Pub Date : 2015-10-05DOI: 10.1103/PHYSREVSTAB.18.101301
Jonathan C. Wong, B. Logan, Simon S. Yu
{"title":"Conceptual design of heavy ion beam compression using a wedge","authors":"Jonathan C. Wong, B. Logan, Simon S. Yu","doi":"10.1103/PHYSREVSTAB.18.101301","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.101301","url":null,"abstract":"","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79427927","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 : 2015-09-30DOI: 10.1103/PHYSREVSTAB.18.091302
T. Alekhina, A. Tyukhtin, A. A. Grigoreva
We analyze the electromagnetic field of a charged particle that uniformly moves in a circular waveguide and crosses a boundary between a dielectric medium, which possesses frequency dispersion of a resonant type, and a vacuum area. The investigation of the waveguide mode components is analytically and numerically performed. It is shown that Cherenkov radiation (CR) can penetrate through the boundary, and Cherenkov-transition radiation (CTR) can be excited in the vacuum region. The conditions for this effect are obtained. It is shown that the CTR can be composed of a single mode (compared with the CTR in a nondispersive dielectric, which is multimode). The amplitude of the CTR is comparable to the amplitude of CR in an extensive range of parameters. The considered effect can be used to generate intense quasimonochromatic radiation.
{"title":"Cherenkov-transition radiation in a waveguide partly filled with a resonance dispersion medium","authors":"T. Alekhina, A. Tyukhtin, A. A. Grigoreva","doi":"10.1103/PHYSREVSTAB.18.091302","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.091302","url":null,"abstract":"We analyze the electromagnetic field of a charged particle that uniformly moves in a circular waveguide and crosses a boundary between a dielectric medium, which possesses frequency dispersion of a resonant type, and a vacuum area. The investigation of the waveguide mode components is analytically and numerically performed. It is shown that Cherenkov radiation (CR) can penetrate through the boundary, and Cherenkov-transition radiation (CTR) can be excited in the vacuum region. The conditions for this effect are obtained. It is shown that the CTR can be composed of a single mode (compared with the CTR in a nondispersive dielectric, which is multimode). The amplitude of the CTR is comparable to the amplitude of CR in an extensive range of parameters. The considered effect can be used to generate intense quasimonochromatic radiation.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90385804","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 : 2015-09-30DOI: 10.1103/PHYSREVSTAB.18.090704
K. Hacker, Shaukat Khan, R.Molo
Measurements of the longitudinal phase-space distributions of electron bunches seeded with an external laser were done in order to study the impact of collective effects on seeded microbunches in free-electron lasers. When the collective effects of Coulomb forces in a drift space and coherent synchrotron radiation in a chicane are considered, velocity bunching of a seeded microbunch appears to be a viable alternative to compression with a magnetic chicane under high-gain harmonic generation seeding conditions. Measurements of these effects on seeded electron microbunches were performed with a rf deflecting structure and a dipole magnet which streak out the electron bunch for single-shot images of the longitudinal phase-space distribution. Particle tracking simulations in 3D predicted the compression dynamics of the seeded microbunches with collective effects.
{"title":"Measurements and simulations of seeded electron microbunches with collective effects","authors":"K. Hacker, Shaukat Khan, R.Molo","doi":"10.1103/PHYSREVSTAB.18.090704","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.090704","url":null,"abstract":"Measurements of the longitudinal phase-space distributions of electron bunches seeded with an external laser were done in order to study the impact of collective effects on seeded microbunches in free-electron lasers. When the collective effects of Coulomb forces in a drift space and coherent synchrotron radiation in a chicane are considered, velocity bunching of a seeded microbunch appears to be a viable alternative to compression with a magnetic chicane under high-gain harmonic generation seeding conditions. Measurements of these effects on seeded electron microbunches were performed with a rf deflecting structure and a dipole magnet which streak out the electron bunch for single-shot images of the longitudinal phase-space distribution. Particle tracking simulations in 3D predicted the compression dynamics of the seeded microbunches with collective effects.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79837580","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 : 2015-09-29DOI: 10.1103/PHYSREVSTAB.18.090703
A. Smirnov, R. Agustsson, W. Berg, S. Boucher, J. Dooling, T. Campese, Y. Chen, L. Erwin, B. Jacobson, J. Hartzell, R. Lindberg, A. Murokh, F.H.O'Shea, E. Spranza, S. Pasky, M. Ruelas, N. Sereno, Y. Sun, A. Zholents
Compact THz source based on low energy electron and a planar corrugated structure was demonstrated experimentally.
