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A broad-band sub-harmonic mixer for W-band applications 被引量:2
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作者 许正彬 钱澄 《Journal of Southeast University(English Edition)》 EI CAS 2013年第1期7-10,共4页
In order to improve the bandwidth of the conventional sub-harmonic mixer, a broad-band, high intermediate frequency(IF) sub-harmonic mixer for W-band applications is proposed. Replacing the open and short stubs that... In order to improve the bandwidth of the conventional sub-harmonic mixer, a broad-band, high intermediate frequency(IF) sub-harmonic mixer for W-band applications is proposed. Replacing the open and short stubs that are used in the convertional sub-harmonic mixer with a broad-band band-pass filter and a low-pass filter, respectively, a wide operating frequency band is achieved. Furthermore, without the use of the edge-coupled band-pass filter at radio frequency(RF) port, the proposed structure can be realized by common hybrid microwave integrated circuit technology at W- band. The measured results show that the proposed subharmonic mixer can operate from 80 to 107.5 GHz for RF frequency and support up to 18 GHz for the IF bandwidth. Also, the measured results show that the single-sideband conversion loss is less than 13. 7 dB over the available RF frequency band, while the minimum conversion loss is about 9 dB at an RF of 92. 5 GHz and an 1F of 3 GHz. Thus, a large operating bandwidth performance at W-band can be achieved by the orooosed mixer. 展开更多
关键词 BROAD-BAND W-BAND sub-harmonic mixer
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Investigation on the relationship between overpressure and sub-harmonic response from encapsulated microbubbles 被引量:2
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作者 吴军 范庭波 +1 位作者 许迪 章东 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第10期268-274,共7页
Sub-harmonic component generated from microbubbles is proven to be potentially used in noninvasive blood pressure measurement. Both theoretical and experimental studies are performed in the present work to investigate... Sub-harmonic component generated from microbubbles is proven to be potentially used in noninvasive blood pressure measurement. Both theoretical and experimental studies are performed in the present work to investigate the dependence of the sub-harmonic generation on the overpressure with different excitation pressure amplitudes and pulse lengths. With 4-MHz ultrasound excitation at an applied acoustic pressure amplitude of 0.24 MPa, the measured sub-harmonic amplitude exhibits a decreasing change as overpressure increases; while non-monotonic change is observed for the applied acoustic pressures of 0.36 MPa and 0.48 MPa, and the peak position in the curve of the sub-harmonic response versus the overpres- sure shifts toward higher overpressure as the excitation pressure amplitude increases. Furthermore, the exciting pulse with long duration could lead to a better sensitivity of the sub-harmonic response to overpressure. The measured results are ex- plained by the numerical simulations based on the Marmottant model. The numerical simulations qualitatively accord with the measured results. This work might provide a preliminary proof for the optimization of the noninvasive blood pressure measurement through using sub-harmonic generation from microbubbles. 展开更多
关键词 MICROBUBBLE OVERPRESSURE sub-harmonic response blood pressure measurement
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A Broadband 630-720 GHz Schottky Based Sub-Harmonic Mixer Using Intrinsic Resonances of Hammer-Head Filter 被引量:1
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作者 Yue He Yaoling Tian +2 位作者 Li Miao Jun Jiang XianJin Deng 《China Communications》 SCIE CSCD 2019年第2期76-84,共9页
