Present understanding of accelerator optics is based mainly on classical mechanics and electrodynamics. In recent years quantum theory of charged-particle beam optics has been under development. In this paper the newly developed formalism is outlined.
{"title":"Quantum aspects of accelerator optics","authors":"S. Khan","doi":"10.1109/PAC.1999.792948","DOIUrl":"https://doi.org/10.1109/PAC.1999.792948","url":null,"abstract":"Present understanding of accelerator optics is based mainly on classical mechanics and electrodynamics. In recent years quantum theory of charged-particle beam optics has been under development. In this paper the newly developed formalism is outlined.","PeriodicalId":20453,"journal":{"name":"Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)","volume":"41 1","pages":"2817-2819 vol.4"},"PeriodicalIF":0.0,"publicationDate":"1999-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85754490","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 FEL of average power 200 kW is being designed at the LBNL for satellite power beaming. It utilizes the radiation of /spl sim/100 MeV electrons with /spl sim/200 A peak current. In order to obtain the desired peak current, the 5 mm long electron bunches delivered by a linear accelerator are compressed to 1 mm. Furthermore, it is important for the FEL operations that the compressed bunches have a uniform longitudinal density distribution over the entire bunch length. After the FEL, the electron beam is returned to the linear accelerator for deceleration. Since the electron beam acquires approximately 6% energy spread during radiation in the FEL, bunch de-compressor is used between the FEL and the linac to expand the electron bunches back to its original length and to reduce the energy spread. In the paper we present the design and analysis of the bunch compressor and the bunch de-compressor that perform the needed functions.
{"title":"Bunch compressor and de-compressor in the FEL for satellite power beaming","authors":"W. Wan, A. Zholents","doi":"10.1109/PAC.1999.792728","DOIUrl":"https://doi.org/10.1109/PAC.1999.792728","url":null,"abstract":"A FEL of average power 200 kW is being designed at the LBNL for satellite power beaming. It utilizes the radiation of /spl sim/100 MeV electrons with /spl sim/200 A peak current. In order to obtain the desired peak current, the 5 mm long electron bunches delivered by a linear accelerator are compressed to 1 mm. Furthermore, it is important for the FEL operations that the compressed bunches have a uniform longitudinal density distribution over the entire bunch length. After the FEL, the electron beam is returned to the linear accelerator for deceleration. Since the electron beam acquires approximately 6% energy spread during radiation in the FEL, bunch de-compressor is used between the FEL and the linac to expand the electron bunches back to its original length and to reduce the energy spread. In the paper we present the design and analysis of the bunch compressor and the bunch de-compressor that perform the needed functions.","PeriodicalId":20453,"journal":{"name":"Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)","volume":"48 1","pages":"2465-2467 vol.4"},"PeriodicalIF":0.0,"publicationDate":"1999-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79547611","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. Fox, R. Larsen, S. Prabhakar, D. Teytelman, A. Young, A. Drago, M. Serio, W. Barry, G. Stover
Longitudinal feedback systems based on a common programmable DSP architecture have been commissioned at 4 laboratories. In addition to longitudinal feedback and beam diagnostics these flexible systems have been programmed to provide diagnostics for transverse motion. The diagnostic functions are based on transient domain techniques which record the response of every bunch while the feedback system manipulates the beam. Operational experience from 4 installations is illustrated via experimental results from PEP-II, DA/spl Phi/NE, ALS and SPEAR. Modal growth and damping rates for transverse and longitudinal planes are measured via short (20 ms) transient excitations for unstable and stable coupled-bunch modes. Data from steady-state measurements are used to identify unstable modes, noise-driven beam motion, and noise sources. Techniques are illustrated which allow the prediction of instability thresholds from low-current measurements of stable beams. Transverse bunch train grow-damp sequences which measure the time evolution of instabilities along the bunch train are presented and compared to signatures expected from ion and fast ion instabilities.