实验证明了基于低能电子和平面波纹结构的紧凑太赫兹源。
{"title":"Observation of a variable sub-THz radiation driven by a low energy electron beam from a thermionic rf electron gun","authors":"A. Smirnov, R. Agustsson, W. Berg, S. Boucher, J. Dooling, T. Campese, Y. Chen, L. Erwin, B. Jacobson, J. Hartzell, R. Lindberg, A. Murokh, F.H.O'Shea, E. Spranza, S. Pasky, M. Ruelas, N. Sereno, Y. Sun, A. Zholents","doi":"10.1103/PHYSREVSTAB.18.090703","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.090703","url":null,"abstract":"Compact THz source based on low energy electron and a planar corrugated structure was demonstrated experimentally.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73013618","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 : 2015-09-29DOI: 10.1103/PHYSREVSTAB.18.094701
J. Garland, R. Appleby, H. Owen, S. Tygier
In this paper we present a new lattice design for a 30–350 MeV scaling fixed-field alternating gradient accelerator for proton therapy and tomography—NORMA (NOrmal-conducting Racetrack Medical Accelerator). The energy range allows the realization of proton computed tomography and utilizes normal conducting magnets in both a conventional circular ring option and a novel racetrack configuration, both designed using advanced optimization algorithms we have developed in PyZgoubi. Both configurations consist of ten focusing-defocusing-focusing triplet cells and operate in the second stability region of Hills equation. The ring configuration has a circumference of 60 m, a peak magnetic field seen by the beam of <1.6 T, a maximum horizontal orbit excursion of 44 cm and a dynamic aperture of 68 mm mrad— determined using a novel dynamic aperture (DA) calculation technique. The racetrack alternative is realized by adding magnet-free drift space in between cells at two opposing points in the ring, to facilitate injection and extraction. Our racetrack design has a total magnet-free straight lengths of 4.9 m, a circumference of 71 m, a peak magnetic field seen by the beam of <1.74 T, a maximum horizontal orbit excursion of 50 cm and a DA of 58 mm mrad. A transverse magnet misalignment model is also presented for the ring and racetrack configurations where the DA remains above 40 mm mrad for randomly misaligned error distributions with a standard deviation up to 100 μm.
本文提出了一种用于质子治疗和层析成像的30-350 MeV尺度固定场交变梯度加速器的新晶格设计- norma(正常传导赛道医学加速器)。该能量范围允许实现质子计算机断层扫描，并在传统的环形选项和新颖的赛道配置中使用正常导电磁铁，两者都使用我们在PyZgoubi开发的先进优化算法设计。这两种结构都由十个聚焦-散焦-聚焦三重单元组成，并在希尔斯方程的第二稳定区工作。环形结构的周长为60 m，波束的峰值磁场<1.6 T，最大水平轨道偏移44 cm，动态孔径为68 mm，采用一种新的动态孔径(DA)计算技术确定。赛道替代方案是通过在环中两个相对点的细胞之间增加无磁漂移空间来实现的，以方便注射和提取。我们设计的赛道总无磁直线长度为4.9 m，周长为71 m，波束看到的峰值磁场<1.74 T，最大水平轨道偏移50 cm, DA为58 mm mrad。此外，本文还建立了环形和赛道结构的横向磁体失调模型，其中DA保持在40 mm mrad以上，随机失调误差分布的标准偏差可达100 μm。
{"title":"Normal-conducting scaling fixed field alternating gradient accelerator for proton therapy","authors":"J. Garland, R. Appleby, H. Owen, S. Tygier","doi":"10.1103/PHYSREVSTAB.18.094701","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.094701","url":null,"abstract":"In this paper we present a new lattice design for a 30–350 MeV scaling fixed-field alternating gradient accelerator for proton therapy and tomography—NORMA (NOrmal-conducting Racetrack Medical Accelerator). The energy range allows the realization of proton computed tomography and utilizes normal conducting magnets in both a conventional circular ring option and a novel racetrack configuration, both designed using advanced optimization algorithms we have developed in PyZgoubi. Both configurations consist of ten focusing-defocusing-focusing triplet cells and operate in the second stability region of Hills equation. The ring configuration has a circumference of 60 m, a peak magnetic field seen by the beam of <1.6 T, a maximum horizontal orbit excursion of 44 cm and a dynamic aperture of 68 mm mrad— determined using a novel dynamic aperture (DA) calculation technique. The racetrack alternative is realized by adding magnet-free drift space in between cells at two opposing points in the ring, to facilitate injection and extraction. Our racetrack design has a total magnet-free straight lengths of 4.9 m, a circumference of 71 m, a peak magnetic field seen by the beam of <1.74 T, a maximum horizontal orbit excursion of 50 cm and a DA of 58 mm mrad. A transverse magnet misalignment model is also presented for the ring and racetrack configurations where the DA remains above 40 mm mrad for randomly misaligned error distributions with a standard deviation up to 100 μm.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83802733","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 : 2015-09-28DOI: 10.1103/PHYSREVSTAB.18.090702
