基于PC的光学速调管磁间隙控制系统

描述了合肥国家同步辐射实验室(NSRL)储存环自由电子激光(SRFEL)光学速调管(TOK)磁极间隙控制系统的原理和结构，给出了系统硬件结构、软件流程图及其工程实现。该调节系统可以独立或同时调节TOK调制段、色散段、辐射段三部分磁极间隙的大小，精度达到0.01mm；多重安全保护能确保储存环真空室不被破坏。     

用于自由电子激光装置的丝扫描束流横向截面测量系统原型机

基于丝扫描系统的束流横向截面测量为半阻拦式的测量方法,相比于截面靶测量对束流影响较小。上海高重复频率硬X射线自由电子激光装置(SHINE)束团截面在线测量系统计划采用丝扫描技术实现,为此设计研制了由丝靶探头、机械运动机构、束损探测器、电子学系统构成的丝扫描束流横向截面测量系统原型机。本文介绍了该原型机的工作原理、具体设计及在丝扫描探头上游安装腔式束流位置测量(CBPM)系统进行束流中心位置和束团电荷量精确补偿的优化方案。为精确评估该样机系统性能,在上海软X射线自由电子激光(SXFEL)中相邻位置布局了丝扫描探头和YAG靶截面探头,通过同时测量并对比同样束流截面的方法,对丝扫描系统原型机性能进行了束流实验评估。束流实验结果表明,在束团电荷量500 pC、电子能量0.84 GeV的条件下,丝扫描技术可用于电子束团的在线半阻拦式截面测量,测量不确定度好于30μm,测量结果与SXFEL装置标配的YAG靶截面靶测量系统结果一致。     

基于PC的光学速调管色散段磁极间隙调节系统

描述了合肥国家同步辐射实验室（ＮＳＲＬ）光学速调管色散段磁极间隙调节系统的原理和结构。该调节系统已应用在ＮＳＲＬ的储存环自由电子激光实验中,效果良好,调节精度可高达１０－３ｍｍ。     

面形误差对自由电子激光聚焦光斑影响的研究

正在建设中的上海软X射线自由电子激光(Self-amplified Spontaneous Emission,SASE)光束线—活细胞成像光束线,能量范围100～1 000 eV,束线主要设备包括前端区、插入件、偏转平面镜PM1、诊断光栅PM2、单色器、压弯镜、KB镜(Kirkpatrick-Baez)和椭球镜等。分为两条支线,其中北支线的KB镜组由一个平面镜和两个椭圆柱面镜构成,主要应用于生物细胞成像实验站。实际光学元件在加工过程中会存在一定的面形误差,面形误差是衡量光学元件表面质量的重要指标。自由电子激光光束线系统中,要求镜子表面具有高精度和高可靠度,镜子的面形和高度误差相关联,会影响光束的相干性和波前,进而影响最终的光斑。为了准确研究面形误差对X光经过光束线传播后相干性和波前变化的影响,使用软件SHADOW和SRW对北支线X光的传播进行模拟。模拟结果表明:平面镜面形误差控制在0.1～0.2μrad,同时椭圆柱面镜控制在0.4μrad以内,聚焦光斑尺寸在4μm以内,可满足生物成像实验站成像需求。该结果为软X射线自由电子激光的优化设计提供了参考和依据。     

毛细管放电泵浦软X射线激光装置

脉冲功率技术在激光领域中得到广泛的应用,根据毛细管放电泵浦软X射线激光的机理及据此要求设计了高压大电流快脉冲放电泵浦软X射线激光装置。该装置由Marx发生器、Blumlein脉冲形成线及毛细管负载组成。Marx发生器由10级电容器组成。每级电容器由2台0.047μF、30kV油介质电容器并联。Marx发生器串联电容CM=9.4nF。采用正负充电方式,5个火花隙开关,开关的导通均由外触发。整个Marx发生器固定在绝缘支架上,并装入充以氮气的钢筒内。Blumlein线阻抗采取等阻抗形式,Z1=Z2=5Ω;输出阻抗ZB=Z1 Z2=10Ω;输出脉冲半高宽τ=35ns。Blumlein线的绝缘介质为去离子水。电阻率ρ≈1～2MΩ·cm,相对介电常数ετ=80。Blumlein线等效电容CB=C1 C2=7.3nF。     

基于PC的光学速管色散段磁极间隙调节系统

描述了合肥国家同步辐射实验室光学速调管色散段磁极间隙调节系统的原理和结构。该调节系统已 ＮＳＲＬ的储存环自由电子激光实验中,效果良好,调节精度可高达１０＾－３ｍｍ。     

上海软X射线自由电子激光腔式束流位置测量系统

上海软X射线自由电子激光装置（Shanghai Soft X-ray Free Electron Laser, SXFEL）需1个分辨率达到亚μm量级的束流位置测量系统,并采用基于束流准直的方法实现波荡器段电子束与光子束的紧密重合。为此设计研制了1个由C波段腔式探头、单路混频至低中频的射频前端以及自主研发的专用数字信号束流位置处理器（digital beam position monitor processor, DBPM）构成的腔式束流位置测量（cavity beam position monitor, CBPM）系统。本文对系统的设计、软硬件结构、系统搭建进行了介绍,并基于漂移段搭建的3个紧邻的CBPM阵列完成了在线系统性能评估。束流实验结果表明,在束团电荷量为500 pC、系统动态范围在±800 μm的条件下,位置分辨率可达880 nm,这也是国内首次研制成功可在线运行的具有亚μm位置分辨率的CBPM系统。此外,采用CBPM的相位腔进行相对束团电荷量、束团到达时间的测量,其性能评估结果也均优于SXFEL设计要求。     