{"title":"Multi-bunch instability diagnostics via digital feedback systems at PEP-II, DA/spl Phi/NE, ALS and SPEAR","authors":"J. Fox, R. Larsen, S. Prabhakar, D. Teytelman, A. Young, A. Drago, M. Serio, W. Barry, G. Stover","doi":"10.1109/PAC.1999.795781","DOIUrl":"https://doi.org/10.1109/PAC.1999.795781","url":null,"abstract":"Longitudinal feedback systems based on a common programmable DSP architecture have been commissioned at 4 laboratories. In addition to longitudinal feedback and beam diagnostics these flexible systems have been programmed to provide diagnostics for transverse motion. The diagnostic functions are based on transient domain techniques which record the response of every bunch while the feedback system manipulates the beam. Operational experience from 4 installations is illustrated via experimental results from PEP-II, DA/spl Phi/NE, ALS and SPEAR. Modal growth and damping rates for transverse and longitudinal planes are measured via short (20 ms) transient excitations for unstable and stable coupled-bunch modes. Data from steady-state measurements are used to identify unstable modes, noise-driven beam motion, and noise sources. Techniques are illustrated which allow the prediction of instability thresholds from low-current measurements of stable beams. Transverse bunch train grow-damp sequences which measure the time evolution of instabilities along the bunch train are presented and compared to signatures expected from ion and fast ion instabilities.","PeriodicalId":20453,"journal":{"name":"Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)","volume":"8 1","pages":"636-640 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1999-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88913596","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}
Control and Operational models for Vacuum Equipment have been studied at CERN for several years. A prototype implementation was tried out on ion gauges in LEP followed by a full-scale implementation for all vacuum equipment to be controlled in the newly built AD ring. In order to meet the tight time schedule, the existing hardware and software infrastructure of the PS complex has been used. The model server was built on top of this infrastructure. This has introduced some restrictions with respect to a full implementation of the models, but made the server available for all vacuum equipment already installed in the various accelerators which are connected to this control system. In order to test the server, a simplified man-machine interface has been created. This interface presents the available acquisition and control values in a very homogeneous way to the operator, making the advantage of the chosen model approach evident. It also makes additional diagnostic information, previously unavailable, accessible to the vacuum operators.
{"title":"First experience with control and operational models for vacuum equipment in the AD decelerator","authors":"P.M. Strubin, N. Trofimov","doi":"10.1109/PAC.1999.795701","DOIUrl":"https://doi.org/10.1109/PAC.1999.795701","url":null,"abstract":"Control and Operational models for Vacuum Equipment have been studied at CERN for several years. A prototype implementation was tried out on ion gauges in LEP followed by a full-scale implementation for all vacuum equipment to be controlled in the newly built AD ring. In order to meet the tight time schedule, the existing hardware and software infrastructure of the PS complex has been used. The model server was built on top of this infrastructure. This has introduced some restrictions with respect to a full implementation of the models, but made the server available for all vacuum equipment already installed in the various accelerators which are connected to this control system. In order to test the server, a simplified man-machine interface has been created. This interface presents the available acquisition and control values in a very homogeneous way to the operator, making the advantage of the chosen model approach evident. It also makes additional diagnostic information, previously unavailable, accessible to the vacuum operators.","PeriodicalId":20453,"journal":{"name":"Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)","volume":"27 2 1","pages":"346-348 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1999-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83014708","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}
CERN has built a new experimental facility, called the Antiproton Decelerator (AD), by transforming two existing machines: the "Antiproton Collector" (AC) and the "Antiproton Accumulator" (AA). To achieve adequate beam performance once the antiproton beam is decelerated to its final value of 0.1 GeV/c, it was necessary to lower the average pressure by nearly two orders of magnitude. For this purpose, a large number of additional pumps were installed and a very careful preparation was applied to a variety of special machine equipment which, in its original construction, was not designed for ultra-high vacuum operation. An important improvement in the outgassing rates was achieved through an extended, mild bake-out of tanks and vacuum vessels containing large amounts of ferrite material and multi-layer thermal insulation. This paper describes the necessary modifications of the vacuum system and in more detail the various steps taken to obtain the required pressure in the low 10/sup -10/ mbar range. It will also report on the unexpected difficulties which were encountered by re-using vacuum components that were not initially designed for bake-out.
