Beam position monitors(BPMs)are important to monitor the beam moving steadily.Keeping the beam's normal motion is an important mission for Shanghai Synchrotron Radiation Facility.Effective diagnostic analysis is a...Beam position monitors(BPMs)are important to monitor the beam moving steadily.Keeping the beam's normal motion is an important mission for Shanghai Synchrotron Radiation Facility.Effective diagnostic analysis is an important way to accomplish this task.This paper develops a new method based on clustering analysis to diagnose the healthy of BPMs with basic running data,i.e.,the β oscillation of X and Y directions and noise data.The analysis results showed that all beam position monitors(140 BPMs)can be classified into three groups:normal group,worse performance group,and fault group,respectively.In addition,the abnormal BPMs(including worse performance)could be marked.The new method showed its ability to handle faulty BPMs and it could instruct daily maintenance.On the other hand,it will be a useful supplement for data analysis in accelerator physics.展开更多
The heavy-ion accelerator facility(HIAF)under construction in China will produce various stable and intense radioactive beams with energies ranging from MeV/u to GeV/u.The ion-linac(iLinac)accelerator,which will serve...The heavy-ion accelerator facility(HIAF)under construction in China will produce various stable and intense radioactive beams with energies ranging from MeV/u to GeV/u.The ion-linac(iLinac)accelerator,which will serve as the injector for the HIAF,is a superconducting heavy-ion accelerator containing 13 cryomodules.It will operate in either continuous wave mode or pulsed mode,with a beam current ranging from 0.01 to 1 emA.The beam position monitor(BPM)is crucial for this high-beam-power machine,which requires precise beam control and a very small beam loss of less than 1 W/m,especially inside the cryomodules of this unique beam instrument.Nearly 70 BPMs will be installed on the iLinac.New digital beam position and phase measurement(DBPPM)electronics based on a heterogeneous multiprocessing platform system-on-chip(MPSoC)has been developed to provide accurate beam trajectory and phase measurements as well as beam interlocking signals for a fast machine protection system(MPS).The DBPPM comprises an analog front-end(AFE)board in field programmable gate array(FPGA)mezzanine-connector(FMC)form factor,along with a digital signal processing board housed within a “2U 19”chassis.To mitigate radio frequency(RF)leakage effects from high-power RF systems in certain scenarios,beam signals undergo simultaneous processing at both fundamental and second-harmonic frequencies.A dynamic range from-65 dBm to 0 dBm was established to accommodate both weak beam commissioning and high-intensity operational demands.Laboratory tests demonstrated that at input power levels exceeding-45 d Bm,the phase resolution surpasses 0.05°,and the position resolution exceeds 5μm.These results align well with the stipulated measurement requirements.Moreover,the newly developed DBPPM has self-testing and self-calibration functions that are highly helpful for the systematic evaluation of numerous electronic components and fault diagnosis equipment.In addition,the DBPPM electronics implements a 2D nonlinear polynomial correction on the FPGA and can collect accurate real-time position measurements at large beam offsets.This newly developed DBPPM electronics has been applied to several Linac machines,and the results from beam measurements show high performance,good long-term stability,and high reliability.In this paper,a detailed overview of the architecture,performance,and proof-of-principle measurement of the beams is presented.展开更多
Beam Position Monitors（BPMs） for the low-β beam of the Chinese Accelerator Driven Subcritical system（CADS） Proton linac are of the capacitive pick-up type.They provide higher output signals than that of the induc...Beam Position Monitors（BPMs） for the low-β beam of the Chinese Accelerator Driven Subcritical system（CADS） Proton linac are of the capacitive pick-up type.They provide higher output signals than that of the inductive type.This paper will describe the design and tests of the capacitive BPM system for the low-β proton linac,including the pick-ups,the test bench and the read-out electronics.The tests done with an actual proton beam show a good agreement between the measurements and the simulations in the time domain.展开更多
