Pub Date : 2018-08-01DOI: 10.1109/AAC.2018.8659385
A. Lueangaramwong, O. Mohsen, P. Piot
A Direct-Current (DC) electron source test-stand to explore field-emission from various cathodes has been designed. The design also includes a provision to allow for laser-triggered field emission using a femtosecond laser source. The gun is instrumented to measure the beam transverse distribution, the transverse emittance, and I-V characteristic curves. The electrostatic design of the gun and multi-particle simulations of the beamline are presented and planned experiment discussed.
{"title":"Design of the Low-Energy DC Gun for Field-Emission Cathode Investigation","authors":"A. Lueangaramwong, O. Mohsen, P. Piot","doi":"10.1109/AAC.2018.8659385","DOIUrl":"https://doi.org/10.1109/AAC.2018.8659385","url":null,"abstract":"A Direct-Current (DC) electron source test-stand to explore field-emission from various cathodes has been designed. The design also includes a provision to allow for laser-triggered field emission using a femtosecond laser source. The gun is instrumented to measure the beam transverse distribution, the transverse emittance, and I-V characteristic curves. The electrostatic design of the gun and multi-particle simulations of the beamline are presented and planned experiment discussed.","PeriodicalId":339772,"journal":{"name":"2018 IEEE Advanced Accelerator Concepts Workshop (AAC)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122265087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-01DOI: 10.1109/AAC.2018.8659440
T. Xu, C. Jing, A. Kanareykin, P. Piot, J. Power
In beam-driven acceleration, drive bunches with ramped current profiles support enhanced transformer ratios which enable longer interaction lengths thereby increasing the energy gain associated with the witness bunch. The production of such tailored electron bunches can be accomplished via different beam shaping methods. One technique of particular interest, owing to its simplicity, consists in shaping the temporal profile of the laser pulse in photoemission sources. In this contribution we investigate, via a shape-optimization technique, the generation of a ramped bunch distribution using such a laser-shaping technique. Our study takes the example of the Argonne Wakefield Accelerator where a proof-of-principle experiment is being planned. We also discuss limitations associated with the laser shaping and possible improvements.
{"title":"Optimized Electron Bunch Current Distribution from a Radiofrequency Photo-Emission Source","authors":"T. Xu, C. Jing, A. Kanareykin, P. Piot, J. Power","doi":"10.1109/AAC.2018.8659440","DOIUrl":"https://doi.org/10.1109/AAC.2018.8659440","url":null,"abstract":"In beam-driven acceleration, drive bunches with ramped current profiles support enhanced transformer ratios which enable longer interaction lengths thereby increasing the energy gain associated with the witness bunch. The production of such tailored electron bunches can be accomplished via different beam shaping methods. One technique of particular interest, owing to its simplicity, consists in shaping the temporal profile of the laser pulse in photoemission sources. In this contribution we investigate, via a shape-optimization technique, the generation of a ramped bunch distribution using such a laser-shaping technique. Our study takes the example of the Argonne Wakefield Accelerator where a proof-of-principle experiment is being planned. We also discuss limitations associated with the laser shaping and possible improvements.","PeriodicalId":339772,"journal":{"name":"2018 IEEE Advanced Accelerator Concepts Workshop (AAC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122822034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-01DOI: 10.1109/AAC.2018.8659438
W. Kimura, D. S. Dhillon
Capillary discharges are used in laser plasma accelerators for providing the plasma medium that both forms the wakefield and guides the laser beam. For the latter, the radial parabolic density profile within the capillary channel can maintain a constant laser focus size along the capillary provided the proper conditions are satisfied between the laser beam waist size, channel diameter, and on-axis plasma density. This is referred to as matched guiding, but achieving this has been elusive and, instead, nonlinear self-focusing is typically utilized to achieve the required laser spot size. The Density-Customized Capillary (DC2) Discharge being developed is designed to enable true matched guiding without relying on nonlinear focusing. Furthermore, the goal is to accomplish this at the relatively low plasma densities needed by experiments, such as for the BErkeley Lab Laser Accelerator (BELLA) program. Our scheme also permits tapering the on-axis density along the capillary while maintaining the same matched spot size. Preliminary experimental results on the DC2 Discharge will be presented as well as demonstration of scaling to 1-meter-long capillary lengths.