{"title":"The AD vacuum system: construction and commissioning","authors":"M. Brouet, J. Hansen, H. Klette, P. Strubin","doi":"10.1109/PAC.1999.795760","DOIUrl":"https://doi.org/10.1109/PAC.1999.795760","url":null,"abstract":"CERN has built a new experimental facility, called the Antiproton Decelerator (AD), by transforming two existing machines: the \"Antiproton Collector\" (AC) and the \"Antiproton Accumulator\" (AA). To achieve adequate beam performance once the antiproton beam is decelerated to its final value of 0.1 GeV/c, it was necessary to lower the average pressure by nearly two orders of magnitude. For this purpose, a large number of additional pumps were installed and a very careful preparation was applied to a variety of special machine equipment which, in its original construction, was not designed for ultra-high vacuum operation. An important improvement in the outgassing rates was achieved through an extended, mild bake-out of tanks and vacuum vessels containing large amounts of ferrite material and multi-layer thermal insulation. This paper describes the necessary modifications of the vacuum system and in more detail the various steps taken to obtain the required pressure in the low 10/sup -10/ mbar range. It will also report on the unexpected difficulties which were encountered by re-using vacuum components that were not initially designed for bake-out.","PeriodicalId":20453,"journal":{"name":"Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)","volume":"66 5 1","pages":"562-564 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1999-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87252897","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}
The dynamic aperture for version 5.1, with a 300 /spl mu/r crossing angle at IP1 and IP5, of the Large Hadron Collider (LHC) lattice has been estimated using the tracking code TEVLAT. The dynamic aperture calculated here is due to the magnetic field errors in the high gradient quadrupoles (MQX) in the two low-/spl beta/ interaction regions at IR1 and IR5. No errors were assigned to the magnets in the arc regions of the lattice, nor were beam-beam effects incorporated. The dynamic aperture is expressed in terms of the /spl sigma/ of the beam corresponding to the beam emittance of 3.75 mm mr. With only short term tracking, the combined effect of the multipoles and the crossing angle is to yield an average (over multipole coefficients generated with 100 different seeds) dynamic aperture of /spl ap/11.7/spl plusmn/1.2.
使用跟踪代码TEVLAT对大型强子对撞机(LHC)晶格在IP1和IP5处具有300 /spl mu/r交叉角的5.1版本的动态孔径进行了估计。本文计算的动态孔径是由于高梯度四极(MQX)在IR1和IR5两个低/spl β /相互作用区域的磁场误差造成的。没有错误被分配到磁体在圆弧区域的晶格，也没有光束效应纳入。动态孔径以光束发射度为3.75 mm mr时光束的/spl sigma/表示。在仅进行短期跟踪的情况下，多极子和交叉角的综合效应产生的平均动态孔径为/spl ap/11.7/spl plusmn/1.2。
{"title":"A calculation of the dynamic aperture of the LHC at collision","authors":"N. Gelfand","doi":"10.1109/PAC.1999.792963","DOIUrl":"https://doi.org/10.1109/PAC.1999.792963","url":null,"abstract":"The dynamic aperture for version 5.1, with a 300 /spl mu/r crossing angle at IP1 and IP5, of the Large Hadron Collider (LHC) lattice has been estimated using the tracking code TEVLAT. The dynamic aperture calculated here is due to the magnetic field errors in the high gradient quadrupoles (MQX) in the two low-/spl beta/ interaction regions at IR1 and IR5. No errors were assigned to the magnets in the arc regions of the lattice, nor were beam-beam effects incorporated. The dynamic aperture is expressed in terms of the /spl sigma/ of the beam corresponding to the beam emittance of 3.75 mm mr. With only short term tracking, the combined effect of the multipoles and the crossing angle is to yield an average (over multipole coefficients generated with 100 different seeds) dynamic aperture of /spl ap/11.7/spl plusmn/1.2.","PeriodicalId":20453,"journal":{"name":"Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)","volume":"132 1","pages":"2861-2863 vol.4"},"PeriodicalIF":0.0,"publicationDate":"1999-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74553475","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}
In order to achieve the design luminosity of the Next Linear Collider, the main linac must accelerate trains of bunches from 10 GeV to 500 GeV while preserving vertical normalized emittances on the order of 0.05 mm.mrad. We describe a set of simulation studies, performed using the program LIAR, comparing several algorithms for steering the main linac; the algorithms are compared on the basis of emittance preservation, convergence speed, and sensitivity to BNS phase profile. The effects of an ATL mechanism during the steering procedure are also studied.
{"title":"Simulation studies of main linac steering in the Next Linear Collider","authors":"P. Tenenbaum","doi":"10.1109/PAC.1999.792336","DOIUrl":"https://doi.org/10.1109/PAC.1999.792336","url":null,"abstract":"In order to achieve the design luminosity of the Next Linear Collider, the main linac must accelerate trains of bunches from 10 GeV to 500 GeV while preserving vertical normalized emittances on the order of 0.05 mm.mrad. We describe a set of simulation studies, performed using the program LIAR, comparing several algorithms for steering the main linac; the algorithms are compared on the basis of emittance preservation, convergence speed, and sensitivity to BNS phase profile. The effects of an ATL mechanism during the steering procedure are also studied.","PeriodicalId":20453,"journal":{"name":"Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)","volume":"1 1","pages":"3459-3461 vol.5"},"PeriodicalIF":0.0,"publicationDate":"1999-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88120959","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}
Prototypes of 13 kA HTS current leads for the Large Hadron Collider (LHC) have been specified by CERN and produced by several manufacturers. The specification defines the required thermo-electric performance and the geometric limitations imposed by the LHC infrastructure. A report is given of the results obtained from extensive tests on these leads.