R. Lindberg, Kwang-je Kim
{"title":"Compact representations of partially coherent undulator radiation suitable for wave propagation","authors":"R. Lindberg, Kwang-je Kim","doi":"10.1103/PHYSREVSTAB.18.090702","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.090702","url":null,"abstract":"","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1103/PHYSREVSTAB.18.090702","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72540094","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 : 2015-09-28DOI: 10.1103/PHYSREVSTAB.18.092801
F. Qiu, S. Michizono, T. Miura, Toshihiro Matsumoto, M. Omet, Basuki Wibowo Sigit
A disturbance observer (DOB)-based control for a digital low-level radio-frequency (LLRF) system in a compact energy recovery linac (cERL) at KEK has been developed. The motivation for this control approach is to compensate for or suppress the disturbance signal in the rf system such as beam loading, power supply ripples, and microphonics. Disturbance signals in specified frequency ranges were observed and reconstructed accurately in the field-programmable gate array and were then removed in the feedforward model in real time. The key component in this DOB controller is a disturbance observer, which includes the inverse mathematical model of the rf plant. In this paper, we have designed a DOB control-based approach in order to improve the LLRF system performance in disturbance rejection. We have confirmed this approach in the cERL beam commissioning.
{"title":"Application of disturbance observer-based control in low-level radio-frequency system in a compact energy recovery linac at KEK","authors":"F. Qiu, S. Michizono, T. Miura, Toshihiro Matsumoto, M. Omet, Basuki Wibowo Sigit","doi":"10.1103/PHYSREVSTAB.18.092801","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.092801","url":null,"abstract":"A disturbance observer (DOB)-based control for a digital low-level radio-frequency (LLRF) system in a compact energy recovery linac (cERL) at KEK has been developed. The motivation for this control approach is to compensate for or suppress the disturbance signal in the rf system such as beam loading, power supply ripples, and microphonics. Disturbance signals in specified frequency ranges were observed and reconstructed accurately in the field-programmable gate array and were then removed in the feedforward model in real time. The key component in this DOB controller is a disturbance observer, which includes the inverse mathematical model of the rf plant. In this paper, we have designed a DOB control-based approach in order to improve the LLRF system performance in disturbance rejection. We have confirmed this approach in the cERL beam commissioning.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79950442","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 : 2015-09-15DOI: 10.1103/PHYSREVSTAB.18.092001
D. Alesini, A. Battisti, M. Ferrario, L. Foggetta, V. Lollo, L. Ficcadenti, V. Pettinacci, S. Custodio, E. Pirez, P. Musumeci, L. Palumbo
High gradient rf photoguns have been a key development to enable several applications of high quality electron beams. They allow the generation of beams with very high peak current and low transverse emittance, satisfying the tight demands for free-electron lasers, energy recovery linacs, Compton/Thomson sources and high-energy linear colliders. In the present paper we present the design of a new rf photogun recently developed in the framework of the SPARC_LAB photoinjector activities at the laboratories of the National Institute of Nuclear Physics in Frascati (LNF-INFN, Italy). This design implements several new features from the electromagnetic point of view and, more important, a novel technology for its realization that does not involve any brazing process. From the electromagnetic point of view the gun presents high mode separation, low peak surface electric field at the iris and minimized pulsed heating on the coupler. For the realization, we have implemented a novel fabrication design that, avoiding brazing, strongly reduces the cost, the realization time and the risk of failure. Details on the electromagnetic design, low power rf measurements and high power radiofrequency and beam tests performed at the University of California in Los Angeles (UCLA) are discussed in the paper.
