The China Spallation Neutron Source(CSNS) upgrade project(CSNS-Ⅱ) aims to enhance the beam power from 100 to 500 kW. A dual-harmonic accelerating method has been adopted to alleviate the stronger space-charge effect ...The China Spallation Neutron Source(CSNS) upgrade project(CSNS-Ⅱ) aims to enhance the beam power from 100 to 500 kW. A dual-harmonic accelerating method has been adopted to alleviate the stronger space-charge effect in rapid-cycling synchrotrons owing to the increased beam intensity. To satisfy the requirements of dual-harmonic acceleration, a new radiofrequency(RF) system based on a magnetic alloy-loaded cavity is proposed. This paper presents design considerations and experimental results regarding the performance evaluation of the proposed RF system through high-power tests and beam commissioning. The test results demonstrate that the RF system satisfies the desired specifications and affords significant benefits for CSNS-Ⅱ.展开更多
Low-level radio frequency(LLRF)systems stabilize the electromagnetic field in the RF cavities used for beam acceleration in particle accelerators.Reliable,accurate,and precise detection of RF amplitude and phase is pa...Low-level radio frequency(LLRF)systems stabilize the electromagnetic field in the RF cavities used for beam acceleration in particle accelerators.Reliable,accurate,and precise detection of RF amplitude and phase is particularly important to achieve high field stability for pulsed accelerators of free-electron lasers(FEL).The digital LLRF systems employ analog-to-digital converters to sample the frequency down-converted RF signal and use digital demodulation algorithms to calculate the RF amplitude and phase.Different sampling strategies and demodulation algorithms have been developed for these purposes and are introduced in this paper.This article focuses on advanced topics concerning RF detection,including accurate RF transient measurement,wideband RF detection,and RF detection with an asynchronous trigger,local oscillator,or clock.The analysis is based on the SwissFEL measurements,but the algorithms introduced are general for RF signal detection in particle accelerators.展开更多
A longitudinal accumulation scheme based on a triple-frequency RF system,in which the static radio frequency(RF)bucket is lengthened to be compatible with the realizable raise time of a fast pulse kicker,is proposed i...A longitudinal accumulation scheme based on a triple-frequency RF system,in which the static radio frequency(RF)bucket is lengthened to be compatible with the realizable raise time of a fast pulse kicker,is proposed in this paper.With this technique,the bunch from a booster can be captured by the longitudinal acceptance without any disturbance to the stored bunch,which remains at the center.This composite RF system consists of three different frequencies,which can be regarded as the conventional bunch lengthening RF system(usually containing fundamental and third harmonic cavities)extended by an additional second harmonic RF cavity.In this paper,we discuss the RF jitter and the transverse mode-coupling instability(TMCI)when using this special RF system.Considering several different bunch profiles,we discuss the beam stability with regard to the RF jitter.However,for the TMCI we assume an ideal bunch profile,where the bunch is exactly lengthened to the maximum extent.While macroparticle simulation is the main method used to study the impact of the RF jitter,numerical analysis and simulations for the TMCI while using a triple-frequency RF system are also presented in this paper.An approximation formula,based on the existing model,is also derived to estimate the impact of the TMCI on the single bunch current threshold when using harmonic cavities.展开更多
The RF system for TESLA requires a comprehensive interlock system.Usually interlock systems are organized in a hierarchical way,In order to react to different fault conditions in a fast and flexible manner a nonhierar...The RF system for TESLA requires a comprehensive interlock system.Usually interlock systems are organized in a hierarchical way,In order to react to different fault conditions in a fast and flexible manner a nonhierarchical organization seems to be the better solution ,At the TESLA Test Facility (TTF) at DESY we will install a nonhierarchical interlock system that is based on user desgned reprogrammable gate-arrays (FPGA's) which incorporate an embedded microcontroller system.This system could beused later for the TESLA linear collider replacing a strictly hierarchical design.展开更多