{"title":"Density-Customized Capillary (DC2) Discharge","authors":"W. Kimura, D. S. Dhillon","doi":"10.1109/AAC.2018.8659438","DOIUrl":"https://doi.org/10.1109/AAC.2018.8659438","url":null,"abstract":"Capillary discharges are used in laser plasma accelerators for providing the plasma medium that both forms the wakefield and guides the laser beam. For the latter, the radial parabolic density profile within the capillary channel can maintain a constant laser focus size along the capillary provided the proper conditions are satisfied between the laser beam waist size, channel diameter, and on-axis plasma density. This is referred to as matched guiding, but achieving this has been elusive and, instead, nonlinear self-focusing is typically utilized to achieve the required laser spot size. The Density-Customized Capillary (DC2) Discharge being developed is designed to enable true matched guiding without relying on nonlinear focusing. Furthermore, the goal is to accomplish this at the relatively low plasma densities needed by experiments, such as for the BErkeley Lab Laser Accelerator (BELLA) program. Our scheme also permits tapering the on-axis density along the capillary while maintaining the same matched spot size. Preliminary experimental results on the DC2 Discharge will be presented as well as demonstration of scaling to 1-meter-long capillary lengths.","PeriodicalId":339772,"journal":{"name":"2018 IEEE Advanced Accelerator Concepts Workshop (AAC)","volume":"10 3-4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116160784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-01DOI: 10.1109/AAC.2018.8659442
C. Geddes, J. Shaw
Advances in and the physics of the acceleration of electrons and positrons using underdense plasma structures driven by lasers were the topics of presentations and discussions in Working Group 1. Such accelerators have demonstrated gradients several orders beyond conventional machines, with quasi-monoenergetic beams at MeV-GeV energies, making them attractive candidates for next generation accelerators and photon sources. The status, future direction, and research outlook are summarized and references given to group presentations.
{"title":"Summary of Working Group 1: Laser-Plasma Wakefield Acceleration","authors":"C. Geddes, J. Shaw","doi":"10.1109/AAC.2018.8659442","DOIUrl":"https://doi.org/10.1109/AAC.2018.8659442","url":null,"abstract":"Advances in and the physics of the acceleration of electrons and positrons using underdense plasma structures driven by lasers were the topics of presentations and discussions in Working Group 1. Such accelerators have demonstrated gradients several orders beyond conventional machines, with quasi-monoenergetic beams at MeV-GeV energies, making them attractive candidates for next generation accelerators and photon sources. The status, future direction, and research outlook are summarized and references given to group presentations.","PeriodicalId":339772,"journal":{"name":"2018 IEEE Advanced Accelerator Concepts Workshop (AAC)","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123584310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-01DOI: 10.1109/AAC.2018.8659408
Xiantao Cheng, R. Zgadzaj, A. Bernstein, M. LaBerge, J. Shaw, M. Downer
For the past decade, laser-plasma accelerators (LPAs) of millimeter to centimeter lengths have provided compact sources of nearly mono-energetic, highly directional electron bunches, with energies as high as 1 GeV. With the advent of petawatt scale lasers, these accelerators are now poised to go well beyond 1 GeV energies. In contrast to large-scale accelerator facilities, these LPA's will be compact devices, requiring compact electron spectrometers adapted to the unique properties of the LPA electron bunches. We report on a compact high-resolution spectrometer adapted to these conditions.
{"title":"Compact High-Resolution Multi-GeV Electron Spectrometer for PW-Laser-Driven Plasma Accelerators and Approximate Trajectory Method for Spectrum Analysis","authors":"Xiantao Cheng, R. Zgadzaj, A. Bernstein, M. LaBerge, J. Shaw, M. Downer","doi":"10.1109/AAC.2018.8659408","DOIUrl":"https://doi.org/10.1109/AAC.2018.8659408","url":null,"abstract":"For the past decade, laser-plasma accelerators (LPAs) of millimeter to centimeter lengths have provided compact sources of nearly mono-energetic, highly directional electron bunches, with energies as high as 1 GeV. With the advent of petawatt scale lasers, these accelerators are now poised to go well beyond 1 GeV energies. In contrast to large-scale accelerator facilities, these LPA's will be compact devices, requiring compact electron spectrometers adapted to the unique properties of the LPA electron bunches. We report on a compact high-resolution spectrometer adapted to these conditions.","PeriodicalId":339772,"journal":{"name":"2018 IEEE Advanced Accelerator Concepts Workshop (AAC)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123504714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-01DOI: 10.1109/AAC.2018.8659418
Yong Jiang, S. Shchelkunov, V. Teryaev, J. Hirshfield
New results are presented for the development of a 3 MW highly-efficient radio-frequency (RF) source at 1.3 GHz. The project's ultimate goal is to equip the existing tube with a partially grounded depressed collector in order to boost its efficiency to at least 73 %. The tests of this device in its original configuration are not yet completed. A limited 2-week campaign at Communication & Power Industries, LLC yielded 3MW at nearly 60% of efficiency in narrow 15 microsecond pulses. The next stage is to test the device and optimize it to achieve 62-63% in efficiency in the full pulse at 1.5 milliseconds. The preparations are almost complete to do these tests at SLAC National Accelerator Laboratory, End Station B. The results will be presented.
