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Sökning: WFRF:(Welsch D.)

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1.
  • 2021
  • swepub:Mat__t
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2.
  • Glasbey, JC, et al. (författare)
  • 2021
  • swepub:Mat__t
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3.
  • 2021
  • swepub:Mat__t
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4.
  • Bravo, L, et al. (författare)
  • 2021
  • swepub:Mat__t
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5.
  • Tabiri, S, et al. (författare)
  • 2021
  • swepub:Mat__t
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8.
  • Walker, Anthony P, et al. (författare)
  • Horizon 2020 EuPRAXIA design study
  • 2017
  • Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 874:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The Horizon 2020 Project EuPRAXIA ("European Plasma Research Accelerator with eXcellence In Applications") is preparing a conceptual design report of a highly compact and cost-effective European facility with multi-GeV electron beams using plasma as the acceleration medium. The accelerator facility will be based on a laser and/or a beam driven plasma acceleration approach and will be used for photon science, high-energy physics (HEP) detector tests, and other applications such as compact X-ray sources for medical imaging or material processing. EuPRAXIA started in November 2015 and will deliver the design report in October 2019. EuPRAXIA aims to be included on the ESFRI roadmap in 2020.
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9.
  • Martel, I., et al. (författare)
  • An innovative Superconducting Recoil Separator for HIE-ISOLDE
  • 2023
  • Ingår i: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms. - : ELSEVIER. - 0168-583X .- 1872-9584. ; 541, s. 176-179
  • Tidskriftsartikel (refereegranskat)abstract
    • The ISOLDE Scientific Infrastructure at CERN offers a unique range of post-accelerated radioactive beams. The scientific program can be improved with the “Isolde Superconducting Recoil Separator” (ISRS), an innovative spectrometer able to deliver unprecedented (A, Z) resolution. In this paper we present an overview of the physics and ongoing technical developments.
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10.
  • Oellers, D., et al. (författare)
  • Polarizing a stored proton beam by spin flip?
  • 2009
  • Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 674:4-5, s. 269-275
  • Tidskriftsartikel (refereegranskat)abstract
    • We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin-flip cross section in low-energy electron–proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam.
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11.
  • Verra, L., et al. (författare)
  • Controlled Growth of the Self-Modulation of a Relativistic Proton Bunch in Plasma
  • 2022
  • Ingår i: Physical Review Accelerators and Beams. - : American Physical Society. - 2469-9888. ; 25:7
  • 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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12.
  • Welsch, Manuel, et al. (författare)
  • Smart and Just Grids for sub-Saharan Africa : Exploring options
  • 2013
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 20, s. 336-352
  • Tidskriftsartikel (refereegranskat)abstract
    • In 2009, an estimated 585 million people had no access to electricity services in sub-Saharan Africa. Unlike many other regions of the world, under current assumptions, that figure is expected to rise significantly to about 652 million by 2030-an unsustainable and unacceptable situation. Knowing of the intrinsic linkages between access to energy services and development, national governments and regional organisations have identified the urgent need for accelerated electrification rates. Some of the established and emerging concepts, systems and technologies grouped under the term 'Smart Grids' may offer an important contribution to achieving universal access to electricity. We argue that these Smart Grid advances may enable sub-Saharan African countries to leapfrog elements of traditional power systems and accelerate and improve electrification efforts. We introduce the notion of Just Grids to reflect the need for power systems to contribute towards equitable and inclusive economic and social development without marginalising the poor. The paper reviews the literature, and identifies specific options that could be implemented in sub-Saharan Africa. After selecting criteria that focus on potential impact as well as requirements for their implementation, a qualitative first-pass assessment of the potential of these options is made. This paper provides support for policy development, and suggests areas for further, more detailed research.
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14.
  • Bazilian, M., et al. (författare)
  • Accelerating the global transformation to 21st century power systems
  • 2013
  • Ingår i: Electricity Journal. - : Elsevier BV. - 1040-6190 .- 1873-6874. ; 26:6, s. 39-51
  • Tidskriftsartikel (refereegranskat)abstract
    • Nations and regions need to share lessons about the best ways to create enabling policies, regulations, and markets that get the most social benefit out of power systems and incent the necessary investments.
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15.
  • Habs, D., et al. (författare)
  • The REX-ISOLDE project
  • 2000
  • Ingår i: Hyperfine Interactions. - 0304-3843 .- 1572-9540. ; 129:1-4, s. 43-66
  • Tidskriftsartikel (refereegranskat)abstract
    • The Radioactive Beam Experiment REX-ISOLDE [1-3] is a pilot experiment at ISOLDE (CERN) testing the new concept of post acceleration of radioactive ion beams by using charge breeding of the ions in a high charge state ion source and the efficient acceleration of the highly charged ions in a short LINAC using modern ion accelerator structures. In order to prepare the ions for the experiments singly charged radioactive ions from the on-line mass separator ISOLDE will be cooled and bunched in a Penning trap, charge bred in an electron beam ion source (EBIS) and finally accelerated in the LINAC. The LINAC consists of a radiofrequency quadrupole (RFQ) accelerator, which accelerates the ions up to 0.3 MeV/u, an interdigital H-type (IH) structure with a final energy between 1.1 and 1.2 MeV/u and three seven gap resonators, which allow the variation of the final energy. With an energy of the radioactive beams between 0.8 MeV/u and 2.2 MeV/u a wide range of experiments in the field of nuclear spectroscopy, astrophysics and solid state physics will be addressed by REX-ISOLDE.