Nowadays, we are witnessing an era marked by the autonomy of wireless devices and sensor networks without the aid of batteries. RF energy harvesting therefore becomes a promising alternative for battery dependence. Th...Nowadays, we are witnessing an era marked by the autonomy of wireless devices and sensor networks without the aid of batteries. RF energy harvesting therefore becomes a promising alternative for battery dependence. This work presents the design of an RF energy harvesting system consisting mainly of a rectenna (antenna and rectification circuit) and an adaptation circuit. First of all, we designed two dipole type antennas. One operates in the GSM 900 MHz band and the other in the GSM 1800 MHz band. The performances of the proposed antennas are provided by the ANSYS HFSS software. Secondly, we proposed two rectification circuits in order to obtain conversion efficiencies at 0 dBm of 64% for the system operating at the frequency of 900 MHz and 37% for the system at the frequency of 1800 MHz RF-DC. The rectifiers used are based on Schottky diodes. For maximum transfer of power between the antenna and the rectification circuit, L-type matching circuits have been proposed. This rectifier offers DC voltage values of 806 mV for the circuit at the frequency of 900 MHz and 616 mV for the circuit at the frequency of 1800 MHz. The adaptation circuits are obtained by carrying out simulations on the ADS (Advanced Design System) software.展开更多
In this paper,we investigate a Recofigurable Intelligent Surface(RIS)-assisted Free-Space Optics-Radio Frequency(FSO-RF)mixed dual-hop communication system for Unmanned Aerial Vehicles(UAVs).In the first hop,a source ...In this paper,we investigate a Recofigurable Intelligent Surface(RIS)-assisted Free-Space Optics-Radio Frequency(FSO-RF)mixed dual-hop communication system for Unmanned Aerial Vehicles(UAVs).In the first hop,a source UAV transmits data to a relay UAV using the FSO technique.In the second hop,the relay UAV forwards data to a destination Mobile Station(MS)via an RF channel,with the RIS enhancing coverage and performance.The relay UAV operates in a Decode-and-Forward(DF)mode.As the main contribution,we provide a mathematical performance analysis of the RIS-assisted FSO-RF mixed dual-hop UAV system,evaluating outage probability,Bit-Error Rate(BER),and average capacity.The analysis accounts for factors such as atmospheric attenuation,turbulence,geometric losses,and link interruptions caused by UAV hovering behaviors.To the best of our knowledge,this is the first theoretical investigation of RIS-assisted FSO-RF mixed dual-hop UAV communication systems.Our analytical results show strong agreement with Monte Carlo simulation outcomes.Furthermore,simulation results demonstrate that RIS significantly enhances the performance of UAV-aided mixed RF/FSO systems,although performance saturation is observed due to uncertainties stemming from UAV hovering behavior.展开更多
Organosilicone thin films were prepared through plasma polymerization(pp)in a plasma enhance chemical vapour deposition(PECVD)system,utilizing hexamethyldisilazane(HMDSN)as a monomer precursor,at varying distances(25 ...Organosilicone thin films were prepared through plasma polymerization(pp)in a plasma enhance chemical vapour deposition(PECVD)system,utilizing hexamethyldisilazane(HMDSN)as a monomer precursor,at varying distances(25 mm,35 mm,45 mm,55 mm,and 65 mm)from the plasma source to the substrate.Research has examined how the distance between the substrate and plasma source impacts the properties of thin films,including their thickness,surface morphology,and photoluminescence(PL).It was discovered that as the distance increased,both film thickness and PL intensity also increased.Additionally,the film was observed to be more uniform and smoother when deposited 45 mm below the plasma source.展开更多
The BEPC RF system has been changed to superconducting cavities during the last four years.In the Summer of 2006,the high power test had been successfully carried.In November,the East RF was put into commis- sioning.T...The BEPC RF system has been changed to superconducting cavities during the last four years.In the Summer of 2006,the high power test had been successfully carried.In November,the East RF was put into commis- sioning.The SRF system above 1.0MV voltage has been reached with the e^+/e^- collision beam over 100mA,and the beam current improved to 2.5GeV/250mA with 100kW beam power.The beam test shows the good matching of the RF parameters with measuring value and theoretic calculation.The commissioning and the high power test will be presented in this paper.展开更多
