分类： 物理学 >> 核物理学 提交时间： 2025-05-13
Tan, Dr. Nongchao
Wu, Prof. Ping
Sun, Prof. Jun
Hua, Dr. Ye
Zhou, Mr. Anxing
Du, Mr. Xingju
Lv, Prof. Zhongliang
Chen, Prof. Kaiguo
Zhang, Prof. shen
Huang, Prof. Wenhui
摘要： The electrons escaping from metal surfaces driven by an external electric field are invariably associated with radio-frequency breakdown of microwave systems, seriously limiting the physical performance of accelerators and electronic devices. In this paper, the influence of temperature on the field emission characteristics of metals has been investigated by using a field emission system. After a heater is installed in the field emission system, the cathode’s temperature can be adjusted from room temperature to hundreds of degrees centigrade. It is experimentally revealed that the field emission performance of titanium and oxygen-free copper is greatly improved when the temperature is increased within 100 degrees centigrade. The field-emission current of oxygen-free copper at 105℃ increases to 4.0 times its value at room temperature as the intensity of the applied electric field remains 140 kV/cm, while the field-emission current of titanium at 150℃ is 14.6 times that at room temperature under an electric field strength of 190 kV/cm. These experimental phenomena are not consistent with the traditional metal model. Afterwards, the thermal-field emission theory of dielectric microdot is introduced to reasonably explain the promotion of temperature on the field-emission characteristics of these two metals, indicating that the dielectric microdots on the surface dominate the thermal-field emission of metals. The new discovery can provide theoretical guidance for suppressing vacuum breakdown in microwave devices and accelerators.
分类： 物理学 >> 核物理学 提交时间： 2025-03-26
摘要： This study introduces a novel real-time betatron tune measurement algorithm, utilizing Schottky signals and an FPGA-based backend architecture, specifically designed for rapidly ramping synchrotrons, with particular application to the Shanghai Advanced Proton Therapy (SAPT) facility. The developed algorithm demonstrates improved measurement accuracy under challenging operational conditions, especially in scenarios with limited sampling time and signal-to-noise ratios (SNR) as low as -20 dB. By applying Short-Time Fourier Transform (STFT) analysis, the algorithm effectively accommodates the rapid increase in revolution frequency from 4 MHz to 7.5 MHz over 0.35 seconds, along with tune shifts. A macro-particle simulation methodology is employed to generate Schottky signals, which are then combined with real noise collected from an analog-to-digital converter (ADC) to simulate practical conditions. The proposed betatron tune measurement algorithm integrates advanced spectral processing techniques and an enhanced peak detection algorithm specifically tailored for low SNR conditions. Experimental validation confirms the superior performance of the proposed algorithm over conventional approaches in terms of measurement accuracy, stability, and system robustness, while meeting the stringent operational requirements of proton therapy applications. This innovative approach effectively addresses critical limitations associated with Schottky diagnostics for betatron tune measurement in rapidly ramping synchrotrons operating under low SNR conditions, laying a robust foundation and providing a viable solution for advanced applications in proton therapy and related accelerator physics fields.
分类： 核科学技术 >> 粒子加速器 提交时间： 2025-02-24
摘要： 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 (TOF) experiments to for simultaneous alignment and phase calibration of a superconducting hadron linac. The proposed method is[A1] verified using a CAFe II 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.
分类： 核科学技术 >> 粒子加速器 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
WU Fang-Fang
ZHOU Ze-Ran
YANG Yong-Liang
SUN Bao-Gen
ZOU Jun-Yin
LU Ping
CHENG Chao-Cai
LUO Qing
XU Jun
摘要： The four electrodes in the stripline beam position monitor (BPM) for Hefei Light Source (HLS II) storage ring are of axially symmetric type. We have derived a new calibration method of electrode gains for this type stripline BPM. The gain fit error of different data grids was analyzed, and the � 5 mm by � 5 mm grid is the best. The electrode gains of two stripline BPMs (HLS II SR-BD-STLB1 and HLS II SR-BD-STLB2) were obtained based on offline calibrated data. The results show that data after fitting gains are improved, with the electrode gains being between 0.94 and 1.15.
分类： 核科学技术 >> 粒子加速器 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： In this paper, in order to stabilize the position and angle of the light source point, a new photon beam position feedback system based on the Photon Beam Position Monitors was developed on Hefei Light Source, and used to correct the position drift and angle variation of the light source at the same time. On introducing the feedback principle, the transfer function matrix is calibrated, indicating that the new system is workable and effective.
