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选择了一台商业化的前端电子学RFTF(radio frequency front-end for transverse feedback system)用于BEPCII横向束流反馈系统, 这是跟进世界先进加速器技术的具体实施。在BEPC同步运行模式下对RFTF的性能进行了测试实验,结果表明使用RFTF可以得到理想的波形,能够满足BEPCII横向反馈系统的需要,但是,当储存环出现不稳性时,系统无法正常工作,这就要求BEPCII纵向不稳定很小或者用纵向反馈系统来抑制存在的纵向不稳定。 相似文献
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BEPCII是一个多束团、大流强的装置, 由于高频腔的高次模和电阻壁阻抗等因素,不可避免地会出现束流不稳定性。BEPCII中采用束流反馈系统来抑制束流不稳定性。横向束流反馈系统主要包括前端电子学、信号处理电子学、反馈器件和放大器等几个部分。梳状滤波器是信号处理电子学的重要部件,利用两根长短不同的电缆以及一个功分器和合成器构成了一种简单有效的梳状滤波器,其梳状深度达到-41 dB,使用这种梳状滤波器的横向反馈系统成功地抑制了束流中出现的不稳定性。 相似文献
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BEPCII是一个多束团、大流强的装置, 由于高频腔的高次模和电阻壁阻抗等因素,不可避免地会出现束流不稳定性。BEPCII中采用束流反馈系统来抑制束流不稳定性。横向束流反馈系统主要包括前端电子学、信号处理电子学、反馈器件和放大器等几个部分。梳状滤波器是信号处理电子学的重要部件,利用两根长短不同的电缆以及一个功分器和合成器构成了一种简单有效的梳状滤波器,其梳状深度达到-41 dB,使用这种梳状滤波器的横向反馈系统成功地抑制了束流中出现的不稳定性。 相似文献
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为了提高注入束流的积累,抑制由于注入系统误差引起较大的β残余振荡是非常有必要的。较系统地介绍了利用合肥光源逐圈测量(turn by turn)系统[1],研究束流不稳定性,并给出了抑制注入β振荡的反馈系统设计原理和线路及初步实验结果。作为原理论证和预研,使用了一个相对简单的模拟滤波移相器对Kicker过程激发的β振荡进行反馈,得到了明显的对damping时间和振荡幅度的抑制作用,为以后低频和高频逐束团(bunch by bunch) 反馈系统研制和抑制束流的横向和纵向不稳定性的研究打下了良好的基础。 相似文献
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用高频结构模拟程序HFSS优化设计条带电极kicker并计算了它的反射参数和横向分流阻抗。从模拟得到的反射参数可以看出,在要求的250MHz带宽范围内, 反射的功率小于7%,说明了条带与功率传输线是阻抗匹配的;模拟得到的横向分流阻抗与公式计算得到的结果基本上一致。当频率250MHz时,得到了1 300Ω的分流阻抗,在此种条件下,需要反馈功率为123W方能抑制束流不稳定性,这为电极的机械设计和在反馈系统中选择功率放大器提供了最基本的依据。 相似文献
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A matrix formulation is presented, which enables us to study the propagation of axis-symmetric beams through a paraxial optical ABCD system containing hard-edged aperture. Numerical calculation results of super-Gaussian beams passing through a multi-aperture-lens system are given to illustrate the advantage of the method. A comparison of the matrix formulation, complex Gaussian expansion and direct numerical integration of the Collins formula is made, where the propagation of apertured Laguerre-Gaussian beams is chosen as an illustrative example. It is shown that the matrix formulation provides satisfactory results in both Fraunhofer and Fresnel regions, and reduces the computational time greatly in comparison with the direct integration. However, this method is suited only to axis-symmetric optical beams and systems. By using the complex Gaussian expansion discrepancies exist in the near zone closer to the aperture, but usually its computational efficiency is higher than the matrix formulation. 相似文献
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Zhangrong Mei 《Optics Communications》2011,284(22):5248-5252
The focal shifts of focused truncated random electromagnetic beams are investigated. Based on the complex Gaussian expansion method for a hard-edged aperture function, the analytical propagation formula of cross-spectral density matrix for a random electromagnetic beam focused by an optical system with a thin lens and a circular aperture is derived. The Fresnel numbers related with the beam and system parameters are defined and used to examine focal shifts. The dependence of the focal shifts on the different Fresnel numbers and polarization distribution are discussed in detail with numerical examples. 相似文献
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用原子力、Normaski和扫描电子显微镜等分析仪器,对高损伤阈值薄膜常采用的HfO2光损伤所形成的孔洞,与镀制过程中形成的孔洞形貌相似,激光再损伤能力也相似。低能量密度的激光把节瘤缺陷变为孔洞缺陷是激光预处理提高薄膜损伤阈值的原因之一。 相似文献
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By expanding the hard-aperture function into a finite sum of complex Gaussian functions, analytical formulae for the electric field of a general-type beam propagating through apertured aligned and misaligned ABCD optical systems are derived using the generalized Collins formulae, which provide a convenient way of studying the propagation of a variety of laser beams, such as Gaussian, cos-Gaussian, cosh-Gaussian, sine-Gaussian, sinh-Gaussian, flat-topped, Hermite-cosh-Gaussian, Hermite-sine-Gaussian, higher-order annular Gaussian, Hermite-sinh-Gaussian and Hermite-cos-Gaussian beams, through such optical systems. As numerical examples, the propagation properties of a cos-Gaussian beam through an apertured aligned or misaligned thin lens are studied. 相似文献
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Based on the generalized Huygens–Fresnel diffraction integral and the expansion of the hard aperture function into a finite sum of complex Gaussian functions, the approximate analytical expression of elegant Laguerre–Gaussian beams passing through a paraxial ABCD optical system with an annular aperture is derived. Meanwhile, the corresponding closed-forms for the unapertured, circular apertured or circular black screen cases are also given. The obtained results provide more convenience for studying their propagation and transformation than the usual way by using diffraction integral formula directly. Some numerical examples are given to illustrate the propagation properties of elegant Laguerre–Gaussian beams. 相似文献
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双曲余弦高斯光束通过有光阑限制的ABCD光学系统的传输 总被引:8,自引:0,他引:8
对双曲余弦高斯光束通过有硬边光阑的一阶ABCD光学系统的传输进行了研究,采用将矩形域函数表示为复高斯函数叠加的技巧,推导出了解析的传输公式,在特殊情况下,该公式简化为在无光阑情况下的传输公式,对双曲余弦高斯光束通过有光阑限制的薄膜镜聚焦进行了数值计算,计算结果与直接由柯林斯(Collins)公式所得结果一致,且此解析方法便于进行物理分析,可节约大量机时。 相似文献
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利用矢量瑞利衍射积分公式,推导出非傍轴矢量高斯光束圆屏衍射的解析表示式.非傍轴矢量高斯光束圆屏衍射的轴上场分布、远场表示式、自由空间中的传输公式,以及傍轴近似下高斯光束圆屏衍射的菲涅耳和夫琅禾费衍射公式可以作为一般公式的特例统一处理.数 值计算和比较实例说明了非傍轴矢量高斯光束的光强分布和远场特性.分析表明,在圆屏衍 射中,f参数和截断参数决定光束的非傍轴行为.
关键词:
传输光学
非傍轴矢量高斯光束
圆屏衍射
矢量瑞利衍射积分公式 相似文献