{"title":"O-MBK with Partially Grounded Depressed Collector","authors":"Yong Jiang, S. Shchelkunov, V. Teryaev, J. Hirshfield","doi":"10.1109/AAC.2018.8659418","DOIUrl":"https://doi.org/10.1109/AAC.2018.8659418","url":null,"abstract":"New results are presented for the development of a 3 MW highly-efficient radio-frequency (RF) source at 1.3 GHz. The project's ultimate goal is to equip the existing tube with a partially grounded depressed collector in order to boost its efficiency to at least 73 %. The tests of this device in its original configuration are not yet completed. A limited 2-week campaign at Communication & Power Industries, LLC yielded 3MW at nearly 60% of efficiency in narrow 15 microsecond pulses. The next stage is to test the device and optimize it to achieve 62-63% in efficiency in the full pulse at 1.5 milliseconds. The preparations are almost complete to do these tests at SLAC National Accelerator Laboratory, End Station B. The results will be presented.","PeriodicalId":339772,"journal":{"name":"2018 IEEE Advanced Accelerator Concepts Workshop (AAC)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123517453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-01DOI: 10.1109/AAC.2018.8659393
R. Yoder, Zumrad Kabilova, Benjamin Saeks, J. Jefferson, D. Lerner
Laser-powered acceleration structures such as dielectric laser accelerators (DLAs) require injection of a sub-micron-scale electron bunch to achieve high-quality, monoenergetic output beams. Field emission from an array of nanotips, followed by further acceleration and focusing, is a promising approach to achieving the requisite small beam sizes and near-relativistic energies for successful injection; however, conventional high-voltage sources are not easily integrated into dielectric structures. We have demonstrated that the strong electrostatic fields produced by pyroelectric crystals during heating and cooling can be used for field emission and pre-acceleration. We present a design, and proof-of-principle experimental results, for a low-energy injection module based on emission from nanotips within a hollow channel along the axis of a lithium niobate crystal. This mechanism is stageable and is predicted to deliver energies of several hundred keV in a few centimeters, suitable e.g. for DLA injection as well as potentially useful for industrial or medical applications.
{"title":"Near-Relativistic Electron Beam Production Using a Pyroelectric Crystal Array","authors":"R. Yoder, Zumrad Kabilova, Benjamin Saeks, J. Jefferson, D. Lerner","doi":"10.1109/AAC.2018.8659393","DOIUrl":"https://doi.org/10.1109/AAC.2018.8659393","url":null,"abstract":"Laser-powered acceleration structures such as dielectric laser accelerators (DLAs) require injection of a sub-micron-scale electron bunch to achieve high-quality, monoenergetic output beams. Field emission from an array of nanotips, followed by further acceleration and focusing, is a promising approach to achieving the requisite small beam sizes and near-relativistic energies for successful injection; however, conventional high-voltage sources are not easily integrated into dielectric structures. We have demonstrated that the strong electrostatic fields produced by pyroelectric crystals during heating and cooling can be used for field emission and pre-acceleration. We present a design, and proof-of-principle experimental results, for a low-energy injection module based on emission from nanotips within a hollow channel along the axis of a lithium niobate crystal. This mechanism is stageable and is predicted to deliver energies of several hundred keV in a few centimeters, suitable e.g. for DLA injection as well as potentially useful for industrial or medical applications.","PeriodicalId":339772,"journal":{"name":"2018 IEEE Advanced Accelerator Concepts Workshop (AAC)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125095362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-01DOI: 10.1109/AAC.2018.8659419
Yu-Hsin Chen, S. Steinke
Here we summarize the work presented during Working Group 6, Laser-Plasma Acceleration of Ions, at the 18th Advanced Accelerator Concepts Workshop in 2018.