Purpose The absolute beam position measurement in the booster and storage ring of the high energy photon source(HEPS)requires the offset between the electrical and mechanical centers of the beam position monitor(BPM)....Purpose The absolute beam position measurement in the booster and storage ring of the high energy photon source(HEPS)requires the offset between the electrical and mechanical centers of the beam position monitor(BPM).Method Traditionally,an RF signal is sent to an antenna or stretched wire aligned with the vacuum chamber,and the signal at each electrode is measured.Conversely,a replacement method using a vector network analyzer,which was proposed by Lambertson,does not involve mechanical alignment and can be used for electrical offset determination.Results and conclusions The electro-mechanical offsets of booster BPMs of the HEPS were measured using the Lambertson method.The result shows good agreement with the stretched wire method within a 30μm error.展开更多
In this paper, the 2-D electrostatic field software, POISSON, is used to calculate the characteristic impedance of a BPM （beam position monitor） for a high current proton linac. Furthermore, the time-domain 3-D modu...In this paper, the 2-D electrostatic field software, POISSON, is used to calculate the characteristic impedance of a BPM （beam position monitor） for a high current proton linac. Furthermore, the time-domain 3-D module of MAFIA with a beam microbunch at a varying offset from the axis is used to compute the induced voltage on the electrodes as a function of time. Finally, the effect of low β beams on the induced voltage, the sensitivity and the signal dynamic range of the BPM are discussed.展开更多
The new beam position monitor（BPM） system of the injector at the upgrade project of the Hefei Light Source（HLS II） has 19 stripline beam position monitors. Most consist of four orthogonally symmetric stripline ele...The new beam position monitor（BPM） system of the injector at the upgrade project of the Hefei Light Source（HLS II） has 19 stripline beam position monitors. Most consist of four orthogonally symmetric stripline electrodes. Differences in electronic gain and mismachining tolerance can cause changes in the beam response of the BPM electrodes. This variation will couple the two measured horizontal positions, resulting in measuring error. To alleviate this effect, a new technique to measure the relative response of the four electrodes has been developed. It is independent of the beam charge, and the related coefficient can be calculated theoretically. The effect of electrode coupling on this technique is analyzed. The calibration data is used to fit the gain for all 19 injector beam position monitors. The results show the standard deviation of the distribution of measured gains is about 5%.展开更多
Purpose Hundreds of digital beam position monitor processors(DBPM)are required to be produced during the construction of projects such as High Energy Photon Source(HEPS)and the upgrade project of the Beijing Electron ...Purpose Hundreds of digital beam position monitor processors(DBPM)are required to be produced during the construction of projects such as High Energy Photon Source(HEPS)and the upgrade project of the Beijing Electron Positron Collider(BEPCII),which brings great challenges to the test work.In order to achieve accurate,fast,and complete mass production tests of DBPMs,an automatic test system(ATS)has been developed in this article.Methods According to the test items of DBPM,the standardized testing softwareflow is designed based on virtual instru-ment program control technology and experimental physics and industrial control system(EPICS),which realize automatic adjustment of test parameters and automatic acquisition of test result data.Results and conclusions The ATS can realize one-button testing of channel coefficients,channel linearity,attenuator linearity,beam current dependence(BCD)and sampling signal-to-noise ratio(SNR),and generate test reports.The total test time is less than 3 minutes,which is significantly more efficient compared to manual testing.More than 90 BEPCII DBPMs has been tested by this ATS in the lab.The test results proved that such a system could automatically recognize defective products and satisfy the requirements of mass testing.展开更多
Automatic phase-setting is essential for modern linacs which have increasingly stringent time demands for beam tune-up and fault compensation.A key challenge in automatic phase-setting is obtaining an accurate knowled...Automatic phase-setting is essential for modern linacs which have increasingly stringent time demands for beam tune-up and fault compensation.A key challenge in automatic phase-setting is obtaining an accurate knowledge of the position and phase offsets of all cavities.This study proposes a beam-based method that employs time-of-flight experiments for simultaneous alignment and phase calibration of a superconducting hadron linac.The proposed method is verified using the CAFE2 accelerator at the Institute of Modern Physics,where offset measurements enable rapid tune-up via automatic phase-setting,and the output beam energies closely match the predicted values.The proposed method is able to address longitudinal position shifts within cryomodules due to cool-down,readily applicable to superconducting hadron linacs,and expected to be employed in the upcoming commissioning of CiADS and HIAF.展开更多