{"title":"New technology based on clamping for high gradient radio frequency photogun","authors":"D. Alesini, A. Battisti, M. Ferrario, L. Foggetta, V. Lollo, L. Ficcadenti, V. Pettinacci, S. Custodio, E. Pirez, P. Musumeci, L. Palumbo","doi":"10.1103/PHYSREVSTAB.18.092001","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.092001","url":null,"abstract":"High gradient rf photoguns have been a key development to enable several applications of high quality electron beams. They allow the generation of beams with very high peak current and low transverse emittance, satisfying the tight demands for free-electron lasers, energy recovery linacs, Compton/Thomson sources and high-energy linear colliders. In the present paper we present the design of a new rf photogun recently developed in the framework of the SPARC_LAB photoinjector activities at the laboratories of the National Institute of Nuclear Physics in Frascati (LNF-INFN, Italy). This design implements several new features from the electromagnetic point of view and, more important, a novel technology for its realization that does not involve any brazing process. From the electromagnetic point of view the gun presents high mode separation, low peak surface electric field at the iris and minimized pulsed heating on the coupler. For the realization, we have implemented a novel fabrication design that, avoiding brazing, strongly reduces the cost, the realization time and the risk of failure. Details on the electromagnetic design, low power rf measurements and high power radiofrequency and beam tests performed at the University of California in Los Angeles (UCLA) are discussed in the paper.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84211410","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 : 2015-09-14DOI: 10.1103/PHYSREVSTAB.18.091003
T. Davenne, O. Caretta, C. Densham, M. Fitton, P. Loveridge, P. Hurh, R. Zwaska, J. Hylen, V. Papadimitriou
The Long Baseline Neutrino Facility (LBNF, formerly the Long Baseline Neutrino Experiment) is under design as a next generation neutrino oscillation experiment, with primary objectives to search for CP violation in the leptonic sector, to determine the neutrino mass hierarchy and to provide a precise measurement of θ 23. The facility will generate a neutrino beam at Fermilab by the interaction of a proton beam with a target material. At the ultimate anticipated proton beam power of 2.3 MW the target material must dissipate a heat load of between 10 and 25 kW depending on the target size. This paper presents a target concept based on an array of spheres and compares it to a cylindrical monolithic target such as that which currently operates at the T2K facility. Thus simulation results show that the proposed technology offers efficient cooling and lower stresses whilst delivering a neutrino production comparable with that of a conventional solid cylindrical target.
