{"title":"Space Charge Effects for Transverse Collective Instabilities in Circular Machines","authors":"A. Burov","doi":"10.23732/CYRCP-2020-009.9","DOIUrl":"https://doi.org/10.23732/CYRCP-2020-009.9","url":null,"abstract":"A brief historical review is presented of progressing understanding of transverse coherent instabilities of charged particles beams in circular machines when both Coulomb and wake fields are important. The paper relates to a talk given at ICFA Workshop on Mitigation of Coherent Beam Instabilities in Particle Accelerators, 23-27 September 2019 in Zermatt, Switzerland.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73402012","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}
L. Rovige, J. Huijts, A. Vernier, V. Tomkus, V. Girdauskas, G. Račiukaitis, J. Dudutis, V. Stankevič, P. Gečys, Marie Ouillé, Z. Cheng, R. López-Martens, J. Faure
{"title":"Demonstration of stable long-term operation of a kilohertz laser-plasma accelerator","authors":"L. Rovige, J. Huijts, A. Vernier, V. Tomkus, V. Girdauskas, G. Račiukaitis, J. Dudutis, V. Stankevič, P. Gečys, Marie Ouillé, Z. Cheng, R. López-Martens, J. Faure","doi":"10.1103/PHYSREVACCELBEAMS.23.093401","DOIUrl":"https://doi.org/10.1103/PHYSREVACCELBEAMS.23.093401","url":null,"abstract":"We report on the stable and continuous operation of a kilohertz laser-plasma accelerator. Electron bunches with 2.6 pC charge and 2.5 MeV peak energy were generated via injection and trapping in a downward plasma density ramp. This density transition was produced in a newly designed asymmetrically shocked gas nozzle. The reproducibility of the electron source was also assessed over a period of a week and found to be satisfactory with similar values of the beam charge and energy. These results show that the reproducibility and stability of the laser-plasma accelerator are greatly enhanced on the long-term scale when using a robust scheme for density gradient injection.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87551035","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}
F. Asvesta, H. Bartosik, S. Gilardoni, A. Huschauer, S. Machida, Y. Papaphilippou, R. Wasef
{"title":"Identification and characterization of high order incoherent space charge driven structure resonances in the CERN Proton Synchrotron","authors":"F. Asvesta, H. Bartosik, S. Gilardoni, A. Huschauer, S. Machida, Y. Papaphilippou, R. Wasef","doi":"10.1103/PHYSREVACCELBEAMS.23.091001","DOIUrl":"https://doi.org/10.1103/PHYSREVACCELBEAMS.23.091001","url":null,"abstract":"Space charge is typically one of the performance limitations for the operation of high intensity and high brightness beams in circular accelerators. In the Proton Synchrotron (PS) at CERN, losses are observed for vertical tunes above $Q_y=6.25$, especially for beams with large space charge tune shift. The work presented here shows that this behaviour is associated to structure resonances excited by space charge due to the highly symmetric accelerator lattice of the PS, typical for first generation alternating gradient synchrotrons. Experimental studies demonstrate the dependency of the losses on the beam brightness and the harmonic of the resonance, and simulation studies reveal the incoherent nature of the resonance. Furthermore, the calculation of the Resonance Driving Terms (RDT) generated by the space charge potential shows that the operational working point of the PS is surrounded by multiple space charge driven incoherent resonances. Finally, measurements and simulations on both lattice driven and space charge driven resonances illustrate the different behaviour of the beam loss depending on the source of the resonance excitation and on the beam brightness.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90141565","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}