This study discusses the welding properties for the components of an aluminum-alloy ultra-high vacuum chamber and beam position monitor （BPM）.The welding parameters include the modes of laser output （pulsed wave an...This study discusses the welding properties for the components of an aluminum-alloy ultra-high vacuum chamber and beam position monitor （BPM）.The welding parameters include the modes of laser output （pulsed wave and continuous wave）,welding speed,shield gas flow,welding bead structure,and focusing distance.The results showed that the welding defect rate of the pulsed wave type was larger than that of the continuous wave type.The crack in the welding bead reduced with decreasing welding speed.The fusion penetration of the welding bead was higher when the focusing distance was long enough to deepen into the welding material.Weld morphology during the experimental process revealed the proper flow of shield gas.The adaptability design of the welding bead structure in the preceding processes had more effect on overall welding structure and morphology.展开更多
The Duke storage ring is a dedicated driver for the storage ring based oscillator free-electron lasers（FELs）, and the High Intensity Gamma-ray Source（HIGS）. It is operated with a beam current ranging from about1 m...The Duke storage ring is a dedicated driver for the storage ring based oscillator free-electron lasers（FELs）, and the High Intensity Gamma-ray Source（HIGS）. It is operated with a beam current ranging from about1 mA to 100 mA per bunch for various operations and accelerator physics studies. High performance operations of the FEL and γ-ray source require a stable electron beam orbit, which has been realized by the global orbit feedback system. As a critical part of the orbit feedback system, the electron beam position monitors（BPMs） are required to be able to precisely measure the electron beam orbit in a wide range of the single-bunch current. However, the high peak voltage of the BPM pickups associated with high single-bunch current degrades the performance of the BPM electronics, and can potentially damage the BPM electronics. A signal conditioning method using low pass filters is developed to reduce the peak voltage to protect the BPM electronics, and to make the BPMs capable of working with a wide range of single-bunch current. Simulations and electron beam based tests are performed. The results show that the Duke storage ring BPM system is capable of providing precise orbit measurements to ensure highly stable FEL and HIGS operations.展开更多
There is growing interest in utilizing the beam position monitor turn-by-turn（TBT） data to debug accelerators. TBT data can be used to determine the linear optics,coupled optics and nonlinear behaviors of the storag...There is growing interest in utilizing the beam position monitor turn-by-turn（TBT） data to debug accelerators. TBT data can be used to determine the linear optics,coupled optics and nonlinear behaviors of the storage ring lattice. This is not only a useful complement to other methods of determining the linear optics such as LOCO,but also provides a possibility to uncover more hidden phenomena. In this paper,a preliminary application of a β function measurement to the SSRF storage ring is presented.展开更多
Background In the linac of Beijing Electron Positron Collider II(BEPCII),the resolution of existing BPMs is several hundred microns.But the requirement of transverse position resolution of BPM for future top-up inject...Background In the linac of Beijing Electron Positron Collider II(BEPCII),the resolution of existing BPMs is several hundred microns.But the requirement of transverse position resolution of BPM for future top-up injection needs to be more precise.Purpose This paper is mainly concerned about the design and simulation of the cavity beam position monitor(CBPM)for BEPCII linac and free electron laser(FEL).The requirement of beam transverse position resolution for linac is several microns,even a few nanometers for FEL.Methods When the beam bunch goes through the CBPM,it can excite different electromagnetic field modes in resonator.In these modes,TM_(110) is the most sensitive to beam transverse position offset.The design of CBPM is aim to analyze the relationship between TM_(110) and beam transverse position by CST Studio and Ansys HFSS.Conclusion In this research,we design a pair of rectangular slots for position cavity to revise the direction of electromagnetic field.The simulation result of theoretical resolution is able to reach 15 nm@1nC with the operating frequency 2500 MHz.It is obviously that CBPM has more excellent resolution than all of operating BPM in BEPCII.Meanwhile,the research of CBPM improves the application of beam detection technology in BEPCII and accumulates technology for future design of HEPS and FEL.The mechanical design of the prototype is being fabricated.展开更多