The development of a high performance wideband radio frequency （RF） transceiver used in the next generation mobile communication system is presented. The developed RF transceiver operates in the 6 to 6.3 GHz band an...The development of a high performance wideband radio frequency （RF） transceiver used in the next generation mobile communication system is presented. The developed RF transceiver operates in the 6 to 6.3 GHz band and the channel bandwidth is up to 100 MHz. It operates in the time division duplex （TDD） mode and supports the multiple-input multipleoutput （MIMO） technique for the international mobile telecommunications （IMT）-advanced systems. The classical superheterodyne scheme is employed to achieve optimal performance. Design issues of the essential components such as low noise amplifier, power amplifier and local oscillators are described in detail. Measurement results show that the maximum linear output power of the RF transceiver is above 23 dBm, and the gain and noise figure of the low noise amplifier is around 24 dB and below 1 dB, respectively. Furthermore, the error vector magnitude （EVM） measurement shows that the performance of the developed RF transceiver is well beyond the requirements of the long term evolution （LTE）-advanced system. With up to 8 x 8 MIMO configuration, the RF transceiver supports more than a 1 Gbit/s data rate in field tests.展开更多
Most synchrotron light storage rings are equipped with a higher harmonic cavity(HHC)and are currently predominantly used to increase beam life.With the enhancement of the beam current intensity,it is necessary to cons...Most synchrotron light storage rings are equipped with a higher harmonic cavity(HHC)and are currently predominantly used to increase beam life.With the enhancement of the beam current intensity,it is necessary to consider instability problems that may be caused by heavy beam loading effects.In this study,we incorporated a HHC into the small-signal Pedersen mathematical model and used system signal analysis to investigate the mode-zero Robinson instability driven by the passive superconducting harmonic cavity and active superconducting harmonic cavity fundamental modes.To further study and alleviate this instability,we introduced direct radio-frequency feedback,an automatic voltage control loop,and a phase-lock loop into the model,discussed the impact of the feedback loop parameter settings on the stability margin,and provided suggestions for parameter settings.展开更多
Purpose Digital low-level radio frequency(LLRF)system has been proposed for 166.6 MHz superconducting cavities at High Energy Photon Source.The RF field inside the cavities has to be controlled better than 0.03%(rms)i...Purpose Digital low-level radio frequency(LLRF)system has been proposed for 166.6 MHz superconducting cavities at High Energy Photon Source.The RF field inside the cavities has to be controlled better than 0.03%(rms)in amplitude and 0.03°(rms)in phase.A RF front end system is required to transform the RF signal from the cavity to IF signal before inputting into the digital signal processing(DSP)board,and up-convert the IF signal back to RF to drive the power amplifier.Methods Connectorized off-the-shelf microwave components were used to realize the RF front end system.The local oscillator generation and distribution,choices of main components and design of down-/up-conversion channels have been elaborated in detail with a focus on minimizing nonlinearity and signal interferences among channels with optimized signal distribution loss.Results and conclusions The RF front end has been incorporated with the existing DSP board and tested on a warm 166.6 MHz cavity in the laboratory.Excellent channel isolations and good linearities were achieved on the RF front end system.The RF field inside the cavity was controlled with a residual noise of 0.004%(rms)in amplitude and 0.002°(rms)in phase,well below the HEPS specifications.The sensitivity to ambient environment changes have also been studied and presented in this paper.This demonstrates a first high-performance 166.6 MHz RF front end system and provides valuable insights into HEPS LLRF system development in the future.展开更多
To study the new RF control methods, a mathematic model of the RF system for the normal conducting linac is built and implemented with the software of Matlab. The model contains some typical units of the RF system, su...To study the new RF control methods, a mathematic model of the RF system for the normal conducting linac is built and implemented with the software of Matlab. The model contains some typical units of the RF system, such as the klystron, the SLED and the traveling wave accelerating tube. Finally, the model is used to study the working point of the SLED and the adaptive feed forward algorithm for the RF control system. Simulation shows that the model works well as expected.展开更多
基金This work was supported by funds from the National Natural Science Foundation of China(Nos.11875270,U1832210,12205317)Youth Innovation Promotion Association CAS(No.2018015)Guangdong Basic and Applied Basic Research Foundation(No.2019B1515120046).