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16.
  • Welsch, Manuel, et al. (författare)
  • Adding value with CLEWS - Modelling the energy system and its interdependencies for Mauritius
  • 2014
  • Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 113, s. 1434-1445
  • Tidskriftsartikel (refereegranskat)abstract
    • Climate, Energy, Water and Land-use Systems (CLEWS) are closely integrated. Yet, most related decision and policy making occurs in disparate institutional entities, informed by relatively disconnected assessments of the individual resource systems. This paper presents the added value of an integrated analytical assessment approach. In doing so, it explicitly values various interdependencies and interactions between CLEWS primarily from an energy sector perspective. The island state of Mauritius was identified as a useful case study given its diverse climate, its increasing water stresses, and its policy focus on reshaping agricultural land-use and reducing fossil fuel imports. Several scenarios to 2030 were defined and analysed to demonstrate the tensions around the CLEWS nexus. Results from an assessment of the energy system with no modelled interlinkages to land-use, energy and water systems are first presented. Then, these are compared to those from an integrated CLEWS assessment. This serves to highlight important dynamics that would have been overlooked without such a systems approach. As an example, the added value of this approach is clearly demonstrated when rainfall reductions are taken into account, and where future land-use changes might occur.
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17.
  • Dabrowski, A. E., et al. (författare)
  • Measuring the bunch frequency multiplication at CTF3
  • 2010
  • Konferensbidrag (refereegranskat)abstract
    • The CTF3 facility is being built and commissioned by an international collaboration in order to test the feasibility of the proposed CLIC drive beam generation scheme. Central to this scheme is the use of RF deflectors to inject bunches into a Delay Loop and a Combiner Ring, in order to transform the initial bunch spacing of 1.5 GHz from the linac to a final bunch spacing of 12 GHz. The optimization procedure relies on several steps. The active length of each ring is carefully adjusted to within a few millimeters accuracy using a two‐period undulator. The transverse optics of the machine must be set-up in a way so as to ensure the beam isochronicity. Diagnostics based on optical streak cameras and RF power measurements have been designed to measure the longitudinal behaviour of the beam during the combination. This paper presents their performance and highlights recent measurements.
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18.
  • Dabrowski, A. E., et al. (författare)
  • Measuring the bunch frequency multiplication at the 3rd CLIC Test Facility
  • 2012
  • Ingår i: Journal of Instrumentation. - 1748-0221. ; 7, s. P01005-
  • Tidskriftsartikel (refereegranskat)abstract
    • The CLIC Test Facility 3 (CTF3) is being built and commissioned by an international collaboration to test the feasibility of the proposed Compact Linear Collider (CLIC) drive beam generation scheme. Central to this scheme is the use of RF deflectors to inject bunches into a delay loop and a combiner ring, in order to transform the initial bunch frequency of 1.5 GHz from the linac to a final bunch frequency of 12 GHz. To do so, the machine's transverse optics must be tuned to ensure beam isochronicity and each ring's length can finally be adjusted with wiggler magnets to a sub millimeter path length accuracy. Diagnostics based on optical streak camera and RF power measurements, in particular frequency bands, have been designed to measure the longitudinal behaviour of the beam during the combination. This paper presents the diagnostics and recent commissioning measurements.
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20.
  • Loh, Z-H, et al. (författare)
  • Observation of the fastest chemical processes in the radiolysis of water
  • 2020
  • Ingår i: Science. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075 .- 1095-9203. ; 367:6474, s. 179-182
  • Tidskriftsartikel (refereegranskat)abstract
    • Elementary processes associated with ionization of liquid water provide a framework for understanding radiation-matter interactions in chemistry and biology. Although numerous studies have been conducted on the dynamics of the hydrated electron, its partner arising from ionization of liquid water, H2O+, remains elusive. We used tunable femtosecond soft x-ray pulses from an x-ray free electron laser to reveal the dynamics of the valence hole created by strong-field ionization and to track the primary proton transfer reaction giving rise to the formation of OH. The isolated resonance associated with the valence hole (H2O+/OH) enabled straightforward detection. Molecular dynamics simulations revealed that the x-ray spectra are sensitive to structural dynamics at the ionization site. We found signatures of hydrated-electron dynamics in the x-ray spectrum.
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21.
  • Nechaeva, T., et al. (författare)
  • Hosing of a Long Relativistic Particle Bunch in Plasma
  • 2024
  • Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 132:7
  • 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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22.