M. Turner, P. Muggli, E. Adli, R. Agnello, M. Aladi, Y. Andrèbe, O. Apsimon, R. Apsimon, A. Bachmann, M. Baistrukov, F. Batsch, M. Bergamaschi, P. Blanchard, P. Burrows, B. Buttenschön, A. Caldwell, J. Chappell, E. Chevallay, M. Chung, D. Cooke, H. Damerau, C. Davut, G. Demeter, L. Deubner, A. Dexter, G. Djotyan, S. Doebert, J. Farmer, A. Fasoli, V. Fedosseev, R. Fiorito, R. Fonseca, F. Friebel, I. Furno, L. Garolfi, S. Gessner, B. Goddard, I. Gorgisyan, A. Gorn, Eduardo Granados, M. Granetzny, O. Grulke, E. Gschwendtner, V. Hafych, A. Hartin, A. Helm, J. Henderson, A. Howling, M. Hüther, R. Jacquier, S. Jolly, I. Kargapolov, M. Kedves, F. Keeble, M. D. Kelisani, S. Kim, F. Kraus, M. Krupa, T. Lefevre, Y. Li, L. Liang, S. Liu, N. Lopes, K. Lotov, M. Martyanov, S. Mazzoni, D. Medina Godoy, V. A. Minakov, J. Moody, P. Morales Guzmán, M. Moreira, H. Panuganti, A. Pardons, F. Peña Asmus, A. Perera, A. Petrenko, J. Půček, A. Pukhov, B. Ráczkevi, R. Ramjiawan, S. Rey, H. Ruhl, H. Saberi, O. Schmitz, E. Senes, P
{"title":"Experimental study of wakefields driven by a self-modulating proton bunch in plasma","authors":"M. Turner, P. Muggli, E. Adli, R. Agnello, M. Aladi, Y. Andrèbe, O. Apsimon, R. Apsimon, A. Bachmann, M. Baistrukov, F. Batsch, M. Bergamaschi, P. Blanchard, P. Burrows, B. Buttenschön, A. Caldwell, J. Chappell, E. Chevallay, M. Chung, D. Cooke, H. Damerau, C. Davut, G. Demeter, L. Deubner, A. Dexter, G. Djotyan, S. Doebert, J. Farmer, A. Fasoli, V. Fedosseev, R. Fiorito, R. Fonseca, F. Friebel, I. Furno, L. Garolfi, S. Gessner, B. Goddard, I. Gorgisyan, A. Gorn, Eduardo Granados, M. Granetzny, O. Grulke, E. Gschwendtner, V. Hafych, A. Hartin, A. Helm, J. Henderson, A. Howling, M. Hüther, R. Jacquier, S. Jolly, I. Kargapolov, M. Kedves, F. Keeble, M. D. Kelisani, S. Kim, F. Kraus, M. Krupa, T. Lefevre, Y. Li, L. Liang, S. Liu, N. Lopes, K. Lotov, M. Martyanov, S. Mazzoni, D. Medina Godoy, V. A. Minakov, J. Moody, P. Morales Guzmán, M. Moreira, H. Panuganti, A. Pardons, F. Peña Asmus, A. Perera, A. Petrenko, J. Půček, A. Pukhov, B. Ráczkevi, R. Ramjiawan, S. Rey, H. Ruhl, H. Saberi, O. Schmitz, E. Senes, P","doi":"10.1103/PHYSREVACCELBEAMS.23.081302","DOIUrl":"https://doi.org/10.1103/PHYSREVACCELBEAMS.23.081302","url":null,"abstract":"We study experimentally the longitudinal and transverse wakefields driven by a highly relativistic proton bunch during self-modulation in plasma. We show that the wakefields' growth and amplitude increase with increasing seed amplitude as well as with the proton bunch charge in the plasma. We study transverse wakefields using the maximum radius of the proton bunch distribution measured on a screen downstream from the plasma. We study longitudinal wakefields by externally injecting electrons and measuring their final energy. Measurements agree with trends predicted by theory and numerical simulations and validate our understanding of the development of self-modulation. Experiments were performed in the context of the Advanced Wakefield Experiment (AWAKE).","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81096800","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}
A. Tyukhtin, S. Galyamin, V. Vorobev, A. A. Grigoreva
{"title":"Cherenkov radiation of a charge flying through the inverted conical target","authors":"A. Tyukhtin, S. Galyamin, V. Vorobev, A. A. Grigoreva","doi":"10.1103/physreva.102.053514","DOIUrl":"https://doi.org/10.1103/physreva.102.053514","url":null,"abstract":"Radiation generated by a charge moving through a vacuum channel in a dielectric cone is analyzed. It is assumed that the charge moves through the cone from the apex side to the base side (the case of \"inverted\" cone). The cone size is supposed to be much larger than the wavelengths under consideration. We calculate the wave field outside the target using the \"aperture method\" developed in our previous