文摘The China Spallation Neutron Source(CSNS) upgrade project(CSNS-Ⅱ) aims to enhance the beam power from 100 to 500 kW. A dual-harmonic accelerating method has been adopted to alleviate the stronger space-charge effect in rapid-cycling synchrotrons owing to the increased beam intensity. To satisfy the requirements of dual-harmonic acceleration, a new radiofrequency(RF) system based on a magnetic alloy-loaded cavity is proposed. This paper presents design considerations and experimental results regarding the performance evaluation of the proposed RF system through high-power tests and beam commissioning. The test results demonstrate that the RF system satisfies the desired specifications and affords significant benefits for CSNS-Ⅱ.
文摘Low-level radio frequency(LLRF)systems stabilize the electromagnetic field in the RF cavities used for beam acceleration in particle accelerators.Reliable,accurate,and precise detection of RF amplitude and phase is particularly important to achieve high field stability for pulsed accelerators of free-electron lasers(FEL).The digital LLRF systems employ analog-to-digital converters to sample the frequency down-converted RF signal and use digital demodulation algorithms to calculate the RF amplitude and phase.Different sampling strategies and demodulation algorithms have been developed for these purposes and are introduced in this paper.This article focuses on advanced topics concerning RF detection,including accurate RF transient measurement,wideband RF detection,and RF detection with an asynchronous trigger,local oscillator,or clock.The analysis is based on the SwissFEL measurements,but the algorithms introduced are general for RF signal detection in particle accelerators.
文摘A longitudinal accumulation scheme based on a triple-frequency RF system,in which the static radio frequency(RF)bucket is lengthened to be compatible with the realizable raise time of a fast pulse kicker,is proposed in this paper.With this technique,the bunch from a booster can be captured by the longitudinal acceptance without any disturbance to the stored bunch,which remains at the center.This composite RF system consists of three different frequencies,which can be regarded as the conventional bunch lengthening RF system(usually containing fundamental and third harmonic cavities)extended by an additional second harmonic RF cavity.In this paper,we discuss the RF jitter and the transverse mode-coupling instability(TMCI)when using this special RF system.Considering several different bunch profiles,we discuss the beam stability with regard to the RF jitter.However,for the TMCI we assume an ideal bunch profile,where the bunch is exactly lengthened to the maximum extent.While macroparticle simulation is the main method used to study the impact of the RF jitter,numerical analysis and simulations for the TMCI while using a triple-frequency RF system are also presented in this paper.An approximation formula,based on the existing model,is also derived to estimate the impact of the TMCI on the single bunch current threshold when using harmonic cavities.
文摘The RF system for TESLA requires a comprehensive interlock system.Usually interlock systems are organized in a hierarchical way,In order to react to different fault conditions in a fast and flexible manner a nonhierarchical organization seems to be the better solution ,At the TESLA Test Facility (TTF) at DESY we will install a nonhierarchical interlock system that is based on user desgned reprogrammable gate-arrays (FPGA's) which incorporate an embedded microcontroller system.This system could beused later for the TESLA linear collider replacing a strictly hierarchical design.
