Pub Date : 2020-02-17DOI: 10.1016/j.nima.2020.164797
S. Karanth, E. Stephenson, A. Wrońska, G. Ciullo, S. Dymov, R. Gebel, G. Guidoboni, V. Hejny, A. Kacharava, I. Keshelashvili, P. Kulessa, P. Lenisa, A. Lehrach, B. Lorentz, D. Mchedlishvili, A. Nass, N. Nikolaev, A. Pesce, J. Pretz, D. Prasuhn, F. Rathmann, A. Saleev, Y. Senichev, V. Shmakova, H. Stroeher, R. Talman, Y. Valdau, C. Weidemann, P. University, Cracow, Poland, I. University, Bloomington, Indiana., Usa, U. Ferrara, Infn, Ferrara, Italy., Forschungszentrum Juelich, H Germany, J. I. O. N. Research, Dubna, Russia., Institute of Nuclear Physics Pan, A. University, Aachen, Tbilisi State University, Tbilisi, Georgia, L. I. F. T. Physics, Chernogolovka, M. Physics, Technology, Dolgoprudny, B. III.PhysikalischesInstitut, R. University, S. University, Samara, C. University, Ithaca, N. York, USA. Forschungszentrum Juelich
{"title":"Influence of electron cooling on the polarization lifetime of a horizontally polarized storage ring beam","authors":"S. Karanth, E. Stephenson, A. Wrońska, G. Ciullo, S. Dymov, R. Gebel, G. Guidoboni, V. Hejny, A. Kacharava, I. Keshelashvili, P. Kulessa, P. Lenisa, A. Lehrach, B. Lorentz, D. Mchedlishvili, A. Nass, N. Nikolaev, A. Pesce, J. Pretz, D. Prasuhn, F. Rathmann, A. Saleev, Y. Senichev, V. Shmakova, H. Stroeher, R. Talman, Y. Valdau, C. Weidemann, P. University, Cracow, Poland, I. University, Bloomington, Indiana., Usa, U. Ferrara, Infn, Ferrara, Italy., Forschungszentrum Juelich, H Germany, J. I. O. N. Research, Dubna, Russia., Institute of Nuclear Physics Pan, A. University, Aachen, Tbilisi State University, Tbilisi, Georgia, L. I. F. T. Physics, Chernogolovka, M. Physics, Technology, Dolgoprudny, B. III.PhysikalischesInstitut, R. University, S. University, Samara, C. University, Ithaca, N. York, USA. Forschungszentrum Juelich","doi":"10.1016/j.nima.2020.164797","DOIUrl":"https://doi.org/10.1016/j.nima.2020.164797","url":null,"abstract":"","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74013754","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}
Our objective will be to integrate ML into Fermilab accelerator operations and furthermore provide an accessible framework which can also be used by a broad range of other accelerator systems with dynamic tuning needs. We will develop of real-time accelerator control using embedded ML on-chip hardware and fast communication between distributed systems in this proposal. We will demonstrate this technology for the Mu2e experiment by increasing the overall duty factor and uptime of the experiment through two synergistic projects. First, we will use deep reinforcement learning techniques to improve the performance of the regulation loop through guided optimization to provide stable proton beams extracted from the Delivery Ring to the Mu2e experiment. This requires the development of a digital twin of the system to model the accelerator and develop real-time ML algorithms. Second, we will use de-blending techniques to disentangle and classify overlapping beam losses in the Main Injector and Recycler Ring to reduce overall beam downtime in each machine. This ML model will be deployed within a semi-autonomous operational mode. Both applications require processing at the millisecond scale and will share similar ML-in-hardware techniques and beam instrumentation readout technology. A collaboration between Fermilab and Northwestern University will pull together the talents and resources of accelerator physicists, beam instrumentation engineers, embedded system architects, FPGA board design experts, and ML experts to solve complex real-time accelerator controls challenges which will enhance the physics program. More broadly, the framework developed for Accelerator Real-time Edge AI Distributed Systems (READS) can be applied to future projects as the accelerator complex is upgraded for the PIP-II and DUNE era.