用于大型强子对撞机(LHC)的13 kA HTS电流引线的原型已经由欧洲核子研究中心指定，并由几家制造商生产。该规范定义了所需的热电性能和LHC基础设施施加的几何限制。报告了对这些引线进行广泛试验所获得的结果。
{"title":"Test results on the first 13 kA prototype HTS leads for the LHC","authors":"A. Ballarino, L. Serio","doi":"10.1109/PAC.1999.795563","DOIUrl":"https://doi.org/10.1109/PAC.1999.795563","url":null,"abstract":"Prototypes of 13 kA HTS current leads for the Large Hadron Collider (LHC) have been specified by CERN and produced by several manufacturers. The specification defines the required thermo-electric performance and the geometric limitations imposed by the LHC infrastructure. A report is given of the results obtained from extensive tests on these leads.","PeriodicalId":20453,"journal":{"name":"Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)","volume":"13 1","pages":"1405-1407 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1999-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77695025","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}
P. Tenenbaum, L. Eriksson, T. Markiewicz, T. Raubenheimer, A. Ringwall
We review many developments in the design of the beam delivery system for the Next Linear Collider. The collimation system has been redesigned to reduce nonlinearities and ease tolerances, and the IP switch line has been adjusted to permit a 300 meter longitudinal separation between the two detectors. Magnet designs have been changed to reduce the number of distinct magnet classes, produce a smoother vacuum chamber, and improve pumping. A revised set of interaction-region quadrupoles achieves the optical requirements of the system with improved beam stay-clears, and performance of the final focus at various energies has been simulated and found acceptable. Studies have begun on the set of feedbacks required to maintain the stability of the system and the changes in tolerances thus implied.
{"title":"New developments in the Next Linear Collider beam delivery system design","authors":"P. Tenenbaum, L. Eriksson, T. Markiewicz, T. Raubenheimer, A. Ringwall","doi":"10.1109/PAC.1999.792337","DOIUrl":"https://doi.org/10.1109/PAC.1999.792337","url":null,"abstract":"We review many developments in the design of the beam delivery system for the Next Linear Collider. The collimation system has been redesigned to reduce nonlinearities and ease tolerances, and the IP switch line has been adjusted to permit a 300 meter longitudinal separation between the two detectors. Magnet designs have been changed to reduce the number of distinct magnet classes, produce a smoother vacuum chamber, and improve pumping. A revised set of interaction-region quadrupoles achieves the optical requirements of the system with improved beam stay-clears, and performance of the final focus at various energies has been simulated and found acceptable. Studies have begun on the set of feedbacks required to maintain the stability of the system and the changes in tolerances thus implied.","PeriodicalId":20453,"journal":{"name":"Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)","volume":"12 1","pages":"3462-3464 vol.5"},"PeriodicalIF":0.0,"publicationDate":"1999-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86789032","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}
Using an automated magnet measurement system employing a variety of current excitation ramps, extensive studies of the hysteretic behavior of magnet strength have been carried out. An analytic description which is accurate at better than 0.1% has been achieved. Prescriptions for setting field strength using these formulas will be adequate for multi-energy operation of the Fermilab Main Injector, for deceleration in the Main Injector and Accumulator and for multi-energy operation of various beamline magnets. An overview of this work is provided. Important regularities of the magnet behavior are identified.
{"title":"Hysteresis study techniques and results for accelerator magnets with unipolar current excitation","authors":"B. Brown","doi":"10.1109/PAC.1999.792288","DOIUrl":"https://doi.org/10.1109/PAC.1999.792288","url":null,"abstract":"Using an automated magnet measurement system employing a variety of current excitation ramps, extensive studies of the hysteretic behavior of magnet strength have been carried out. An analytic description which is accurate at better than 0.1% has been achieved. Prescriptions for setting field strength using these formulas will be adequate for multi-energy operation of the Fermilab Main Injector, for deceleration in the Main Injector and Accumulator and for multi-energy operation of various beamline magnets. An overview of this work is provided. Important regularities of the magnet behavior are identified.","PeriodicalId":20453,"journal":{"name":"Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)","volume":"8 1","pages":"3315-3317 vol.5"},"PeriodicalIF":0.0,"publicationDate":"1999-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79471668","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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