An room temperature low noise anti-parallel Schottky diode based 630-720 GHz sub-harmonic mixer(SHM) is designed, built and measured. Intrinsic resonances in lowpass hammer-head filter have been adopted to prevent the... An room temperature low noise anti-parallel Schottky diode based 630-720 GHz sub-harmonic mixer(SHM) is designed, built and measured. Intrinsic resonances in lowpass hammer-head filter have been adopted to prevent the LO and RF power leak from the IF channel, while greatly minimizing the transmission line size. The mixer consists of 15 um quartz terahertz circuit and 127 um Al2 O3 IF transformer circuit. An improved lumped element equivalent noise model of SBDs guarantees the accuracy of simulation. The measurement indicates that with local oscillating(LO)signal of 2-8 mW, the lowest double sideband(DSB) conversion loss is 8.2 dB at 645 GHz,and the best DSB noise temperature is 2800 K at 657 GHz. The 3 dB bandwidth of conversion loss is 75 GHz from 638 to 715 GHz. The work IF frequency band is above 20 GHz ranging from 1 to 20 GHz with-10 dB return loss. 展开更多
关键词 erahertz sub-harmonic MIXER hammer-head FILTER SCHOTTKY diode
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Analysis method of chaos and sub-harmonic resonance of nonlinear system without small parameters
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作者 刘延彬 陈予恕 曹庆杰 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2011年第1期1-10,共10页
The Melnikov method is important for detecting the presence of transverse homoclinic orbits and the occurrence of homoclinic bifurcations. Unfortunately, the traditional Melnikov methods strongly depend on small param... The Melnikov method is important for detecting the presence of transverse homoclinic orbits and the occurrence of homoclinic bifurcations. Unfortunately, the traditional Melnikov methods strongly depend on small parameters, which do not exist in most practical systems. Those methods are limited in dealing with the systems with strong nonlinearities. This paper presents a procedure to study the chaos and sub-harmonic resonance of strongly nonlinear practical systems by employing a homotopy method that is used to extend the Melnikov functions to the strongly nonlinear systems. Applied to a given example, the procedure shows the effectiveness via the comparison of the theoretical results and the numerical simulation. 展开更多
关键词 homotopy analysis Melnikov function CHAOS sub-harmonic resonance
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1/3 PURE SUB-HARMONIC SOLUTION AND FRACTAL CHARACTERISTIC OF TRANSIENT PROCESS FOR DUFFING'S EQUATION
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作者 徐玉秀 胡海岩 闻邦椿 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2006年第9期1171-1176,共6页
The 1/3 sub-harmonic solution for the Duffing's with damping equation was investigated by using the methods of harmonic balance and numerical integration. The assumed solution is introduced, and the domain of sub-har... The 1/3 sub-harmonic solution for the Duffing's with damping equation was investigated by using the methods of harmonic balance and numerical integration. The assumed solution is introduced, and the domain of sub-harmonic frequencies was found. The asymptotical stability of the subharmonic resonances and the sensitivity of the amplitude responses to the variation of damping coefficient were examined. Then, the subharmonic resonances were analyzed by using the techniques from the general fractal theory. The analysis indicates that the sensitive dimensions of the system time-field responses show sensitivity to the conditions of changed initial perturbation, changed damping coefficient or the amplitude of excitation, thus the sensitive dimension can clearly describe the characteristic of the transient process of the subharmonic resonances. 展开更多
关键词 Duffing's equation sub-harmonic transient process fractal characteristic sensitive dimension
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Sub-Harmonic Resonances of Periodic Parameter Excited Oscillators with Discontinuities
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作者 Jifeng Cui 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2015年第4期66-71,共6页