分类： 物理学 >> 核物理学 提交时间： 2025-05-28
Miao, Mr. Dexing
Xu, Prof. Zijun
Xiang, Dr. Zhiyu
Liu, Dr. Pingcheng
Ambrosi, Prof. Giovanni
Barbanera, Dr. Mattia
Cai, Dr. Mengke
Cai, Prof. Xudong
Chou, Dr. Hsin-Yi
Duranti, Prof. Matteo
Formato, Dr. Valerio
Ionica, Dr. Maria
Jiang, Dr. Yaozu
Jin, Mr. LiangChengLong
Koutsenko, Dr. Vladimir
Li, Mr. Qinze
Liu, Mr. Cong
Lv, Mr. Xingjian
Oliva, Dr. Alberto
Peng, Wenxi
摘要： A silicon microstrip detector (SSD) has been developed to have state of the art spatial resolution and a large sensitive area under stringent power constraints. The design incorporates three floating strips with their bias resistors inserted between two aluminum readout strips. Beam test measurements with the single sensor confirmed that this configuration achieves a total detection efficiency of 99.8% and spatial resolution 7.6 μm for MIPs. A double-η algorithm was developed to optimize hit position reconstruction for this SSD. The design can be adapted for large area silicon detectors.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： A fully digital beam position monitoring system (DBPM) has been designed for SSRF (Shanghai Synchrotron Radiation Facility). As analog-to-digital converter (ADC) is a crucial part in the DBPM system, the sampling methods should be studied to achieve optimum performance. Different sampling modes were used and compared through tests. Long term variation among four sampling channels, which would introduce errors in beam position measurement, is studied, too. An interleaved distribution scheme was designed to address this issue. To evaluate the sampling methods, in-beam tests were conducted in SSRF. Test results indicate that with proper sampling methods, a turn-by-turn (TBT) position resolution better than 1 m is achieved, and the slow-acquisition (SA) position resolution is improved from 4.28 m to 0.17 m.
分类： 核科学技术 >> 粒子加速器 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： In this paper, in order to achieve the output signal processing of cavity beam position monitor (CBPM), we develop a digital intermediate frequency receiver architecture based signal processing system, which consists of radio frequency (RF) front end and high speed data acquisition board. The beam position resolution in the CBPM signal processing system is superior to 1 m. Two signal processing algorithms, fast Fourier transform (FFT) and digital down converter (DDC), are evaluated offline using MATLAB platform, and both can be used to achieve, the CW input signal, position resolutions of 0.31 m and 0.10 m at 16 dBm. The DDC algorithm for its good compatibility is downloaded into the FPGA to realize online measurement, reaching the position resolution of 0.49 m due to truncation error. The whole system works well and the performance meets design target.
分类： 物理学 >> 核物理学 分类： 物理学 >> 地球物理学、天文学和天体物理学 提交时间： 2016-11-25
摘要： Changes in beam position within charged particle accelerator storage rings have been observed due to changes in gravity （Δg） caused by the moon and sun. The terrestrial tidal model has been used to explain this type of beam instability. Further analysis reveals that these instabilities arise from changes in the electron beam energy, rather than from movements of the accelerator components due to terrestrial tidal forces. We suggest a potential model to better explain this type of instability. Consider a charged particle beam ring rotating with the earth, perpendicular to the moon's line of gravity. We induce an electromotive force along the ring, referred to as electro-gravitational induction (EGI). The circular motion of the charged particles causes the accumulation of the EGI in the storage ring, turn by turn. We used existing data from storage ring beam signals to estimate the maximum value of the gravity coefficient of the induced electromotive force.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： Beam current dependence resulted from nonlinearity and asymmetry of the four channels of digital BPM (Beam Position Monitor) processor deteriorates the BPM performance. A systematic solution based on signal source calibration tactics has been carried out to rectify this defect. It is optimized for implementation in FPGA. Mathematical illustrations of the calibration method, hardware and software design and implementation are presented. A signal source circuit using frequency synthesis technique is designed as calibration standard. Data acquisition system using JAVA web technology and Ethernet is introduced. Integrated FPGA implementation code architecture is presented, and experimental test results show that the method implemented in FPGA is feasible. Compared to other methods, our approach can rectify the nonlinearity and asymmetry simultaneously. The whole solution is integrated into the DBPM processor and can be executed online.
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