超声波作用下声学参数对悬浮液中微粒凝聚的影响

对利用超声波去除或分离悬液中微小颗粒过程中频率和时均声能密度等声学参数对微粒凝聚的影响作了分析研究。利用前人的数学模型对不同声对比因数下悬浮液中微粒达到平衡状态时所需要的时间及凝聚位置进行了计算。在水模型实验,实验中所施加超声波的频率为24.1kHz,微粒的粒径为0-60um、密度940kg/m^3的高密度聚乙烯,实验液为脱气软化水,实验结果与部分理论分析结果是一致的。     

直流清洗电场对储存环聚焦参数修正作用的研究

研究了直流清洗电场对储存环聚焦参数的修正作用.认为该清洗电场形成的横向振荡数移位,与储存束流闭轨实时位置有关.指出电极沿环不对称分布的此类清洗电场,会破坏储存环聚焦结构的对称性,降低储存环的接受度,在一定条件下,对注入积累束流过程有负作用.     

逐圈测量系统在合肥光源数字反馈调试中的应用

 使用逐圈测量系统作为观测手段,通过对逐圈测量系统采集所得数据进行分析,判断了数字反馈系统调试过程中的反馈效果。在改变六极铁电流以逐步改变储存环的色品值的过程中,通过逐圈测量系统观察了束流不稳定性,计算得到振荡增长时间和阻尼时间分别为0.258 ms和1.172 ms。并测量和计算了工作点、相空间等束流特性参数,分析了束流靠近和穿越5/9共振线的完整过程。     

Classical and modern power spectrum estimation for tune measurement in CSNS RCS

Precise measurement of betatron tune is required for good operating condition of CSNS RCS. The fractional part of betatron tune is important and it can be measured by analyzing the signals of beam position from the appointed BPM. Usually these signals are contaminated during the acquisition process, therefore several power spectrum methods are used to improve the frequency resolution. In this article classical and modern power spectrum methods are used. In order to compare their performance, the results of simulation data and IQT data from J-PARC RCS are discussed, It is shown that modern power spectrum estimation has better performance than the classical ones, though the calculation is more complex.     

Stabilization of betatron tune in Indus-2 storage ring

Indus-2 is a synchrotron radiation source that is operational at RRCAT, Indore, India. It is essentially pertinent in any synchrotron radiation facility to store the electron beam without beam loss. During the day to day operation of Indus-2 storage ring, difficulty was being faced in accumulating higher beam current. After examination, it was found that the working point was shifting from its desired value during accumulation. For smooth beam accumulation, a fixed desired tune in both horizontal and vertical plane plays a significant role in avoiding beam loss via the resonance process. This required a betatron tune feedback system to be put in the storage ring. After putting ON this feedback, the beam accumulation was smooth. The details of this feedback and its working principle are described in this paper.     

Double quasi phase matching for both optical parametric oscillator and difference frequency generation

We present simultaneous phase matching of optical parametric oscillator (OPO) and difference frequency generation (DFG), using a noncollinear interaction in periodically poled crystal with single grating. Selecting proper grating period Λ and titled angle ξ between the grating vector G and the optical axis of crystal, the noncollinear scheme provides double phase matching solutions over continuous regions of the midwave infrared spectrum. At certain wavelength regions, for DFG process the group velocities between interaction pulses are matching and the phase matching bandwidth reaches maximum. Selecting the different grating period, the broadband midwave tuning and better gain spectrum can be obtained at different wavelength range. For the certain period grating the conversion efficiency is higher. Hence, using the double phase matching configuration, the broadband tunable midwave infrared wave can be produced in single grating. But the configurations have a relatively narrow angular bandwidth.     

HLS-Ⅱ储存环工作点测量系统的开发（英）

介绍了在合肥光源重大维修改造工程期间,开发的一套基于扫频激励法的工作点测量系统。测量系统硬件包括基于条带BPM的信号拾取电极、前端信号调理模块、一台带跟踪输出的信号分析仪N9000AEP、功率放大器以及用于激励束流的条带激励器。系统控制软件采用EPICS开发,基于EPICS Stream Device设计的输入输出控制器(soft IOC)运行在服务器虚拟机中,通过VXI11协议进行通信实现对信号分析仪的控制和数据获取;用户操作界面采用EPICS平台下的EDM开发,通过Channel Access与IOC通信。在HLS-II储存环上对工作点测量系统进行了在线的调试。调试结果说明,在扫频范围为2.1 MHz到4.1 MHz时,工作点测量系统的统计分辨率在水平方向上好于0.000 3,在垂直方向上好于0.000 2。     

VHF波段超窄带超导滤波器的设计及其时域调谐

低频超窄带滤波器要求谐振器间的耦合极弱,设计受到薄膜面积限制,其性能对基片介电常数的均匀性极为敏感且受制作和封装精度的限制.这些因素将导致的滤波器中心频率偏移和带内性能恶化.对此,时域调谐提供了很好的解决途径.我们采用嵌套双螺旋型谐振器,在37mm×12mm的MgO基片上设计制作了4节超导滤波器,中心频率为166.9 MHz,相对带宽仅为0.29%.由于基片厚度或介电常数的偏差及不均匀性会导致滤波器中各谐振的谐振频率偏移,使通带性能受到很大影响.我们提出了将机械调谐与时域分析相结合的方法,通过机械调谐纠正各谐振器的谐振频率,改善滤波器性能.同时为了解决多信道滤波器系统中,各滤波器工作于同一温度下,系统频率一致性问题,通过时域调谐获得频率可调范围信息.对上述0.5 MHz带宽的VHF波段滤波器应用时域调谐方法,得到的可调范围为0.7 MHz,测试结果表明该滤波器具有优异性能,带内插损小于0.4 dB,反射损耗达到14.8 dB,带外抑制大于-70 dB.     

Tune optimization of the third generation light source storage ring based on Frequency Map Analysis

Tune optimization is necessary to optimize the nonlinearity of the third generation light source storage ring. In this paper we summarize the common strategies for choosing a tune and discuss tune op- timization. Frequency Map Analysis （FMA） is applied as a tune scanning tool to reveal information about nonlinear resonances and guide the tune optimization. The Shanghai Synchrotron Radiation Facility （SSRF） storage ring is taken as a test lattice, and the optimum solutions are presented in this paper. Moreover, the third order regular structural resonances excited by sextupoles are particularly investigated, and it is found that these resonances distort the tune shifts with amplitude and show a stop-band like the linear structural resonances.     

HLS逐束团跟踪监测系统

介绍了合肥光源(HLS)逐束团跟踪监测系统, 并且展示了相关的实验、数据分析 结果. 通过同相的门电路信号和RF的分频信号控制ADC的外触发, 对该测量系统的可靠性、稳定性进行了验证. 并且利用该系统, 跟踪记录了完整的注入, 慢加速, 降频, 校正轨道, 扭摆磁铁充电, 加斜四极铁以及正常供光运行的全过程. 最后展示了该过程的横向工作点(tune值)漂移, 多束团耦合不稳定性的研究结果.