It is difficult to obtain analytic approximations of nonlinear problems such as parameter excited system with strong nonlinearity. An analytic approach based on the homotopy analysis method( HAM) is proposed to study ... It is difficult to obtain analytic approximations of nonlinear problems such as parameter excited system with strong nonlinearity. An analytic approach based on the homotopy analysis method( HAM) is proposed to study the sub-harmonic resonances of highly nonlinear parameter excited oscillating systems with absolute value terms. The non-smoothness of absolute value terms is handled by means of an iteration approach with Fourier expansion. Two typical examples are employed to illustrate the validity and flexibility of this approach. The square residuals of the homotopy-approximations of the two examples decrease to 10-6and 10-5,respectively. Thus,the HAM combining with other methods gives hope to solve complex singular oscillating systems analytically. 展开更多
关键词 periodic parameter excited oscillator sub-harmonic resonance HAM Fourier expansion
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Assessing the effects of site factors on the productivity of a feller buncher:a time and motion analysis
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作者 Ebru Bilici Abdullah E.Akay Dalia Abbas 《Journal of Forestry Research》 SCIE CAS CSCD 2019年第4期1471-1478,共8页
We evaluated,for the first time in Turkey,the productivity of a feller buncher during clear-cut operations of two Brutian pine stands located in Canakkale,northwestern Turkey with different diameter classes and terrai... We evaluated,for the first time in Turkey,the productivity of a feller buncher during clear-cut operations of two Brutian pine stands located in Canakkale,northwestern Turkey with different diameter classes and terrain conditions.In the first stand with 24.6 cm average DBH,the feller buncher cut full trees and moved them to roadside.In the second stand with 34.3 cm average DBH,the feller buncher cut trees in two stages due to their larger diameters and the relatively steep and rough terrain conditions of the site.The effects of specific stand features,DBH and tree height measurements were assessed through statistical analysis in relation to productivity.The results indicate that the average productivity for the first stand was about 118 m^3h^-1,while it was about 80 m3h-1 in the second stand.Even though tree diameter and volume were higher in the second stand,productivity decreased by32.3%due to extra time spent on the two-stage cutting operation.The results revealed that harvesting operations should be planned carefully and the right equipment selected by accounting for different tree sizes,terrain conditions and machine specifications in order to better understand their effects on production. 展开更多
关键词 Timber HARVESTING FELLER buncher Timber size PRODUCTIVITY TIME and motion study
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无级变速器锥盘车磨复合加工数控技术探析
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作者 高晓翔 《黑龙江科学》 2023年第12期128-131,共4页
在无级变速器中,锥盘是重要部件,而数控车磨复合加工中心是锥盘生产的关键设备。从无级变速器锥盘复合加工关键技术分析入手,提出基于无级变速器的锥盘复合加工数控系统的构建,以提高锥盘精度及质量。
关键词 无级变速器 锥盘 复合加工 数控技术
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Radio Frequency Quadrupole for Bunching Electron Beam: Electromagnetic Field, Particle Velocity Range, and Accuracy at 10 GHz
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作者 Serigne Bira Gueye 《Journal of Electromagnetic Analysis and Applications》 CAS 2023年第1期1-11,共11页