{"title":"Accelerator Real-time Edge AI for Distributed Systems (READS) Proposal","authors":"K. Seiya","doi":"10.2172/1769391","DOIUrl":"https://doi.org/10.2172/1769391","url":null,"abstract":"Our objective will be to integrate ML into Fermilab accelerator operations and furthermore provide an accessible framework which can also be used by a broad range of other accelerator systems with dynamic tuning needs. We will develop of real-time accelerator control using embedded ML on-chip hardware and fast communication between distributed systems in this proposal. We will demonstrate this technology for the Mu2e experiment by increasing the overall duty factor and uptime of the experiment through two synergistic projects. First, we will use deep reinforcement learning techniques to improve the performance of the regulation loop through guided optimization to provide stable proton beams extracted from the Delivery Ring to the Mu2e experiment. This requires the development of a digital twin of the system to model the accelerator and develop real-time ML algorithms. Second, we will use de-blending techniques to disentangle and classify overlapping beam losses in the Main Injector and Recycler Ring to reduce overall beam downtime in each machine. This ML model will be deployed within a semi-autonomous operational mode. Both applications require processing at the millisecond scale and will share similar ML-in-hardware techniques and beam instrumentation readout technology. A collaboration between Fermilab and Northwestern University will pull together the talents and resources of accelerator physicists, beam instrumentation engineers, embedded system architects, FPGA board design experts, and ML experts to solve complex real-time accelerator controls challenges which will enhance the physics program. More broadly, the framework developed for Accelerator Real-time Edge AI Distributed Systems (READS) can be applied to future projects as the accelerator complex is upgraded for the PIP-II and DUNE era.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77063869","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 : 2020-01-13DOI: 10.1103/PHYSREVACCELBEAMS.23.072002
S. Setiniyaz, R. Apsimon, P. Williams
Recirculating energy recovery linacs are a promising technology for delivering high power particle beams ($sim$GW) while only requiring low power ($sim$kW) RF sources. This is achieved by decelerating the used bunches and using the energy they deposit in the accelerating structures to accelerate new bunches. We present studies of the impact of the bunch packet filling pattern on the performance of the accelerating RF system. We perform RF beam loading simulations under various noise levels and beam loading phases with different injection schemes. We also present a mathematical description of the RF system during the beam loading, which can identify optimal beam filling patterns under different conditions. The results of these studies have major implications for design constraints for future energy recovery linacs, by providing a quantitative metric for different machine designs and topologies.
{"title":"Implications of beam filling patterns on the design of recirculating energy recovery linacs","authors":"S. Setiniyaz, R. Apsimon, P. Williams","doi":"10.1103/PHYSREVACCELBEAMS.23.072002","DOIUrl":"https://doi.org/10.1103/PHYSREVACCELBEAMS.23.072002","url":null,"abstract":"Recirculating energy recovery linacs are a promising technology for delivering high power particle beams ($sim$GW) while only requiring low power ($sim$kW) RF sources. This is achieved by decelerating the used bunches and using the energy they deposit in the accelerating structures to accelerate new bunches. We present studies of the impact of the bunch packet filling pattern on the performance of the accelerating RF system. We perform RF beam loading simulations under various noise levels and beam loading phases with different injection schemes. We also present a mathematical description of the RF system during the beam loading, which can identify optimal beam filling patterns under different conditions. The results of these studies have major implications for design constraints for future energy recovery linacs, by providing a quantitative metric for different machine designs and topologies.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78501173","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}
Since the first vacuum tube (X-ray tube) was invented by Wilhelm Röntgen in Germany, after more than one hundred years of development, the average power density of the vacuum tube microwave source has reached the order of 108 [MW][GHz]2. In the high-power microwave field, the vacuum devices are still the mainstream microwave sources for applications such as scientific instruments, communications, radars, magnetic confinement fusion heating, microwave weapons, etc. The principles of microwave generation by vacuum tube microwave sources include Cherenkov or Smith-Purcell radiation, transition radiation, and Bremsstrahlung. In this paper, the vacuum tube microwave sources based on Cherenkov radiation were reviewed. Among them, the multi-wave Cherenkov generators can produce 15 GW output power in X-band. Cherenkov radiation vacuum tubes that can achieve continuous-wave operation include Traveling Wave Tubes and Magnetrons, with output power up to 1MW. Cherenkov radiation vacuum tubes that can generate frequencies of the order of 100 GHz and above include Traveling Wave Tubes, Backward Wave Oscillators, Magnetrons, Surface Wave Oscillators, Orotrons, etc.
