Continuous tracking of bunch charges is the key to maintain stable operations in a storage ring in top-up mode. Recently, a precise bunch-by-bunch beam-current measurement (BCM) system has been developed at the Shangh...Continuous tracking of bunch charges is the key to maintain stable operations in a storage ring in top-up mode. Recently, a precise bunch-by-bunch beam-current measurement (BCM) system has been developed at the Shanghai Synchrotron Radiation Facility. To avoid the influence of longitudinal oscillation on the amplitudes of the sampling points, a method called two-point equilibrium sampling is introduced. The results, obtained during routine operation time, show that the relative resolution of the measurement of the bunch charges is better than 0.02%. With this high resolution, the new BCM system is able to monitor the bunch-by-bunch beam lifetime. By using the filling pattern information, the Touschek lifetime and the vacuum lifetime can also be calculated. In this paper, the principle of the new method and the experiments is presented in detail.展开更多
The stabilities of the beam and machine have almost the highest priority in a modern light source. Although a lot of machine parameters could be used to represent the beam quality, there is no single parameter that co...The stabilities of the beam and machine have almost the highest priority in a modern light source. Although a lot of machine parameters could be used to represent the beam quality, there is no single parameter that could indicate the global information for the machine operators and accelerator physicists. For the last few years, a new parameter has been studied as a beam quality flag in the Shanghai Synchrotron Radiation Facility （SSRF）. Calculations, simulations and detailed analysis of the real-time data from the storage ring have been made and the interesting results have confirmed its feasibility.展开更多
Beam lifetime is dominated by Touschek scattering at the Shanghai Synchrotron Radiation Facility(SSRF).Touschek loss rate is affected by probability for scattering beyond the RF acceptance and the volume charge densit...Beam lifetime is dominated by Touschek scattering at the Shanghai Synchrotron Radiation Facility(SSRF).Touschek loss rate is affected by probability for scattering beyond the RF acceptance and the volume charge density of the bench.In the phaseⅡupgrade of the SSRF,a third harmonic superconducting cavity will be used to enhance the Touschek lifetime by lengthening the bunches.The Touschek lifetime improvement factor is affected by the voltage of a harmonic cavity.To stabilize the cavity voltage,a tuning control system was designed to control it.The design of the tuning control system was based on the SSRF third-generation low-level RF control system.Some hardware and specialized algorithms were redesigned to fit the harmonic cavity control.The design of the tuning control system is complete,and the control system has been tested.The test result shows that the fluctuation of amplitude is<±0.34%within 1.5 h,which satisfies the stability requirement.展开更多
New-generation synchrotron light sources are being designed and operated worldwide to provide brighter radiation by reducing the beam emittance to X-ray diffraction limits.Intra-beam scattering(IBS)and Touschek scatte...New-generation synchrotron light sources are being designed and operated worldwide to provide brighter radiation by reducing the beam emittance to X-ray diffraction limits.Intra-beam scattering(IBS)and Touschek scattering in such facilities are significant and require attention because of their ultra-low emittance.Therefore,cure strategies need to be carefully studied to obtain highquality photon beams.For the Shanghai Synchrotron Radiation Facility Upgrade(SSRF-U),a candidate lattice of the storage ring,reaching the soft X-ray diffraction limit,was designed and presented for the first time in this study.The emittance growth and beam lifetime in the SSRF-U storage ring were studied using particle simulations for a series of different machine configurations.The gains with RF frequencies of 100 MHz and 500 MHz were compared.Along with a better filling pattern,a more suitable RF frequency was adopted in the SSRF-U.The variations in the equilibrium beam emittance with beam coupling and bunch-lengthening were identified using simulations.Optimal beam coupling and required bunch-lengthening for the SSRF-U storage ring were thus determined.The fitness of the beam energy in the SSRF-U was subsequently assessed using the obtained parameters.Additionally,the Touschek scattering and beam lifetime were calculated,and an acceptable total beam lifetime was obtained.展开更多
Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy...Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy physics in the last two decades,a new-generation Tau-Charm factory,called the Super Tau-Charm Facility(STCF),has been actively promoted by the particle physics community in China.STCF has the potential to address fundamental questions such as the essence of color confinement and the matter-antimatter asymmetry within the next decades.The main design goals of the STCF are a center-of-mass energy ranging from 2 to 7 GeV and a luminosity surpassing 5×10^(34)cm^(−2)s^(−1)that is optimized at a center-of-mass energy of 4 GeV,which is approximately 50 times that of the currently operating Tau-Charm factory-BEPCII.The STCF accelerator has two main parts:a double-ring collider with a crab-waist collision scheme and an injector that provides top-up injections for both electron and positron beams.As a typical third-generation electron-positron circular collider,the STCF accelerator faces many challenges in both accelerator physics and technology.In this paper,the conceptual design of the STCF accelerator complex is presented,including the ongoing efforts and plans for technological research and develop-ment,as well as the required infrastructure.The STCF project aims to secure support from the Chinese central government for its construction during the 15th Five-Year Plan(2026-2030).展开更多
Hefei Light Source （HLS） is being upgraded to HLS Ⅱ. Its emittance will be much lower than before, therefore the Touschek scattering will increase significantly and become the dominant factor of beam loss. So it is...Hefei Light Source （HLS） is being upgraded to HLS Ⅱ. Its emittance will be much lower than before, therefore the Touschek scattering will increase significantly and become the dominant factor of beam loss. So it is necessary to build a new beam loss monitoring （BLM） system that, in contrast to the old one, is able to obtain the quantity and position information of lost electrons. This information is useful in the commissioning, troubleshooting, and beam lifetime studying for HLS Ⅱ. This paper analyzes the distribution features of different kinds of lost electrons, introduces the operation parameters of the new machine and discusses how to choose proper monitoring positions. Based on these comprehensive analyses, a new BLM system for HLS Ⅱ is proposed.展开更多
In an electron storage ring, the bunch length can be increased or decreased by using harmonic cavities. Taking the High Energy Photon Source as an example, we test the bunch length manipulation with harmonic cavities ...In an electron storage ring, the bunch length can be increased or decreased by using harmonic cavities. Taking the High Energy Photon Source as an example, we test the bunch length manipulation with harmonic cavities in a diffraction-limited storage ring （DLSR）. The most important collective effects in a DLSR, intra-beam scattering and Touschek effects, are evaluated for different bunch-length patterns. Our study shows that it is feasible to produce long and short bunches simultaneously in a DLSR, without causing severe emittance growth and reduction in lifetime.展开更多
基金supported by the National Natural Science Foundation of China(No.11575282)the Ten Thousand Talent Program
文摘Continuous tracking of bunch charges is the key to maintain stable operations in a storage ring in top-up mode. Recently, a precise bunch-by-bunch beam-current measurement (BCM) system has been developed at the Shanghai Synchrotron Radiation Facility. To avoid the influence of longitudinal oscillation on the amplitudes of the sampling points, a method called two-point equilibrium sampling is introduced. The results, obtained during routine operation time, show that the relative resolution of the measurement of the bunch charges is better than 0.02%. With this high resolution, the new BCM system is able to monitor the bunch-by-bunch beam lifetime. By using the filling pattern information, the Touschek lifetime and the vacuum lifetime can also be calculated. In this paper, the principle of the new method and the experiments is presented in detail.
基金Supported by National Natural Science Foundation of China(11075198)
文摘The stabilities of the beam and machine have almost the highest priority in a modern light source. Although a lot of machine parameters could be used to represent the beam quality, there is no single parameter that could indicate the global information for the machine operators and accelerator physicists. For the last few years, a new parameter has been studied as a beam quality flag in the Shanghai Synchrotron Radiation Facility （SSRF）. Calculations, simulations and detailed analysis of the real-time data from the storage ring have been made and the interesting results have confirmed its feasibility.
文摘Beam lifetime is dominated by Touschek scattering at the Shanghai Synchrotron Radiation Facility(SSRF).Touschek loss rate is affected by probability for scattering beyond the RF acceptance and the volume charge density of the bench.In the phaseⅡupgrade of the SSRF,a third harmonic superconducting cavity will be used to enhance the Touschek lifetime by lengthening the bunches.The Touschek lifetime improvement factor is affected by the voltage of a harmonic cavity.To stabilize the cavity voltage,a tuning control system was designed to control it.The design of the tuning control system was based on the SSRF third-generation low-level RF control system.Some hardware and specialized algorithms were redesigned to fit the harmonic cavity control.The design of the tuning control system is complete,and the control system has been tested.The test result shows that the fluctuation of amplitude is<±0.34%within 1.5 h,which satisfies the stability requirement.