The Radio Frequency Quadrupole (RFQ) accelerator invented by Kapchinskii and Tepliakov can focus, bunch, and accelerate charged-particle beams simultaneously. Typically, it operates at frequencies up to 500 MHz, for l... The Radio Frequency Quadrupole (RFQ) accelerator invented by Kapchinskii and Tepliakov can focus, bunch, and accelerate charged-particle beams simultaneously. Typically, it operates at frequencies up to 500 MHz, for low particle velocities ( β ). The first attempt to design cylindrical RFQ for electrons in the GHz region was done using 3 GHz at Frascati in 1990. In this paper, an analytical approximation of the electromagnetic field is given, and linearized in the beam region for a rectangular Electron Radio Frequency Quadrupole (ERFQ). The differences between the proton-RFQ and the electron-RFQ are discussed. Then, it will be shown that contrary to the quadrupoles for protons or heavy-ions, the ERFQ is suited for electron velocities in the range 0.5 - 0.7 c, and possible applications are given. Finally, it is illustrated, with numerical field computations that this approach gives sufficient accuracy at 10 GHz. 展开更多
关键词 Electron RF Quadrupole buncher Linear Accelerator LINAC Beam Injector
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A 220 GHz Frequency-Division Multiplexing Wireless Link with High Data Rate
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作者 ZHANG Bo WANG Yihui +2 位作者 FENG Yinian YANG Yonghui PENG Lin 《ZTE Communications》 2023年第3期63-69,共7页
With the development of wireless communication,the 6G mobile communication technology has received wide attention.As one of the key technologies of 6G,terahertz(THz)communication technology has the characteristics of ... With the development of wireless communication,the 6G mobile communication technology has received wide attention.As one of the key technologies of 6G,terahertz(THz)communication technology has the characteristics of ultra-high bandwidth,high security and low environmental noise.In this paper,a THz duplexer with a half-wavelength coupling structure and a sub-harmonic mixer operating at 216 GHz and 204 GHz are designed and measured.Based on these key devices,a 220 GHz frequency-division multiplexing communication system is proposed,with a real-time data rate of 10.4 Gbit/s for one channel and a transmission distance of 15 m.The measured constellation diagram of two receivers is clearly visible,the signal-to-noise ratio(SNR)is higher than 22 dB,and the bit error ratio(BER)is less than 10^(−8).Furthermore,the high definition(HD)4K video can also be transmitted in real time without stutter. 展开更多
关键词 frequency-division multiplexing sub-harmonic mixer terahertz communication terahertz duplexer
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Study of multipacting effect in sub-harmonic buncher of SSRF linac
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作者 张猛 赵明华 汪宝亮 《Chinese Physics C》 SCIE CAS CSCD 2009年第S2期86-88,共3页
During the design process, multipacting effect has been taken into consideration using a 2D simulation code MultiPac and all of the corners are rounded to suppress the multipacting effect in the pill-box cavity. Howev... During the design process, multipacting effect has been taken into consideration using a 2D simulation code MultiPac and all of the corners are rounded to suppress the multipacting effect in the pill-box cavity. However, unexpected multipacting effect prevents the increase of the input power when the magnetic field of focusing coils is added after adequate conditioning and a novel method is adopted to suppress it by introducing extra coils to counteract the field. This paper focuses on the simulation of multipacting effect in different magnetic field configurations. The experimental observations and simulation results of multipacting effect are presented and details of the multipacting process are also analyzed. 展开更多
关键词 sub-harmonic buncher multipacting effect 3D simulation coil compensation method
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FPGA实现次谐波聚束器的幅相控制 被引量:7
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作者 张俊强 殷重先 +3 位作者 高永强 俞路阳 赵明华 钟少鹏 《核技术》 CAS CSCD 北大核心 2012年第7期499-502,共4页
为满足上海光源Top-up运行模式的需要,保证光源直线加速器提供稳定的、高品质的束流,研制了次谐波聚束器的低电平控制系统。以可编程逻辑门阵列(FPGA)为基础,利用上下变频、IQ调制解调技术实现了次谐波聚束器幅度和相位的反馈控制。介... 为满足上海光源Top-up运行模式的需要,保证光源直线加速器提供稳定的、高品质的束流,研制了次谐波聚束器的低电平控制系统。以可编程逻辑门阵列(FPGA)为基础,利用上下变频、IQ调制解调技术实现了次谐波聚束器幅度和相位的反馈控制。介绍了数字化技术的原理及上层应用程序的开发,并进行桌面测试,实现了幅度控制精度1%、相位控制精度1的技术指标。 展开更多