基金Ten Thousand Talent Program and Chinese Academy of Sciences Key Technology Talent Program (No.Y91G201B01)。
文摘Beam position monitors(BPMs)are important to monitor the beam moving steadily.Keeping the beam's normal motion is an important mission for Shanghai Synchrotron Radiation Facility.Effective diagnostic analysis is an important way to accomplish this task.This paper develops a new method based on clustering analysis to diagnose the healthy of BPMs with basic running data,i.e.,the β oscillation of X and Y directions and noise data.The analysis results showed that all beam position monitors(140 BPMs)can be classified into three groups:normal group,worse performance group,and fault group,respectively.In addition,the abnormal BPMs(including worse performance)could be marked.The new method showed its ability to handle faulty BPMs and it could instruct daily maintenance.On the other hand,it will be a useful supplement for data analysis in accelerator physics.
基金supported by the National Natural Science Foundation of China(No.11975290)。
文摘The heavy-ion accelerator facility(HIAF)under construction in China will produce various stable and intense radioactive beams with energies ranging from MeV/u to GeV/u.The ion-linac(iLinac)accelerator,which will serve as the injector for the HIAF,is a superconducting heavy-ion accelerator containing 13 cryomodules.It will operate in either continuous wave mode or pulsed mode,with a beam current ranging from 0.01 to 1 emA.The beam position monitor(BPM)is crucial for this high-beam-power machine,which requires precise beam control and a very small beam loss of less than 1 W/m,especially inside the cryomodules of this unique beam instrument.Nearly 70 BPMs will be installed on the iLinac.New digital beam position and phase measurement(DBPPM)electronics based on a heterogeneous multiprocessing platform system-on-chip(MPSoC)has been developed to provide accurate beam trajectory and phase measurements as well as beam interlocking signals for a fast machine protection system(MPS).The DBPPM comprises an analog front-end(AFE)board in field programmable gate array(FPGA)mezzanine-connector(FMC)form factor,along with a digital signal processing board housed within a “2U 19”chassis.To mitigate radio frequency(RF)leakage effects from high-power RF systems in certain scenarios,beam signals undergo simultaneous processing at both fundamental and second-harmonic frequencies.A dynamic range from-65 dBm to 0 dBm was established to accommodate both weak beam commissioning and high-intensity operational demands.Laboratory tests demonstrated that at input power levels exceeding-45 d Bm,the phase resolution surpasses 0.05°,and the position resolution exceeds 5μm.These results align well with the stipulated measurement requirements.Moreover,the newly developed DBPPM has self-testing and self-calibration functions that are highly helpful for the systematic evaluation of numerous electronic components and fault diagnosis equipment.In addition,the DBPPM electronics implements a 2D nonlinear polynomial correction on the FPGA and can collect accurate real-time position measurements at large beam offsets.This newly developed DBPPM electronics has been applied to several Linac machines,and the results from beam measurements show high performance,good long-term stability,and high reliability.In this paper,a detailed overview of the architecture,performance,and proof-of-principle measurement of the beams is presented.
基金Supported by National Natural Science Foundation of China(11405240)"Western Light" Talents Training Program of Chinese Academy of Sciences
文摘Beam Position Monitors（BPMs） for the low-β beam of the Chinese Accelerator Driven Subcritical system（CADS） Proton linac are of the capacitive pick-up type.They provide higher output signals than that of the inductive type.This paper will describe the design and tests of the capacitive BPM system for the low-β proton linac,including the pick-ups,the test bench and the read-out electronics.The tests done with an actual proton beam show a good agreement between the measurements and the simulations in the time domain.