{"title":"Review of the high-power vacuum tube microwave sources based on Cherenkov radiation","authors":"Weiye Xu, Handong Xu","doi":"10.31219/osf.io/vdk43","DOIUrl":"https://doi.org/10.31219/osf.io/vdk43","url":null,"abstract":"Since the first vacuum tube (X-ray tube) was invented by Wilhelm Röntgen in Germany, after more than one hundred years of development, the average power density of the vacuum tube microwave source has reached the order of 108 [MW][GHz]2. In the high-power microwave field, the vacuum devices are still the mainstream microwave sources for applications such as scientific instruments, communications, radars, magnetic confinement fusion heating, microwave weapons, etc. The principles of microwave generation by vacuum tube microwave sources include Cherenkov or Smith-Purcell radiation, transition radiation, and Bremsstrahlung. In this paper, the vacuum tube microwave sources based on Cherenkov radiation were reviewed. Among them, the multi-wave Cherenkov generators can produce 15 GW output power in X-band. Cherenkov radiation vacuum tubes that can achieve continuous-wave operation include Traveling Wave Tubes and Magnetrons, with output power up to 1MW. Cherenkov radiation vacuum tubes that can generate frequencies of the order of 100 GHz and above include Traveling Wave Tubes, Backward Wave Oscillators, Magnetrons, Surface Wave Oscillators, Orotrons, etc.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89388953","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 : 2019-12-30DOI: 10.1142/S0217751X19420326
K. Heinemann, D. Appelo, D. Barber, O. Beznosov, J. Ellison
In this paper we describe our work on spin polarization in high-energy electron storage rings which we base on the Bloch equation for the polarization density and which aims towards the e-/e+ option of the proposed Future Circular Collider (FCC-ee) and the proposed Circular Electron Positron Collider (CEPC). The Bloch equation takes into account non spin-flip and spin-flip effects due to synchrotron radiation including the spin-diffusion effects and the Sokolov-Ternov effect with its Baier-Katkov generalization as well as the kinetic-polarization effect. This mathematical model is an alternative to the standard mathematical model based on the Derbenev-Kondratenko formulas. For our numerical and analytical studies of the Bloch equation we develop an approximation to the latter to obtain an effective Bloch equation. This is accomplished by finding a third mathematical model based on a system of stochastic differential equations underlying the Bloch equation and by approximating that system via the method of averaging from perturbative ODE theory. We also give an overview of our algorithm for numerically integrating the effective Bloch equation. This discretizes the phase space using spectral methods and discretizes time via the additive Runge-Kutta method which is a high-order semi-implicit method. We also discuss the relevance of the third mathematical model for spin tracking.