8.0nnX射线激光反射镜Mo／B4C多层膜制备及其特性

用磁控溅射法制备工作波长约８．０ｎｍ的Ｍｏ／Ｂ４Ｃ的多层膜作为正入射短波长（λ〈１０．０ｎｍ）软Ｘ射线激光反射腔的反射镜,经Ｘ射线衍射仪和ＴＥＭ检测,多层膜周期结构准确,热稳定性高。     

8.0 nm X射线激光反射镜Mo/B4C多层膜制备及其特性

The Mo/B₄C multilayer at wavelength of 8.0 nm is fabricated by magnetron sputtering. The microstructure of multilayer are tested using X-ray diffraction and TEM,and the results show that Mo/B₄C multilayer have high structural quality and thermal stability.     

Wakefields studies for the SXFEL user facility

Besides the original seeded undulator line,in the soft X-ray free-electron laser (SXFEL) user facility in Shanghai,a second undulator line based on self-amplified spontaneous emission is proposed to achieve 2-nm laser pulse with extremely high brightness.In this paper,the beam energy deviation induced by the undulator wakefields is numerically calculated,and 3D and 2D results agree well with each other.The beam energy loss along the undulator degrades the expected FEL output performances,i.e.,the pulse energy,radiation power and spectrum,which can be compensated with a proper taper in the undulator.Using the planned time-resolved diagnostic,a novel experiment is proposed to measure the SXFEL longitudinal wakefields.     

Beam test results of high Q CBPM prototype for SXFEL

In pursuit of high-precision beam position measurements at micrometers or submicrometers for the Shanghai soft X-ray free-electron laser (SXFEL) facility which is under construction in the vicinity of the Shanghai Synchrotron Radiation Facility,a high Q cavity beam position monitor (CBPM) with a resonant frequency of 4.7 GHz is developed by the Shanghai Institute of Applied Physics,and the relevant BPM electronics with a dedicated RF front end,and a digital BPM,are completed.The cavity design,cold test,system architecture,and first beam test are performed at the Shanghai deep ultraviolet free-electron laser (Zhao et al.in Nucl Instrum Meth A 528(1-2):591-594,2004.doi:10.1016/j.nima.2004.04.108) facility.Results of the beam experiment show that the performance of the CBPM is consistent with basic expectations,and the beam position resolution can fulfill the requirements for the SXFEL project if the beam conditions are optimized.     

GM计数管的线性化

本文给出一种适合于所有GM计数数线性化的电路及测试结果。文中给出适于几种GM计数管死时间τ和计数率n之间关系的表达式,因而提供一个通过微机使GM计数管线性化的方法。     

低能γ射线反散射法测量煤灰分的线性处理

理论计算表明,煤的灰分与低能γ射线反散射强度之间是一种非线性关系。数学分析和实验证明,在较窄的灰分范围内,灰分与反散射强度之间可按线性关系处理。本文结合实际的宽范围的标定曲线,讨论了非线性函数的线性化范围及线性化误差,并对不同的测量范围提供了电路设计的参考数据。     

Design and study of a C-band pulse compressor for the SXFEL linac

A C-band RF pulse compressor is in development at SINAP It comprises of two resonant cavities,two mode convertors and a 3 dB power divider.TE_(0.1.15)mode is selected for obtaining higher quality factor Q_0 of the RF pulse compressor cavities,so that the power gain factor can be 3.2,which is supposed to multiply the RF power from 50 MW to 1 60 MW.In this paper,we report our work on C-band RF pulse compressor,namely the design simulation and cold test results.     

Generation of double pulses at the Shanghai soft X-ray free electron laser facility

In this article,we present the promise of a new method generating double electron pulses in picosecondscale pulse length and tunable interpulse spacing at several picoseconds.This has witnessed an impressive potential of application in pump-probe techniques,two-color X-ray free electron laser,high-gradient witness bunch acceleration in a plasma,etc.Three-dimensional simulations are carried out to analyze the dynamic of the electron beam in a linear accelerator.Comparisons are made between the new method and existing ways.     

Generation of double pulses at the Shanghai soft X-ray free electron laser facility

In this article, we present the promise of a new method generating double electron pulses in picosecondscale pulse length and tunable interpulse spacing at several picoseconds. This has witnessed an impressive potential of application in pump–probe techniques, two-color X-ray free electron laser, high-gradient witness bunch acceleration in a plasma, etc. Three-dimensional simulations are carried out to analyze the dynamic of the electron beam in a linear accelerator. Comparisons are made between the new method and existing ways.     

速调管走廊泄漏电磁噪声的模拟计算与对比测试

为确定泄漏噪声源的特性及位置,对国家同步辐射实验室速调管走廓泄漏电磁噪声进行了模拟计算,给出了调制器高频泄漏噪声的计算方法和计算公式。在模拟计算的基础上进行了现场的对比测试,对比测试结果显示了模拟计算的合理性,从而为抑制走廓的噪声泄漏提供了理论基础。     

NSRL 200MeV电子直线加速器的速调管真空保护装置

报道了一种能保护高功能速调管安全的速调管真空保护装置。该装置保护动作时间≤１５ｍｓ，在强电磁干扰速调管走廓中能稳定可靠地工作。