文摘Nowadays, we are witnessing an era marked by the autonomy of wireless devices and sensor networks without the aid of batteries. RF energy harvesting therefore becomes a promising alternative for battery dependence. This work presents the design of an RF energy harvesting system consisting mainly of a rectenna (antenna and rectification circuit) and an adaptation circuit. First of all, we designed two dipole type antennas. One operates in the GSM 900 MHz band and the other in the GSM 1800 MHz band. The performances of the proposed antennas are provided by the ANSYS HFSS software. Secondly, we proposed two rectification circuits in order to obtain conversion efficiencies at 0 dBm of 64% for the system operating at the frequency of 900 MHz and 37% for the system at the frequency of 1800 MHz RF-DC. The rectifiers used are based on Schottky diodes. For maximum transfer of power between the antenna and the rectification circuit, L-type matching circuits have been proposed. This rectifier offers DC voltage values of 806 mV for the circuit at the frequency of 900 MHz and 616 mV for the circuit at the frequency of 1800 MHz. The adaptation circuits are obtained by carrying out simulations on the ADS (Advanced Design System) software.
基金supported in part by the National Research Foundation of Korea(NRF)funded by the Korea government(MSIT)under Grant NRF-2022R1I1A3073740in part by the MSIT(Ministry of Science and ICT),Korea,under the ITRC(Information Technology Research Center)support program(IITP-2024-RS-2024-00436406)supervised by the IITP(Institute for Information&Communications Technology Planning&Evaluation)+1 种基金in part by the Institute for Information and Communications Technology Promotion(IITP)Grant funded by the Korea Government(MSIP,Development of Cube Satellites Based on Core Technologies in Low Earth Orbit Satellite Communications)under Grant RS-2024-00396992in part by the Korea Research Institute for Defense Technology planning and advancement(KRIT)grant,funded by the Korea government(DAPA(Defense Acquisition Program Administration))(21-106-A00-007,Space-Layer Intelligent Communication Network Laboratory,2022).
文摘In this paper,we investigate a Recofigurable Intelligent Surface(RIS)-assisted Free-Space Optics-Radio Frequency(FSO-RF)mixed dual-hop communication system for Unmanned Aerial Vehicles(UAVs).In the first hop,a source UAV transmits data to a relay UAV using the FSO technique.In the second hop,the relay UAV forwards data to a destination Mobile Station(MS)via an RF channel,with the RIS enhancing coverage and performance.The relay UAV operates in a Decode-and-Forward(DF)mode.As the main contribution,we provide a mathematical performance analysis of the RIS-assisted FSO-RF mixed dual-hop UAV system,evaluating outage probability,Bit-Error Rate(BER),and average capacity.The analysis accounts for factors such as atmospheric attenuation,turbulence,geometric losses,and link interruptions caused by UAV hovering behaviors.To the best of our knowledge,this is the first theoretical investigation of RIS-assisted FSO-RF mixed dual-hop UAV communication systems.Our analytical results show strong agreement with Monte Carlo simulation outcomes.Furthermore,simulation results demonstrate that RIS significantly enhances the performance of UAV-aided mixed RF/FSO systems,although performance saturation is observed due to uncertainties stemming from UAV hovering behavior.
基金the AECS for its financial support of this study
文摘Organosilicone thin films were prepared through plasma polymerization(pp)in a plasma enhance chemical vapour deposition(PECVD)system,utilizing hexamethyldisilazane(HMDSN)as a monomer precursor,at varying distances(25 mm,35 mm,45 mm,55 mm,and 65 mm)from the plasma source to the substrate.Research has examined how the distance between the substrate and plasma source impacts the properties of thin films,including their thickness,surface morphology,and photoluminescence(PL).It was discovered that as the distance increased,both film thickness and PL intensity also increased.Additionally,the film was observed to be more uniform and smoother when deposited 45 mm below the plasma source.
文摘The BEPC RF system has been changed to superconducting cavities during the last four years.In the Summer of 2006,the high power test had been successfully carried.In November,the East RF was put into commis- sioning.The SRF system above 1.0MV voltage has been reached with the e^+/e^- collision beam over 100mA,and the beam current improved to 2.5GeV/250mA with 100kW beam power.The beam test shows the good matching of the RF parameters with measuring value and theoretic calculation.The commissioning and the high power test will be presented in this paper.