{"title":"The Bloch equation for spin dynamics in electron storage rings: Computational and theoretical aspects","authors":"K. Heinemann, D. Appelo, D. Barber, O. Beznosov, J. Ellison","doi":"10.1142/S0217751X19420326","DOIUrl":"https://doi.org/10.1142/S0217751X19420326","url":null,"abstract":"In this paper we describe our work on spin polarization in high-energy electron storage rings which we base on the Bloch equation for the polarization density and which aims towards the e-/e+ option of the proposed Future Circular Collider (FCC-ee) and the proposed Circular Electron Positron Collider (CEPC). The Bloch equation takes into account non spin-flip and spin-flip effects due to synchrotron radiation including the spin-diffusion effects and the Sokolov-Ternov effect with its Baier-Katkov generalization as well as the kinetic-polarization effect. This mathematical model is an alternative to the standard mathematical model based on the Derbenev-Kondratenko formulas. For our numerical and analytical studies of the Bloch equation we develop an approximation to the latter to obtain an effective Bloch equation. This is accomplished by finding a third mathematical model based on a system of stochastic differential equations underlying the Bloch equation and by approximating that system via the method of averaging from perturbative ODE theory. We also give an overview of our algorithm for numerically integrating the effective Bloch equation. This discretizes the phase space using spectral methods and discretizes time via the additive Runge-Kutta method which is a high-order semi-implicit method. We also discuss the relevance of the third mathematical model for spin tracking.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79398148","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}
Los Alamos is currently developing novel particle accelerator controls and diagnostics algorithms to enable higher quality beams with lower beam losses than is currently possible. The purpose of this workshop was to consider tuning and optimization challenges of a wide range of particle accelerators including linear proton accelerators such as the Los Alamos Neutron Science Center (LANSCE), rings such as the Advanced Photon Source (APS) synchrotron, free electron lasers (FEL) such as the Linac Coherent Light Source (LCLS) and LCLS-II, the European X-ray Free Electron Laser (EuXFEL), the Swiss FEL, and the planned MaRIE FEL, and plasma wake-field accelerators such as FACET, FACET-II, and AWAKE at CERN. One major challenge is an the ability to quickly create very high quality, extremely intense, custom current and energy profile beams while working with limited real time non-invasive diagnostics and utilizing time-varying uncertain initial beam distributions and accelerator components. Currently, a few individual accelerator labs have been developing and applying their own diagnostics tools and custom control and ML algorithms for automated machine tuning and optimization. The goal of this workshop was to bring together a group of accelerator physicists and accelerator related control and ML experts in order to define which controls and diagnostics would be most useful for existing and future accelerators and to create a plan for developing a new family of algorithms that can be shared and maintained by the community.
{"title":"Advanced Control Methods for Particle Accelerators (ACM4PA) 2019","authors":"A. Scheinker, C. Emma, A. Edelen, S. Gessner","doi":"10.2172/1579684","DOIUrl":"https://doi.org/10.2172/1579684","url":null,"abstract":"Los Alamos is currently developing novel particle accelerator controls and diagnostics algorithms to enable higher quality beams with lower beam losses than is currently possible. The purpose of this workshop was to consider tuning and optimization challenges of a wide range of particle accelerators including linear proton accelerators such as the Los Alamos Neutron Science Center (LANSCE), rings such as the Advanced Photon Source (APS) synchrotron, free electron lasers (FEL) such as the Linac Coherent Light Source (LCLS) and LCLS-II, the European X-ray Free Electron Laser (EuXFEL), the Swiss FEL, and the planned MaRIE FEL, and plasma wake-field accelerators such as FACET, FACET-II, and AWAKE at CERN. One major challenge is an the ability to quickly create very high quality, extremely intense, custom current and energy profile beams while working with limited real time non-invasive diagnostics and utilizing time-varying uncertain initial beam distributions and accelerator components. Currently, a few individual accelerator labs have been developing and applying their own diagnostics tools and custom control and ML algorithms for automated machine tuning and optimization. The goal of this workshop was to bring together a group of accelerator physicists and accelerator related control and ML experts in order to define which controls and diagnostics would be most useful for existing and future accelerators and to create a plan for developing a new family of algorithms that can be shared and maintained by the community.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78360082","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}
Yongjun Li, Y. Hao, K. Hwang, R. Rainer, A. He, Ao Liu
A fast method for dynamic aperture (DA) optimization of storage rings has been developed through the use of reversal integration. While chaotic dynamical systems have exact time-reversal symmetry, numerical forward integration differs from its reversal due to scaled cumulative round-off errors. The difference, intrinsically associated with the Lyapunov exponent, is a generic indicator of chaos because it represents the sensitivity of chaotic motion to an initial condition. A chaos indicator of the charged particle motion is then obtained by comparing the forward integrations of particle trajectories with corresponding reversals, a.k.a. "backward integrations." The indicator was confirmed to be observable through short-term particle tracking simulations. Therefore, adopting it as an objective function could speed up optimization. The DA of the National Synchrotron Light Source II storage ring, and another test diffraction-limited light source ring, were optimized using this method for the purpose of demonstration.