基金The authors would like to thank Dr.Na Wang and Sai-Ke Tian in IHEP for their useful discussions.
文摘New-generation synchrotron light sources are being designed and operated worldwide to provide brighter radiation by reducing the beam emittance to X-ray diffraction limits.Intra-beam scattering(IBS)and Touschek scattering in such facilities are significant and require attention because of their ultra-low emittance.Therefore,cure strategies need to be carefully studied to obtain highquality photon beams.For the Shanghai Synchrotron Radiation Facility Upgrade(SSRF-U),a candidate lattice of the storage ring,reaching the soft X-ray diffraction limit,was designed and presented for the first time in this study.The emittance growth and beam lifetime in the SSRF-U storage ring were studied using particle simulations for a series of different machine configurations.The gains with RF frequencies of 100 MHz and 500 MHz were compared.Along with a better filling pattern,a more suitable RF frequency was adopted in the SSRF-U.The variations in the equilibrium beam emittance with beam coupling and bunch-lengthening were identified using simulations.Optimal beam coupling and required bunch-lengthening for the SSRF-U storage ring were thus determined.The fitness of the beam energy in the SSRF-U was subsequently assessed using the obtained parameters.Additionally,the Touschek scattering and beam lifetime were calculated,and an acceptable total beam lifetime was obtained.
基金supported by the National Key Research and Development Program of China(No.2022YFA1602200)the National Natural Science Foundation of China(Nos.12341501 and 12405174)the Hefei Comprehensive National Science Center for the strong support on the STCF key technology research project.
文摘Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy physics in the last two decades,a new-generation Tau-Charm factory,called the Super Tau-Charm Facility(STCF),has been actively promoted by the particle physics community in China.STCF has the potential to address fundamental questions such as the essence of color confinement and the matter-antimatter asymmetry within the next decades.The main design goals of the STCF are a center-of-mass energy ranging from 2 to 7 GeV and a luminosity surpassing 5×10^(34)cm^(−2)s^(−1)that is optimized at a center-of-mass energy of 4 GeV,which is approximately 50 times that of the currently operating Tau-Charm factory-BEPCII.The STCF accelerator has two main parts:a double-ring collider with a crab-waist collision scheme and an injector that provides top-up injections for both electron and positron beams.As a typical third-generation electron-positron circular collider,the STCF accelerator faces many challenges in both accelerator physics and technology.In this paper,the conceptual design of the STCF accelerator complex is presented,including the ongoing efforts and plans for technological research and develop-ment,as well as the required infrastructure.The STCF project aims to secure support from the Chinese central government for its construction during the 15th Five-Year Plan(2026-2030).
基金Supported by National Natural Science Foundation of China(11175180,11175182)
文摘Hefei Light Source （HLS） is being upgraded to HLS Ⅱ. Its emittance will be much lower than before, therefore the Touschek scattering will increase significantly and become the dominant factor of beam loss. So it is necessary to build a new beam loss monitoring （BLM） system that, in contrast to the old one, is able to obtain the quantity and position information of lost electrons. This information is useful in the commissioning, troubleshooting, and beam lifetime studying for HLS Ⅱ. This paper analyzes the distribution features of different kinds of lost electrons, introduces the operation parameters of the new machine and discusses how to choose proper monitoring positions. Based on these comprehensive analyses, a new BLM system for HLS Ⅱ is proposed.
基金Supported by National Natural Science Foundation of China(11475202,11405187)Youth Innovation Promotion Association of Chinese Academy of Sciences(2015009)
文摘In an electron storage ring, the bunch length can be increased or decreased by using harmonic cavities. Taking the High Energy Photon Source as an example, we test the bunch length manipulation with harmonic cavities in a diffraction-limited storage ring （DLSR）. The most important collective effects in a DLSR, intra-beam scattering and Touschek effects, are evaluated for different bunch-length patterns. Our study shows that it is feasible to produce long and short bunches simultaneously in a DLSR, without causing severe emittance growth and reduction in lifetime.