基金The National Natural Science Foundation of China (No.60702027,60921063)the National Basic Research Program of China(973 Program)(No.2010CB327400)the National Science and Technology Major Project of Ministry of Science and Technology of China(No.2010ZX03007-001-01,2011ZX03004-001)
文摘The development of a high performance wideband radio frequency （RF） transceiver used in the next generation mobile communication system is presented. The developed RF transceiver operates in the 6 to 6.3 GHz band and the channel bandwidth is up to 100 MHz. It operates in the time division duplex （TDD） mode and supports the multiple-input multipleoutput （MIMO） technique for the international mobile telecommunications （IMT）-advanced systems. The classical superheterodyne scheme is employed to achieve optimal performance. Design issues of the essential components such as low noise amplifier, power amplifier and local oscillators are described in detail. Measurement results show that the maximum linear output power of the RF transceiver is above 23 dBm, and the gain and noise figure of the low noise amplifier is around 24 dB and below 1 dB, respectively. Furthermore, the error vector magnitude （EVM） measurement shows that the performance of the developed RF transceiver is well beyond the requirements of the long term evolution （LTE）-advanced system. With up to 8 x 8 MIMO configuration, the RF transceiver supports more than a 1 Gbit/s data rate in field tests.
文摘Most synchrotron light storage rings are equipped with a higher harmonic cavity(HHC)and are currently predominantly used to increase beam life.With the enhancement of the beam current intensity,it is necessary to consider instability problems that may be caused by heavy beam loading effects.In this study,we incorporated a HHC into the small-signal Pedersen mathematical model and used system signal analysis to investigate the mode-zero Robinson instability driven by the passive superconducting harmonic cavity and active superconducting harmonic cavity fundamental modes.To further study and alleviate this instability,we introduced direct radio-frequency feedback,an automatic voltage control loop,and a phase-lock loop into the model,discussed the impact of the feedback loop parameter settings on the stability margin,and provided suggestions for parameter settings.
基金supported by the High Energy Photon Source-Test Facility(HEPS-TF)projectPioneer"Hundred Talents Program of Chinese Academy of Sciences
文摘Purpose Digital low-level radio frequency(LLRF)system has been proposed for 166.6 MHz superconducting cavities at High Energy Photon Source.The RF field inside the cavities has to be controlled better than 0.03%(rms)in amplitude and 0.03°(rms)in phase.A RF front end system is required to transform the RF signal from the cavity to IF signal before inputting into the digital signal processing(DSP)board,and up-convert the IF signal back to RF to drive the power amplifier.Methods Connectorized off-the-shelf microwave components were used to realize the RF front end system.The local oscillator generation and distribution,choices of main components and design of down-/up-conversion channels have been elaborated in detail with a focus on minimizing nonlinearity and signal interferences among channels with optimized signal distribution loss.Results and conclusions The RF front end has been incorporated with the existing DSP board and tested on a warm 166.6 MHz cavity in the laboratory.Excellent channel isolations and good linearities were achieved on the RF front end system.The RF field inside the cavity was controlled with a residual noise of 0.004%(rms)in amplitude and 0.002°(rms)in phase,well below the HEPS specifications.The sensitivity to ambient environment changes have also been studied and presented in this paper.This demonstrates a first high-performance 166.6 MHz RF front end system and provides valuable insights into HEPS LLRF system development in the future.
文摘To study the new RF control methods, a mathematic model of the RF system for the normal conducting linac is built and implemented with the software of Matlab. The model contains some typical units of the RF system, such as the klystron, the SLED and the traveling wave accelerating tube. Finally, the model is used to study the working point of the SLED and the adaptive feed forward algorithm for the RF control system. Simulation shows that the model works well as expected.