关键词 FPGA低电平 次谐波聚束器 幅相控制
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HIRFL新B1聚束器的腔体设计 被引量:5
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作者 李智慧 周学厚 唐靖宇 《强激光与粒子束》 EI CAS CSCD 北大核心 1999年第6期771-775,共5页
根据HIRFL加速器的束流纵向匹配要求及实际情况,给出了新B1聚束器腔体的具体设计方案。采用短路片和两个移动电容板双调谐方式以满足该聚束器的宽工作频率范围要求。利用MAFIA程序对腔体的频率范围、品质因素Q值、损耗功... 根据HIRFL加速器的束流纵向匹配要求及实际情况,给出了新B1聚束器腔体的具体设计方案。采用短路片和两个移动电容板双调谐方式以满足该聚束器的宽工作频率范围要求。利用MAFIA程序对腔体的频率范围、品质因素Q值、损耗功率、微调电容及表面电流分布进行了计算,并就计算中可能引起的误差及方案的可行性进行了讨论。 展开更多
关键词 聚束器 腔体设计 HIRFL 重离子加速器
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HIRFL新B1聚束器耦合环的设计与计算 被引量:7
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作者 李智慧 唐靖宇 《强激光与粒子束》 EI CAS CSCD 北大核心 2000年第1期107-110,共4页
通过将聚束器腔体等效为 RLC并联回路 ,求得了功率馈入耦合环与腔体的互感及自感的公式 ,根据对腔体的计算结果求出了在聚束器的工作频段内达到阻抗匹配所要求的互感变化范围 ,并在该互感变化范围内设计了可移动的耦合电感环 ,计算了它... 通过将聚束器腔体等效为 RLC并联回路 ,求得了功率馈入耦合环与腔体的互感及自感的公式 ,根据对腔体的计算结果求出了在聚束器的工作频段内达到阻抗匹配所要求的互感变化范围 ,并在该互感变化范围内设计了可移动的耦合电感环 ,计算了它的自感及整个腔体的剩余电感。 展开更多
关键词 聚束器腔体 耦合电感环 HIRFL 粒子加速器
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上海光源次谐波聚束器的优化设计及测试 被引量:2
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作者 汪宝亮 赵明华 +1 位作者 侯汨 裴士伦 《强激光与粒子束》 EI CAS CSCD 北大核心 2008年第6期1053-1056,共4页
介绍了上海光源直线加速器499.654MHz次谐波聚束器的物理设计、结构、加工、微波测量和试验、运行等的情况。通过2维、3维电磁软件的数值模拟方法对腔型、结构尺寸、电磁参数、调谐范围进行了优化设计,现该腔已经加工完成,并对其进行了... 介绍了上海光源直线加速器499.654MHz次谐波聚束器的物理设计、结构、加工、微波测量和试验、运行等的情况。通过2维、3维电磁软件的数值模拟方法对腔型、结构尺寸、电磁参数、调谐范围进行了优化设计,现该腔已经加工完成,并对其进行了电参数测试,结果与物理设计指标吻合很好。在上海光源的束流指标调试过程中,该腔能长期稳定运行。 展开更多
关键词 次谐波聚束器 优化设计 微波测量 带束功率实验
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HIRFL中的束流纵向运动 被引量:7
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作者 唐靖宇 尹全民 《强激光与粒子束》 EI CAS CSCD 北大核心 1999年第6期765-770,共6页
对兰州重离子加速器的两台等时性回旋加速器中的束流纵向运动作了简单分析,主要介绍两条束运线上的几台聚束器的物理设计。超低能束运线-SFC轴向注入线上的两台聚束器采用了线性聚束器,并提出了用半频聚束来提高两台回旋加速器的... 对兰州重离子加速器的两台等时性回旋加速器中的束流纵向运动作了简单分析,主要介绍两条束运线上的几台聚束器的物理设计。超低能束运线-SFC轴向注入线上的两台聚束器采用了线性聚束器,并提出了用半频聚束来提高两台回旋加速器的纵向匹配效率的新方法。低能束运线(BL1)上的聚束器采用多工作模式以解决加速粒子和能量范围宽的问题。 展开更多
关键词 束流纵向运动 聚束器 HIRFL 重离子加速器
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142.8MHz次谐波聚束腔的结构优化设计 被引量:5
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作者 裴士伦 王书鸿 +1 位作者 顾鹏达 耿哲峤 《强激光与粒子束》 EI CAS CSCD 北大核心 2004年第6期795-799,共5页
使用二维有限差分法分析软件Superfish和三维有限积分法分析软件MAFIA ,对 14 2 .8MHz次谐波聚束腔的结构进行了模拟和优化研究 ,给出了聚束腔结构优化设计的步骤和方法 ,确定了优化后聚束腔的基本结构。分析比较了Superfish和MAFIA两... 使用二维有限差分法分析软件Superfish和三维有限积分法分析软件MAFIA ,对 14 2 .8MHz次谐波聚束腔的结构进行了模拟和优化研究 ,给出了聚束腔结构优化设计的步骤和方法 ,确定了优化后聚束腔的基本结构。分析比较了Superfish和MAFIA两个软件的模拟优化结果 ,得出了基本一致的结论。还探讨了Su 展开更多
关键词 束流动力学 次谐波聚束腔 Superfish MAFIA 有限差分法 有限积分法
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单漂移聚束器的非标准聚束模式 被引量:3
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作者 张焱 关遐令 《原子能科学技术》 EI CAS CSCD 北大核心 1993年第1期1-8,共8页
单漂移聚束器标准聚束模式要求粒子注入能量和聚束器漂移管的几何尺寸之间必须满足严格的条件,严重地限制了可聚束粒子的种类。文章论述了采用非标准聚束模式的方法,计算不同粒子在HI-13串列加速器上实现脉冲聚束的可行性。
关键词 单漂移 聚束器 非标准聚束 粒子束
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次谐波聚束器相位控制的算法改进 被引量:2
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作者 张俊强 俞路阳 +2 位作者 殷重先 赵明华 钟少鹏 《强激光与粒子束》 EI CAS CSCD 北大核心 2011年第8期2179-2182,共4页
为实现次谐波聚束器的数字化相位控制,利用下变频、IQ调制解调技术及商业化的PXI系统,开发了以LabVIEW为平台的低电平控制器。控制器采用了具有自学习和自适应能力的单神经元自适应PID的控制算法,满足了相位稳定度的要求,通过现场测试... 为实现次谐波聚束器的数字化相位控制,利用下变频、IQ调制解调技术及商业化的PXI系统,开发了以LabVIEW为平台的低电平控制器。控制器采用了具有自学习和自适应能力的单神经元自适应PID的控制算法,满足了相位稳定度的要求,通过现场测试与传统PID算法进行比较,验证了该算法稳定性好、响应快、抗干扰能力强。 展开更多
关键词 次谐波聚束器 相位控制 单神经元 PID控制
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9MeV行波电子直线加速器加速管的物理设计 被引量:6
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作者 陈怀璧 丁晓东 林郁正 《原子能科学技术》 EI CAS CSCD 北大核心 2000年第1期20-26,共7页
海关大型货物在线检测用加速器采用4MW速调管作为微波功率源,保证加速管入口功率可达35MW、工作频率为2856MHz;以行波方式加速电子,聚束器俘获效率大于80%;加速管全长约220cm;电子能量设置9、6MeV两档,对应的额定脉冲束流强度理论设计... 海关大型货物在线检测用加速器采用4MW速调管作为微波功率源,保证加速管入口功率可达35MW、工作频率为2856MHz;以行波方式加速电子,聚束器俘获效率大于80%;加速管全长约220cm;电子能量设置9、6MeV两档,对应的额定脉冲束流强度理论设计值分别为170和300mA。本文给出了纵向粒子动力学。 展开更多
关键词 行波电子直线加速器 加速管 物理设计
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