{"title":"Segmented beryllium target for a 2 MW super beam facility","authors":"T. Davenne, O. Caretta, C. Densham, M. Fitton, P. Loveridge, P. Hurh, R. Zwaska, J. Hylen, V. Papadimitriou","doi":"10.1103/PHYSREVSTAB.18.091003","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.091003","url":null,"abstract":"The Long Baseline Neutrino Facility (LBNF, formerly the Long Baseline Neutrino Experiment) is under design as a next generation neutrino oscillation experiment, with primary objectives to search for CP violation in the leptonic sector, to determine the neutrino mass hierarchy and to provide a precise measurement of θ 23. The facility will generate a neutrino beam at Fermilab by the interaction of a proton beam with a target material. At the ultimate anticipated proton beam power of 2.3 MW the target material must dissipate a heat load of between 10 and 25 kW depending on the target size. This paper presents a target concept based on an array of spheres and compares it to a cylindrical monolithic target such as that which currently operates at the T2K facility. Thus simulation results show that the proposed technology offers efficient cooling and lower stresses whilst delivering a neutrino production comparable with that of a conventional solid cylindrical target.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89493579","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 : 2015-09-11DOI: 10.1103/PHYSREVSTAB.18.091301
A. Yuen, S. Lund, J. Barnard, R. Cohen, J. Wurtele
A stack of thin, closely spaced conducting foils has been investigated by Lund et al. [Phys. Rev. ST Accel. Beams 16, 044202 (2013)] as a passive focusing lens for intense ion beams. The foils mitigate space-charge defocusing forces to enable the beam self-magnetic field to focus. In this study, we analyze possible degradation of focusing due to scattering of beam ions resulting from finite foil thickness using an envelope model and numerical simulations with the particle-in-cell code WARP. Ranges of kinetic energy where scattering effects are sufficient to destroy passive focusing are quantified. The scheme may be utilized to focus protons produced in intense laser-solid accelerator schemes. As an example, the spot size of an initially collimated 30 MeV proton beam with initial rms radius $200text{ }text{ }ensuremath{mu}mathrm{m}$, perveance $Q=1.8ifmmodetimeselsetexttimesfi{}{10}^{ensuremath{-}2}$, and initial transverse emittance ${ϵ}_{x,mathrm{rms}}=0.87text{ }text{ }mathrm{mm}text{ }mathrm{mrad}$ propagating through a stack of $6.4text{ }text{ }ensuremath{mu}mathrm{m}$ thick foils, spaced $100text{ }text{ }ensuremath{mu}mathrm{m}$ apart, gives a $127.5text{ }text{ }ensuremath{mu}mathrm{m}$ spot with scattering and a $81.0text{ }text{ }ensuremath{mu}mathrm{m}$ spot without scattering, illustrating the importance of including scattering effects.
{"title":"Scattering effects in passive foil focusing of ion beams","authors":"A. Yuen, S. Lund, J. Barnard, R. Cohen, J. Wurtele","doi":"10.1103/PHYSREVSTAB.18.091301","DOIUrl":"https://doi.org/10.1103/PHYSREVSTAB.18.091301","url":null,"abstract":"A stack of thin, closely spaced conducting foils has been investigated by Lund et al. [Phys. Rev. ST Accel. Beams 16, 044202 (2013)] as a passive focusing lens for intense ion beams. The foils mitigate space-charge defocusing forces to enable the beam self-magnetic field to focus. In this study, we analyze possible degradation of focusing due to scattering of beam ions resulting from finite foil thickness using an envelope model and numerical simulations with the particle-in-cell code WARP. Ranges of kinetic energy where scattering effects are sufficient to destroy passive focusing are quantified. The scheme may be utilized to focus protons produced in intense laser-solid accelerator schemes. As an example, the spot size of an initially collimated 30 MeV proton beam with initial rms radius $200text{ }text{ }ensuremath{mu}mathrm{m}$, perveance $Q=1.8ifmmodetimeselsetexttimesfi{}{10}^{ensuremath{-}2}$, and initial transverse emittance ${ϵ}_{x,mathrm{rms}}=0.87text{ }text{ }mathrm{mm}text{ }mathrm{mrad}$ propagating through a stack of $6.4text{ }text{ }ensuremath{mu}mathrm{m}$ thick foils, spaced $100text{ }text{ }ensuremath{mu}mathrm{m}$ apart, gives a $127.5text{ }text{ }ensuremath{mu}mathrm{m}$ spot with scattering and a $81.0text{ }text{ }ensuremath{mu}mathrm{m}$ spot without scattering, illustrating the importance of including scattering effects.","PeriodicalId":20072,"journal":{"name":"Physical Review Special Topics-accelerators and Beams","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78324308","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}
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