  • Shivakumar, Abhishek, et al. (författare)
  • Need for Reliability and Measuring Its Cost
  • 2017
  • Ingår i: Europe's Energy Transition - Insights for Policy Making. - : Elsevier. - 9780128098066 - 9780128099032 ; , s. 207-218
  • Bokkapitel (refereegranskat)abstract
    • At present, power supply in the EU is characterized by a relatively high reliability. It should, however, not be taken for granted given the increasing shares of variable RES. Choosing the socioeconomically optimal level of reliability to aim for requires a thorough understanding of the socioeconomic costs of electricity supply interruptions. This chapter provides guidance on how to measure the consequences of supply interruptions and thus determine the value of electricity supply security.
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23.
  • Shivakumar, Abhishek, et al. (författare)
  • Valuing blackouts and lost leisure : Estimating electricity interruption costs for households across the European Union
  • 2017
  • Ingår i: Energy Research & Social Science. - : Elsevier. - 2214-6296 .- 2214-6326. ; 34, s. 39-48
  • Tidskriftsartikel (refereegranskat)abstract
    • Security of power supply is a crucial element of energy system planning and policy. However, the value that society places on it is not clearly known. Several previous studies estimate the cost of electricity interruptions for individual European Union (EU) Member States – as the Value of Lost Load (VoLL). In this paper, we use a production-function approach to estimate the average annual VoLL for households in all twenty-eight EU Member States. This is the first time that a unified approach has been applied for a single year across the EU. VoLL is further presented on an hourly basis to better understand the impact of the time at which the interruption occurs. Finally, we analyse the impact of ‘substitutability factor’ – the proportion of household activities that are electricity-dependent – on the VoLL. Results from this study show that the differences in VoLL between EU Member States is significantly large, ranging from 3.2 €/kWh in Bulgaria to 15.8 €/kWh in the Netherlands. The annual average VoLL for the EU was calculated to be 8.7 €/kWh. Results from this study can be used to inform key areas of European energy policy and market design.
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24.
  • Taliotis, Constantinos, et al. (författare)
  • Grand Inga to power Africa : Hydropower development scenarios to 2035
  • 2014
  • Ingår i: Energy Strategy Reviews. - : Elsevier BV. - 2211-467X .- 2211-4688. ; 4, s. 1-10
  • Tidskriftsartikel (refereegranskat)abstract
    • The vision of harnessing the Congo River's immense flow to generate power for the African continent has existed in the agenda of energy planners and politicians for nearly a century. However after the installations of Inga I in 1972 and Inga II in 1982, progress came to a standstill. Recently though the larger aspirations of Grand Inga seem to be moving forward again. Construction of Inga III low-head is set to commence in 2015 with a projected capacity of 4755MW, of which 2500MW are contracted for the South African market. Upon completion, the total capacity of Grand Inga could reach 42GW. In this paper, we present scenario-driven results of a Sub-Saharan African-focused partial-equilibrium energy model related to the further development of the project. The analysis is presented to show the broad range of possible energy futures related to this project, without taking into deep consideration the admittedly important issues related to governance, environmental impacts or social tensions. Scenarios are developed to assess the energy outlook of the Central African power pool, in which Grand Inga is located, and the exchange of electricity between regions when the project is completed. The project has the potential to cover the increasing needs for power in this power pool and provide electricity exports to other regions; primarily Southern and Western Africa in a high demand scenario and Southern and Northern Africa in a low demand scenario.
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25.
  • Verra, L., et al. (författare)
  • Development of the self-modulation instability of a relativistic proton bunch in plasma
  • 2023
  • Ingår i: Physics of Plasmas. - : American Institute of Physics (AIP). - 1070-664X .- 1089-7674. ; 30:8
  • 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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26.
  • Welsch, Manuel, et al. (författare)
  • Europe's energy transition : Insights for policy making
  • 2017
  • Bok (övrigt vetenskapligt/konstnärligt)abstract
    • Europe's Energy Transition: Insights for Policy Making looks at the availability and cost of accessing energy and how it significantly affects economic growth and competitiveness in global markets. The results in this book, from a European Commission (EC) financed project by INSIGHT_E, provide an overview of the most recent analyses, focusing on energy markets and their implications for society. Designed to inform European policymaking, elements of this book will be integrated into upcoming EC policies, giving readers invaluable insights into the cost and availability of energy, the effect of price increases affecting vulnerable consumer groups, and current topics of interest to the EC and ongoing energy debate. INSIGHT_E provides decision-makers with unbiased policy advice and insights on the latest developments, including an assessment of their potential impact. Presents answers to strategic questions posed by the European Commission. Coherently assesses the energy transition, from policies to energy supply, markets, system requirements, and consumer needs. Informed the EC "Clean Energy for All Europeans" package from end of 2016, e.g., regarding aspects of energy poverty. Endorsed by thought leaders from within and outside of Europe, including utilities, energy agencies, research institutes, journal editors, think tanks, and the European Commission.
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