papers. Contrary to the problems considered earlier, here the wave which incidences directly on the aperture is not the main wave, while the wave once reflected from the lateral surface is much more important. The general formulas for the radiation field are obtained, and the particular cases of the ray optics area and the Fraunhofer area are analyzed. Significant physical effects including the phenomenon of \"Cherenkov spotlight\" are discussed. In particular it is shown that this phenomenon allows reaching essential enhancement of the radiation intensity in the far-field region at certain selection of the problem parameters. Owing to the \"inverted\" cone geometry, this effect can be realized for arbitrary charge velocity, including the ultra relativistic case, by proper selection of the cone material and the apex angle. Typical radiation patterns in the far-field area are demonstrated.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86908473","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}
{"title":"Mitigation of Collective Effects by Optics Optimisation","authors":"Y. Papaphilippou, F. Antoniou, H. Bartosik","doi":"10.23732/CYRCP-2020-009.74","DOIUrl":"https://doi.org/10.23732/CYRCP-2020-009.74","url":null,"abstract":"This paper covers recent progress in the design of optics solutions to minimize collective effects such as beam instabilities, intra-beam scattering or space charge in hadron and lepton rings. The necessary steps are reviewed for designing the optics of high-intensity and high-brightness synchrotrons but also ultra-low emittance lepton storage rings, whose performance is strongly dominated by collective effects. Particular emphasis is given to proposed and existing designs illustrated by simulations and beam measurements.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88049454","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}
{"title":"Suppression of the longitudinal coupled bunch instability in DA${Phi}$NE in collisions with a crossing angle","authors":"A. Drago, M. Zobov, D. Shatilov, P. Raimondi","doi":"10.23732/CYRCP-2020-009.101","DOIUrl":"https://doi.org/10.23732/CYRCP-2020-009.101","url":null,"abstract":"In DAFNE, the Frascati $e^+e^-$ collider operating since 1998, an innovative collision scheme, the crab waist, has been successfully implemented during the years 2008-09. During operations for the Siddharta experiment an unusual synchrotron oscillation damping effect induced by beam-beam collisions has been observed. Indeed, when the longitudinal feedback is off, the positron beam becomes unstable with currents above 200-300 mA due to coupled bunch instability. The longitudinal instability is damped by colliding the positron beam with a high current electron beam (of the order of 2 A). A shift of about -600 Hz in the residual synchrotron sidebands is observed. Precise measurements have been performed by using both a commercial spectrum analyzer and the diagnostic capabilities of the longitudinal bunch-by-bunch feedback. The damping effect has been observed in DAFNE for the first time during collisions with the crab waist scheme. Our explanation, based both on theoretical consideration and modeling simulation, is that beam collisions with a large crossing angle produce longitudinal tune shift and spread, providing Landau damping of synchrotron oscillations.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74215017","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}
A. Drago, INFN-LNF, Frascati, T. University, Romé, Italy D. Alesini, S. Caschera, A. Gallo, Italy J.D. Fox, S. University, Stanford, Usa J. Cesaratto, J. Dusatko, J. Olsen, C. Rivetta, O. Turgut, Slac, Menlo Park, U. Hofle, G. Iadarola, K. Li, E. Métral, E. Montesinos, G. Rumolo, Cern, Geneva, S. D. Santis, M. Furman, J. Vay, Lbnl, Berkeley, Usa M. Tobiyama, Kek, Tsukuba, Japan.
