tidskriftsartikel (refereegranskat)abstract
- Context. Solar Orbiter is expected to have flown close to the tail of comet C/2019 Y4 (ATLAS) during the spacecraft’s first perihelion in June 2020. Models predict a possible crossing of the comet tails by the spacecraft at a distance from the Sun of approximately 0.5 AU.Aims. This study is aimed at identifying possible signatures of the interaction of the solar wind plasma with material released by comet ATLAS, including the detection of draped magnetic field as well as the presence of cometary pick-up ions and of ion-scale waves excited by associated instabilities. This encounter provides us with the first opportunity of addressing such dynamics in the inner Heliosphere and improving our understanding of the plasma interaction between comets and the solar wind.Methods. We analysed data from all in situ instruments on board Solar Orbiter and compared their independent measurements in order to identify and characterize the nature of structures and waves observed in the plasma when the encounter was predicted.Results. We identified a magnetic field structure observed at the start of 4 June, associated with a full magnetic reversal, a local deceleration of the flow and large plasma density, and enhanced dust and energetic ions events. The cross-comparison of all these observations support a possible cometary origin for this structure and suggests the presence of magnetic field draping around some low-field and high-density object. Inside and around this large scale structure, several ion-scale wave-forms are detected that are consistent with small-scale waves and structures generated by cometary pick-up ion instabilities.Conclusions. Solar Orbiter measurements are consistent with the crossing through a magnetic and plasma structure of cometary origin embedded in the ambient solar wind. We suggest that this corresponds to the magnetotail of one of the fragments of comet ATLAS or to a portion of the tail that was previously disconnected and advected past the spacecraft by the solar wind.
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| 5. |
- Verra, L., et al.
(författare)
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Development of the self-modulation instability of a relativistic proton bunch in plasma
- 2023
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Ingår i: Physics of Plasmas. - : American Institute of Physics (AIP). - 1070-664X .- 1089-7674. ; 30:8
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Tidskriftsartikel (refereegranskat)abstract
- Self-modulation is a beam-plasma instability that is useful to drive large-amplitude wakefields with bunches much longer than the plasma skin depth. We present experimental results showing that, when increasing the ratio between the initial transverse size of the bunch and the plasma skin depth, the instability occurs later along the bunch, or not at all, over a fixed plasma length because the amplitude of the initial wakefields decreases. We show cases for which self-modulation does not develop, and we introduce a simple model discussing the conditions for which it would not occur after any plasma length. Changing bunch size and plasma electron density also changes the growth rate of the instability. We discuss the impact of these results on the design of a particle accelerator based on the self-modulation instability seeded by a relativistic ionization front, such as the future upgrade of the Advanced WAKefield Experiment.
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| 6. |
- Verra, L., et al.
(författare)
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Filamentation of a relativistic proton bunch in plasma
- 2024
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Ingår i: Physical review. E. - : American Physical Society. - 2470-0045 .- 2470-0053. ; 109:5
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Tidskriftsartikel (refereegranskat)abstract
- We show in experiments that a long, underdense, relativistic proton bunch propagating in plasma undergoes the oblique instability, which we observe as filamentation. We determine a threshold value for the ratio between the bunch transverse size and plasma skin depth for the instability to occur. At the threshold, the outcome of the experiment alternates between filamentation and self-modulation instability (evidenced by longitudinal modulation into microbunches). Time-resolved images of the bunch density distribution reveal that filamentation grows to an observable level late along the bunch, confirming the spatiotemporal nature of the instability. We provide a rough estimate of the amplitude of the magnetic field generated in the plasma by the instability and show that the associated magnetic energy increases with plasma density.
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| 7. |
- Nechaeva, T., et al.
(författare)
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Hosing of a Long Relativistic Particle Bunch in Plasma
- 2024
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 132:7
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Tidskriftsartikel (refereegranskat)abstract
- Experimental results show that hosing of a long particle bunch in plasma can be induced by wakefields driven by a short, misaligned preceding bunch. Hosing develops in the plane of misalignment, selfmodulation in the perpendicular plane, at frequencies close to the plasma electron frequency, and are reproducible. Development of hosing depends on misalignment direction, its growth on misalignment extent and on proton bunch charge. Results have the main characteristics of a theoretical model, are relevant to other plasma -based accelerators and represent the first characterization of hosing.
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| 8. |
- Verra, L., et al.
(författare)
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Controlled Growth of the Self-Modulation of a Relativistic Proton Bunch in Plasma
- 2022
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Ingår i: Physical Review Accelerators and Beams. - : American Physical Society. - 2469-9888. ; 25:7
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Tidskriftsartikel (refereegranskat)abstract
- A long, narrow, relativistic charged particle bunch propagating in plasma is subject to the self -modulation (SM) instability. We show that SM of a proton bunch can be seeded by the wakefields driven by a preceding electron bunch. SM timing reproducibility and control are at the level of a small fraction of the modulation period. With this seeding method, we independently control the amplitude of the seed wakefields with the charge of the electron bunch and the growth rate of SM with the charge of the proton bunch. Seeding leads to larger growth of the wakefields than in the instability case.
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| 9. |
- Deans, Andrew R, et al.
(författare)
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Finding Our Way through Phenotypes.
- 2015
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Ingår i: PLoS Biology. - : Public Library of Science (PLoS). - 1545-7885. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Despite a large and multifaceted effort to understand the vast landscape of phenotypic data, their current form inhibits productive data analysis. The lack of a community-wide, consensus-based, human- and machine-interpretable language for describing phenotypes and their genomic and environmental contexts is perhaps the most pressing scientific bottleneck to integration across many key fields in biology, including genomics, systems biology, development, medicine, evolution, ecology, and systematics. Here we survey the current phenomics landscape, including data resources and handling, and the progress that has been made to accurately capture relevant data descriptions for phenotypes. We present an example of the kind of integration across domains that computable phenotypes would enable, and we call upon the broader biology community, publishers, and relevant funding agencies to support efforts to surmount today's data barriers and facilitate analytical reproducibility.
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| 10. |
- Gangopadhyay, S., et al.
(författare)
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C-60 submonolayers on the Si(111)-(7 x 7) surface: Does a mixture of physisorbed and chemisorbed states exist?
- 2009
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028. ; 603:18, s. 2896-2901
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Tidskriftsartikel (refereegranskat)abstract
- We have carried out a combined X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy(UPS), and scanning tunnelling microscopy (STM) study of the C-60-Si(1 1 1) interaction where the XPS/UPS spectrometer and STM are integrated on a single UHV system. This enables a direct comparison of the XPS/UPS spectra with the STM data and eliminates any uncertainty in C-60 coverage measurements. X-ray standing wave measurements and density functional theory calculations have been used to support and interpret the results of the XPS/UPS/STM experiments. Our data conclusively rule out models of C-60 adsorption which involve a mixture of physisorbed and chemisorbed molecules [K. Sakamoto, et al., Phys. Rev. B 60 (1999) 2579]. Instead, we find that all molecules, up to 1 monolayer coverage, bond to the surface via Si-C bonds which are predominantly of covalent character. (C) 2009 Elsevier B.V. All rights reserved.
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