基金funded by the Youth Innovation Promotion Association CAS(No.2019013 and Y202005)the National Natural Science Foundation of China(No.11975254).
文摘Purpose The absolute beam position measurement in the booster and storage ring of the high energy photon source(HEPS)requires the offset between the electrical and mechanical centers of the beam position monitor(BPM).Method Traditionally,an RF signal is sent to an antenna or stretched wire aligned with the vacuum chamber,and the signal at each electrode is measured.Conversely,a replacement method using a vector network analyzer,which was proposed by Lambertson,does not involve mechanical alignment and can be used for electrical offset determination.Results and conclusions The electro-mechanical offsets of booster BPMs of the HEPS were measured using the Lambertson method.The result shows good agreement with the stretched wire method within a 30μm error.
文摘In this paper, the 2-D electrostatic field software, POISSON, is used to calculate the characteristic impedance of a BPM （beam position monitor） for a high current proton linac. Furthermore, the time-domain 3-D module of MAFIA with a beam microbunch at a varying offset from the axis is used to compute the induced voltage on the electrodes as a function of time. Finally, the effect of low β beams on the induced voltage, the sensitivity and the signal dynamic range of the BPM are discussed.
基金Supported by National Natural Science Foundation of China(11175173,11375178,11105141)
文摘The new beam position monitor（BPM） system of the injector at the upgrade project of the Hefei Light Source（HLS II） has 19 stripline beam position monitors. Most consist of four orthogonally symmetric stripline electrodes. Differences in electronic gain and mismachining tolerance can cause changes in the beam response of the BPM electrodes. This variation will couple the two measured horizontal positions, resulting in measuring error. To alleviate this effect, a new technique to measure the relative response of the four electrodes has been developed. It is independent of the beam charge, and the related coefficient can be calculated theoretically. The effect of electrode coupling on this technique is analyzed. The calibration data is used to fit the gain for all 19 injector beam position monitors. The results show the standard deviation of the distribution of measured gains is about 5%.
基金funded by the Foundation ofYouth Innovation Promotion Association,CAS(No.Y202005)the Major achievements cultivation project of major scientific and technological infrastructure,CAS(No.NE01G74Y2)the National Natural Science Foundation of China(No.11805221).
文摘Purpose Hundreds of digital beam position monitor processors(DBPM)are required to be produced during the construction of projects such as High Energy Photon Source(HEPS)and the upgrade project of the Beijing Electron Positron Collider(BEPCII),which brings great challenges to the test work.In order to achieve accurate,fast,and complete mass production tests of DBPMs,an automatic test system(ATS)has been developed in this article.Methods According to the test items of DBPM,the standardized testing softwareflow is designed based on virtual instru-ment program control technology and experimental physics and industrial control system(EPICS),which realize automatic adjustment of test parameters and automatic acquisition of test result data.Results and conclusions The ATS can realize one-button testing of channel coefficients,channel linearity,attenuator linearity,beam current dependence(BCD)and sampling signal-to-noise ratio(SNR),and generate test reports.The total test time is less than 3 minutes,which is significantly more efficient compared to manual testing.More than 90 BEPCII DBPMs has been tested by this ATS in the lab.The test results proved that such a system could automatically recognize defective products and satisfy the requirements of mass testing.
基金supported by the National Natural Science Foundation of China(U22A20261)the Large Research Infrastructures China initiative Accelerator Driven System(2017-000052-75-01-000590).