{"title":"Intra-bunch feedback system developments at DAFNE","authors":"A. Drago, INFN-LNF, Frascati, T. University, Romé, Italy D. Alesini, S. Caschera, A. Gallo, Italy J.D. Fox, S. University, Stanford, Usa J. Cesaratto, J. Dusatko, J. Olsen, C. Rivetta, O. Turgut, Slac, Menlo Park, U. Hofle, G. Iadarola, K. Li, E. Métral, E. Montesinos, G. Rumolo, Cern, Geneva, S. D. Santis, M. Furman, J. Vay, Lbnl, Berkeley, Usa M. Tobiyama, Kek, Tsukuba, Japan.","doi":"10.23732/CYRCP-2020-007.223","DOIUrl":"https://doi.org/10.23732/CYRCP-2020-007.223","url":null,"abstract":"This paper presents history and evolution of the intra-bunch feedback system for circular accelerators. This pro-ject has been presented by John D. Fox (SLAC/Stanford Un.) at the IPAC2010 held in Kyoto. The idea of the pro-posal is to build a flexible and powerful instrument to mit-igate the parasitic e-cloud effects on the proton (and poten-tially positron) beams in storage rings. Being a new and ambitious project, the financial issues have been quite im-portant. US LHC Accelerator Research Program (LARP) and other institution funding sources have assured the de-velopment of the design for implementing the feedback in the SPS ring at CERN. Here the intra-bunch feedback sys-tem has been installed and tested in the frame of the LIU (LHC Injector Upgrade) program. After the end of the LARP funding, a possible new inter-esting chance to continue the R&D activity, could be by implementing the system in a lepton storage ring affected by e-cloud effects. For achieving this goal, a possible ex-periment could be carried out in the positron ring of DAFNE at Frascati, Italy. The feasibility of the proposal is evaluated in the following sections. In case of approval of the experiment, indeed the project could be inserted in the DAFNE-TF (DAFNE Test Facility) program that is fore-seen after the 2020 for the following 3-5 years.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83769879","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}
{"title":"Damping rate limitations for transverse dampers in large hadron colliders","authors":"V. Lebedev, B. Fermilab","doi":"10.23732/CYRCP-2020-009.203","DOIUrl":"https://doi.org/10.23732/CYRCP-2020-009.203","url":null,"abstract":"The paper focuses on two issues important for design and operation of bunch-by-bunch transverse damper in a very large hadron collider, where fast damping is required to suppress beam instabilities and noise induced emittance growth. The first issue is associated with kick variation along a bunch which affects the damping of head-tail modes. The second issue is associated with affect of damper noise on the instability threshold.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75321705","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}
J. Götzfried, J. Götzfried, A. Döpp, A. Döpp, M. Gilljohann, M. Gilljohann, F. Foerster, H. Ding, H. Ding, S. Schindler, S. Schindler, G. Schilling, A. Buck, L. Veisz, L. Veisz, S. Karsch, S. Karsch
{"title":"Physics of High-Charge Electron Beams in Laser-Plasma Wakefields","authors":"J. Götzfried, J. Götzfried, A. Döpp, A. Döpp, M. Gilljohann, M. Gilljohann, F. Foerster, H. Ding, H. Ding, S. Schindler, S. Schindler, G. Schilling, A. Buck, L. Veisz, L. Veisz, S. Karsch, S. Karsch","doi":"10.1103/PHYSREVX.10.041015","DOIUrl":"https://doi.org/10.1103/PHYSREVX.10.041015","url":null,"abstract":"Laser wakefield acceleration (LWFA) and its particle-driven counterpart, plasma wakefield acceleration (PWFA), are commonly treated as separate, though related branches of high-gradient plasma-based acceleration. However, novel proposed schemes are increasingly residing at the interface of both concepts where the understanding of their interplay becomes crucial. Here, we report on experiments covering a wide range of parameters by using nanocoulomb-class quasi-monoenergetic electron beams from LWFA with a 100-TW-class laser. Based on a controlled electron injection, these beams reach record-level performance in terms of laser-to-beam energy transfer efficiency (up to 10%), spectral charge density (regularly exceeding 10 pC/MeV) and divergence (1 mrad full width at half maximum divergence). The impact of charge fluctuations on the energy spectra of electron bunches is assessed for different laser parameters, including a few-cycle laser, followed by a presentation of results on beam loading in LWFA with two electron bunches. This scenario is particularly promising to provide high-quality electron beams by using one of the bunches to either tailor the laser wakefield via beam loading or to drive its own, beam-dominated wakefield. We present experimental evidence for the latter, showing a varying acceleration of a low-energy witness beam with respect to the charge of a high-energy drive beam in a spatially separate gas target. With the increasing availability of petawatt-class lasers the access to this new regime of laser-plasma wakefield acceleration will be further facilitated, thus providing new paths towards low-emittance beam generation for future plasma-based colliders or light sources.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90511104","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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