{"title":"Summary of Working Group 6: Laser-Plasma Acceleration of Ions","authors":"Yu-Hsin Chen, S. Steinke","doi":"10.1109/AAC.2018.8659419","DOIUrl":"https://doi.org/10.1109/AAC.2018.8659419","url":null,"abstract":"Here we summarize the work presented during Working Group 6, Laser-Plasma Acceleration of Ions, at the 18th Advanced Accelerator Concepts Workshop in 2018.","PeriodicalId":339772,"journal":{"name":"2018 IEEE Advanced Accelerator Concepts Workshop (AAC)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127671267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-01DOI: 10.1109/AAC.2018.8659444
V. Pavlenko, H. Andrews, R. Aragonez, R. Fleming, Chengkun Huang, Dongsung Kim, T. Kwan, A. Piryatinski, E. Simakov
Field emission from nanocrystalline diamond and especially from diamond field emitters is known to have an onset at low electric fields of a few MV/m, although the discussion on the agreement of the results with the classical Fowler-Nordheim model is still pending. While measurements of pure photoemission from flat nanocrystalline diamond agree reasonably well with the 3-step photoemission model for the wide bandgap semiconductor with low electron affinity, we are not aware of systematic studies of photoemission in the ~0.1-5 MV/ m range, where the electron emission mechanism is expected to be affected by the Schottky effect and crossover with the field emission. In order to understand applicability of field enhanced photoemission from diamond to generation of bright coherent photo-gated electron beams suitable for dielectric laser accelerators, we have designed a system to measure spectral response (quantum efficiency vs wavelength) of ~mm-sized samples with up to 5 MV/ m electric field in the anode-cathode gap. The system is based on an incoherent Xe lamp-based tunable ultaviolet light source, therefore relatively large and dense diamond field emitter arrays are required for comparative studies of arrays versus flat nanocrystalline diamond samples. We present the results of our original measurements in the range between 195 nm and 270 nm. Potential schemes of laser-triggered photoemission from a single diamond field emitter tip are discussed in view of the obtained results.
{"title":"Field Assisted Photoemission from Nanocrystalline Diamond and Diamond Field Emitter Arrays","authors":"V. Pavlenko, H. Andrews, R. Aragonez, R. Fleming, Chengkun Huang, Dongsung Kim, T. Kwan, A. Piryatinski, E. Simakov","doi":"10.1109/AAC.2018.8659444","DOIUrl":"https://doi.org/10.1109/AAC.2018.8659444","url":null,"abstract":"Field emission from nanocrystalline diamond and especially from diamond field emitters is known to have an onset at low electric fields of a few MV/m, although the discussion on the agreement of the results with the classical Fowler-Nordheim model is still pending. While measurements of pure photoemission from flat nanocrystalline diamond agree reasonably well with the 3-step photoemission model for the wide bandgap semiconductor with low electron affinity, we are not aware of systematic studies of photoemission in the ~0.1-5 MV/ m range, where the electron emission mechanism is expected to be affected by the Schottky effect and crossover with the field emission. In order to understand applicability of field enhanced photoemission from diamond to generation of bright coherent photo-gated electron beams suitable for dielectric laser accelerators, we have designed a system to measure spectral response (quantum efficiency vs wavelength) of ~mm-sized samples with up to 5 MV/ m electric field in the anode-cathode gap. The system is based on an incoherent Xe lamp-based tunable ultaviolet light source, therefore relatively large and dense diamond field emitter arrays are required for comparative studies of arrays versus flat nanocrystalline diamond samples. We present the results of our original measurements in the range between 195 nm and 270 nm. Potential schemes of laser-triggered photoemission from a single diamond field emitter tip are discussed in view of the obtained results.","PeriodicalId":339772,"journal":{"name":"2018 IEEE Advanced Accelerator Concepts Workshop (AAC)","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120985676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-01DOI: 10.1109/AAC.2018.8659380
D. Cesar, P. Musumeci, J. England
Dielectric laser acceleration draws upon nanofabrication techniques to build photonic structures for high gradient electron acceleration. At the small spatial scales characteristic of these structures conventional accelerator techniques become ineffective at stabilizing the beam dynamics. Instead we propose a scheme to stabilize the motion by directly modulating the drive laser, in analogy to a radio-frequency-quadrupole. Here we present a design for a programmable ‘lattice’ being built at UCLA's Pegasus laboratory. The accelerator accepts an unmodulated 3.5 MeV electron beam and then bunches and accelerates the beam by 1.5 MeV over a distance of 2 cm.
{"title":"AII Optical Control of Beam Dynamics in a DLA","authors":"D. Cesar, P. Musumeci, J. England","doi":"10.1109/AAC.2018.8659380","DOIUrl":"https://doi.org/10.1109/AAC.2018.8659380","url":null,"abstract":"Dielectric laser acceleration draws upon nanofabrication techniques to build photonic structures for high gradient electron acceleration. At the small spatial scales characteristic of these structures conventional accelerator techniques become ineffective at stabilizing the beam dynamics. Instead we propose a scheme to stabilize the motion by directly modulating the drive laser, in analogy to a radio-frequency-quadrupole. Here we present a design for a programmable ‘lattice’ being built at UCLA's Pegasus laboratory. The accelerator accepts an unmodulated 3.5 MeV electron beam and then bunches and accelerates the beam by 1.5 MeV over a distance of 2 cm.","PeriodicalId":339772,"journal":{"name":"2018 IEEE Advanced Accelerator Concepts Workshop (AAC)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123997786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：