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刘建飞 《南昌大学学报(理科版)》2007,31(6):566-569
研究了不同的表面改性剂对超细氢氧化镁的表面改性.并分别以水和乙醇为溶剂,研究了表面改性后氢氧化镁的分散行为.实验结果表明,以水为溶剂的体系,六偏磷酸钠分散性能最好,而以乙醇为溶剂,硅烷偶联剂KH-550分散性能最好,其用量为基体量的5%左右,可使制备的超细氢氧化镁粒径达到0.2 μm尺度以下.试验结果对进一步认识超细氢氧化镁的性质及其应用具有重要意义. 相似文献
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Epichlorohydrin (ECH) was polymerized with a rare earth catalytic system: Nd (i-OPr)_3-Al (i-Bu)_3. The effects of Al/Nd molar ratio, solvents, the polymerization time and temperature,the aging time and temperature of the catalyst preparation were studied. The results showed thatat a low Al/Nd molar ratio (4) of the Nd(i-OPr)_3-Al(i-Bu)_3 system ECH polymerized at a lowtemperature (248K) with a high conversion. The average molecular weight ofpolyepichlorohydrin (PECH) ranged from 1×10~5 to 3×10~5. 相似文献
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离子色谱作为一种新型高效液相色谱技术, 最初主要应用于测定样品中的阴阳离子含量, 如今发展为应用于有机酸、生物胺、糖类等化合物的组成及含量测定. 离子色谱法具有操作简便、灵敏度高以及选择性好等优点, 因此, 目前离子色谱法已在能源、环境、地质、食品、药物等领域得到了广泛应用. 总结了近年来离子色谱在中药金属离子、无机阴离子、有机酸、糖类成分的研究进展, 为离子色谱法分析中药化学成分提供了参考. 相似文献
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Quench is important and dangerous to superconducting RF cavities. This paper illustrates the mechanism of quench and how a quench detector works, and analyzes the quench events happening during beam operations and cavity conditioning. We find that the quench protection is mostly triggered by some reasons such as fluctuation of cavity voltage, multipacting or arc, rather than a real cavity thermal breakdown. The results will be beneficial to optimize the operation parameters of superconducting cavities, to discover the real reasons for beam trip by quench interlock, and to improve the operation stability of superconducting RF systems. 相似文献
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Higher harmonic cavity used in the third generation synchrotron light source increases the Touschek lifetime. The higher harmonic cavity of Shanghai Synchrotron Radiation Facility (SSRF) is a 1.5GHz passive superconducting cavity. Its higher order modes (HOM) are extracted by a ferrite HOM damper out of the cryostat. Multi-cell cavity is chosen concerning the voltage. The harmonic cavity dynamics, beam dynamics with passive harmonic cavity and the design of single cell cavity are included in this paper. 相似文献
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Digital prototype of LLRF system for SSRF 总被引:2,自引:0,他引:2
This paper describes a field programming gate array (FPGA) based low level radio frequency (LLRF) prototype for the SSRF storage ring RF system. This prototype includes the local oscillator (LO), analog front end, digital front end, RF out, clock distributing, digital signal processing and communication functions. All feedback algorithms are performed in FPGA. The long term of the test prototype with high power shows that the variations of the RF amplitude and the phase in the accelerating cavity are less than 1% and 1° respectively, and the variation of the cavity resonance frequency is controlled within ±10 Hz. 相似文献
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A third harmonic superconducting niobium cavity has been proposed for installation in the Shanghai Synchrotron Radiation Facility (SSRF) storage ring to improve the Touschek lifetime. In order to investigate the feasibility of the superconducting cavity fabrication indigenously and the possibility to master the fabrica tion techniques, cavities were fabricated from copper and niobium sheets by deep drawing and electron-beam welding, and a series of measurements, such as resonant frequency, shape dimensions and wall thickness, were carried out during this process. After analysis of various problems existing in the fabrication process, technique improvements were proposed, and finally the precise shape as designed and resonant frequency within 1.2 MHz were achieved for the new completed cavities. In addition, full annealing was finally proved to be a good cure for niobium sheets' tearing up during deep drawing. By fabricating niobium cavities successfully, some problems to the next step were cleared. This paper introduces the process of cavity fabrication and its technique improvements towards forming, and the initial vertical test result of niobium cavity is also presented. 相似文献
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