{"title":"Fast Dynamic Aperture Optimization with Reversal Integration","authors":"Yongjun Li, Y. Hao, K. Hwang, R. Rainer, A. He, Ao Liu","doi":"10.2172/1631019","DOIUrl":"https://doi.org/10.2172/1631019","url":null,"abstract":"A fast method for dynamic aperture (DA) optimization of storage rings has been developed through the use of reversal integration. While chaotic dynamical systems have exact time-reversal symmetry, numerical forward integration differs from its reversal due to scaled cumulative round-off errors. The difference, intrinsically associated with the Lyapunov exponent, is a generic indicator of chaos because it represents the sensitivity of chaotic motion to an initial condition. A chaos indicator of the charged particle motion is then obtained by comparing the forward integrations of particle trajectories with corresponding reversals, a.k.a. \"backward integrations.\" The indicator was confirmed to be observable through short-term particle tracking simulations. Therefore, adopting it as an objective function could speed up optimization. The DA of the National Synchrotron Light Source II storage ring, and another test diffraction-limited light source ring, were optimized using this method for the purpose of demonstration.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88997171","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 plasma cascade instability (PCI) is a proposed mechanism for microbunching in electron beams without dipole magnets. Existing theory is limited to wave propagation that is orthogonal to the advective compression direction. This work provides a theory allowing for wave propagation in arbitrary directions.
{"title":"3D Theory of the Plasma Cascade Instability","authors":"M. Blaskiewicz","doi":"10.2172/1572972","DOIUrl":"https://doi.org/10.2172/1572972","url":null,"abstract":"The plasma cascade instability (PCI) is a proposed mechanism for microbunching in electron beams without dipole magnets. Existing theory is limited to wave propagation that is orthogonal to the advective compression direction. This work provides a theory allowing for wave propagation in arbitrary directions.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81940871","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 : 2019-06-04DOI: 10.18429/JACOW-FEL2019-TUP050
L. Campbell, H. Freund, J. Henderson, B. McNeil, P. Traczykowski, P. Slot
Free-electron lasers (FELs) operate at wavelengths down to hard x-rays, and are either seeded or start from noise. There is increasing interest in x-ray FELs that rely on Self-Amplified Spontaneous Emission (SASE), and this involves increasing simulation activity in the design, optimization, and characterization of these x-ray FELs. Most of the simulation codes in use rely on the Slowly-Varying Envelope Approximation (SVEA) in which Maxwell's equations are averaged over the fast time scale resulting in relatively small computational requirements. While the SVEA codes are generally successful, the predictions of these codes sometimes differ in various aspects of the FEL interaction. In contrast, Particle-in-Cell (PiC) simulation codes do not average Maxwell's equations and are considered to be a more complete model of the underlying physics.Unfortunately, they require much longer run times than SVEA codes and have not been validated by comparison with experiment as often as the SVEA codes. In order to remedy this, and to resolve issues that arise due to different predictions between the SVEA codes, we present a comparison between one SVEA code (MINERVA) and a PiC simulation code (PUFFIN) with the experimental measurements obtained at the SPARC SASE FEL experiment at ENEA Frascati. The results show good agreement between the two codes and between the codes and the experiment. Since the formulations of the two codes share no common elements, this validates both formulations and demonstrates the capability to model the FEL interaction from the start of teh undulator through the undulator and into deep saturation.