文摘Automatic phase-setting is essential for modern linacs which have increasingly stringent time demands for beam tune-up and fault compensation.A key challenge in automatic phase-setting is obtaining an accurate knowledge of the position and phase offsets of all cavities.This study proposes a beam-based method that employs time-of-flight experiments for simultaneous alignment and phase calibration of a superconducting hadron linac.The proposed method is verified using the CAFE2 accelerator at the Institute of Modern Physics,where offset measurements enable rapid tune-up via automatic phase-setting,and the output beam energies closely match the predicted values.The proposed method is able to address longitudinal position shifts within cryomodules due to cool-down,readily applicable to superconducting hadron linacs,and expected to be employed in the upcoming commissioning of CiADS and HIAF.
文摘This study discusses the welding properties for the components of an aluminum-alloy ultra-high vacuum chamber and beam position monitor （BPM）.The welding parameters include the modes of laser output （pulsed wave and continuous wave）,welding speed,shield gas flow,welding bead structure,and focusing distance.The results showed that the welding defect rate of the pulsed wave type was larger than that of the continuous wave type.The crack in the welding bead reduced with decreasing welding speed.The fusion penetration of the welding bead was higher when the focusing distance was long enough to deepen into the welding material.Weld morphology during the experimental process revealed the proper flow of shield gas.The adaptability design of the welding bead structure in the preceding processes had more effect on overall welding structure and morphology.
基金Supported by US Department of Energy(DE-FG02-97ER41033)Fundamental Research Funds for the Central Universities of China(WK2310000032)
文摘The Duke storage ring is a dedicated driver for the storage ring based oscillator free-electron lasers（FELs）, and the High Intensity Gamma-ray Source（HIGS）. It is operated with a beam current ranging from about1 mA to 100 mA per bunch for various operations and accelerator physics studies. High performance operations of the FEL and γ-ray source require a stable electron beam orbit, which has been realized by the global orbit feedback system. As a critical part of the orbit feedback system, the electron beam position monitors（BPMs） are required to be able to precisely measure the electron beam orbit in a wide range of the single-bunch current. However, the high peak voltage of the BPM pickups associated with high single-bunch current degrades the performance of the BPM electronics, and can potentially damage the BPM electronics. A signal conditioning method using low pass filters is developed to reduce the peak voltage to protect the BPM electronics, and to make the BPMs capable of working with a wide range of single-bunch current. Simulations and electron beam based tests are performed. The results show that the Duke storage ring BPM system is capable of providing precise orbit measurements to ensure highly stable FEL and HIGS operations.
文摘There is growing interest in utilizing the beam position monitor turn-by-turn（TBT） data to debug accelerators. TBT data can be used to determine the linear optics,coupled optics and nonlinear behaviors of the storage ring lattice. This is not only a useful complement to other methods of determining the linear optics such as LOCO,but also provides a possibility to uncover more hidden phenomena. In this paper,a preliminary application of a β function measurement to the SSRF storage ring is presented.
基金the Major Projects of the Ministry of Science and Technology(Grant No.2016YFA040190301).
文摘Background In the linac of Beijing Electron Positron Collider II(BEPCII),the resolution of existing BPMs is several hundred microns.But the requirement of transverse position resolution of BPM for future top-up injection needs to be more precise.Purpose This paper is mainly concerned about the design and simulation of the cavity beam position monitor(CBPM)for BEPCII linac and free electron laser(FEL).The requirement of beam transverse position resolution for linac is several microns,even a few nanometers for FEL.Methods When the beam bunch goes through the CBPM,it can excite different electromagnetic field modes in resonator.In these modes,TM_(110) is the most sensitive to beam transverse position offset.The design of CBPM is aim to analyze the relationship between TM_(110) and beam transverse position by CST Studio and Ansys HFSS.Conclusion In this research,we design a pair of rectangular slots for position cavity to revise the direction of electromagnetic field.The simulation result of theoretical resolution is able to reach 15 nm@1nC with the operating frequency 2500 MHz.It is obviously that CBPM has more excellent resolution than all of operating BPM in BEPCII.Meanwhile,the research of CBPM improves the application of beam detection technology in BEPCII and accumulates technology for future design of HEPS and FEL.The mechanical design of the prototype is being fabricated.
