Fluorescence lifetime measurement from a designated single-bunch in the BEPCⅡ colliding mode

Fluorescence lifetime measurement in the time domain requires excitation from a well separated single bunch using synchrotron light sources. In the colliding mode of the Beijing Electron Positron Collider Ⅱ (BEPCⅡ), a hybrid filling pattern was realized such that a single bunch was placed in the middle of a large gap between two multi-bunch groups. Detection of fluorescence lifetime, based on the excitation of the light pulse from this designated single-bunch, was established at Beamline 4B8 of the Beijing Synchrotron Radiation Facility (BSRF). The timing signal of the BEPCII was utilized as a trigger to gate this fluorescence event. L-Tryptophan amino acid, a known lifetime standard, was selected to assess the lifetime measurement performance. The measured lifetime was consistent in both colliding and single-bunch mode with the time resolution down to 450 ps. Moreover, both the bunch purity and the fine structure of the hybrid filling pattern were characterized.     

基于磁流变弹性体-压电片混合梁结构的宽频振动能量回收装置（英文）

振动能量回收装置能够将环境动能转化为电能,然而其工作频率范围窄、产生的功率小是这个领域的突出问题.为了增加其工作频率范围,科研工作者已经开发研究了许多技术方案,例如采用多种振动模式、谐振调谐和非线性技术来拓宽其有效频率范围.本文提出了一种新型混合非线性振动能量回收装置,主要包括磁流变弹性体(MRE)层、压电片和末端质量.新提出的能量回收装置利用MRE的刚度可控特性来开发非线性能量回收装置.多层MRE压电梁结构由永磁体包围,以在MRE梁周围形成封闭磁场,从而产生非线性刚度.柔性磁流变弹性体-压电混合梁的高度柔韧性使得其与等厚度的铝基能量回收装置相比具有更大的振幅,从而收集更多的能量.同时,对这一新型能量回收装置进行了实验和理论研究以分析其综合性能,包括其有效工作频率范围和发电功率.此外,作为比较,测试了一种线性能量采集器的各项性能.线性能量采集器与混合能量采集器之间的比较表明,本文所提出的混合非线性能量采集器具有更宽的有效频率范围,并且能够回收更多的能量.