{"title":"Comparison Between, and Validation Against an Experiment of, a Slowly-Varying Envelope Approximation Code and a Particle-in-Cell Simulation Code for Free-Electron Lasers.","authors":"L. Campbell, H. Freund, J. Henderson, B. McNeil, P. Traczykowski, P. Slot","doi":"10.18429/JACOW-FEL2019-TUP050","DOIUrl":"https://doi.org/10.18429/JACOW-FEL2019-TUP050","url":null,"abstract":"Free-electron lasers (FELs) operate at wavelengths down to hard x-rays, and are either seeded or start from noise. There is increasing interest in x-ray FELs that rely on Self-Amplified Spontaneous Emission (SASE), and this involves increasing simulation activity in the design, optimization, and characterization of these x-ray FELs. Most of the simulation codes in use rely on the Slowly-Varying Envelope Approximation (SVEA) in which Maxwell's equations are averaged over the fast time scale resulting in relatively small computational requirements. While the SVEA codes are generally successful, the predictions of these codes sometimes differ in various aspects of the FEL interaction. In contrast, Particle-in-Cell (PiC) simulation codes do not average Maxwell's equations and are considered to be a more complete model of the underlying physics.Unfortunately, they require much longer run times than SVEA codes and have not been validated by comparison with experiment as often as the SVEA codes. In order to remedy this, and to resolve issues that arise due to different predictions between the SVEA codes, we present a comparison between one SVEA code (MINERVA) and a PiC simulation code (PUFFIN) with the experimental measurements obtained at the SPARC SASE FEL experiment at ENEA Frascati. The results show good agreement between the two codes and between the codes and the experiment. Since the formulations of the two codes share no common elements, this validates both formulations and demonstrates the capability to model the FEL interaction from the start of teh undulator through the undulator and into deep saturation.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90194523","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 : 2019-05-29DOI: 10.18429/JACoW-IPAC2019-WEXXPLS2
C. Ader, Mar Alvarez, J. Batko, R. Campos, M. McGee, A. Watts
Vacuum window research continues at Fermilab and this paper will examine cost effective, consistent designs which can have a huge impact on accelerator laboratories in terms of safety and cost. Issues such as the design, materials, analysis, testing and fabrication are addressed, including beam scattering plots and materials cost-benefit analysis and examining different materials which can potentially be substitutes for beryllium. A previous research paper has examined current fabrication and design techniques and also failure modes at Fermi, and this paper examines previous research in addition to emerging technologies. Many different paths have been taken by HEP Laboratories throughout the world with varying success. The history of vacuum window development is extensive and not well defined, and a matrix of what research has already been done on materials and joint design for vacuum windows will be shown. This report finally includes a treatise for vacuum window technology and a view towards emerging designs and materials and discusses future advances of research such as fabrication techniques including additive manufacturing and ultrasonic welding. Further exploration into these would prove beneficial to developing vacuum windows that are safer and stronger while being more transparent to the beam.
{"title":"Accelerator Vacuum Windows: A Review of Past Research and a Strategy for the Development of a New Design for Improved Safety and Longevity for Particle Accelerators","authors":"C. Ader, Mar Alvarez, J. Batko, R. Campos, M. McGee, A. Watts","doi":"10.18429/JACoW-IPAC2019-WEXXPLS2","DOIUrl":"https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLS2","url":null,"abstract":"Vacuum window research continues at Fermilab and this paper will examine cost effective, consistent designs which can have a huge impact on accelerator laboratories in terms of safety and cost. Issues such as the design, materials, analysis, testing and fabrication are addressed, including beam scattering plots and materials cost-benefit analysis and examining different materials which can potentially be substitutes for beryllium. A previous research paper has examined current fabrication and design techniques and also failure modes at Fermi, and this paper examines previous research in addition to emerging technologies. Many different paths have been taken by HEP Laboratories throughout the world with varying success. The history of vacuum window development is extensive and not well defined, and a matrix of what research has already been done on materials and joint design for vacuum windows will be shown. This report finally includes a treatise for vacuum window technology and a view towards emerging designs and materials and discusses future advances of research such as fabrication techniques including additive manufacturing and ultrasonic welding. Further exploration into these would prove beneficial to developing vacuum windows that are safer and stronger while being more transparent to the beam.","PeriodicalId":8436,"journal":{"name":"arXiv: Accelerator Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74174695","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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