Fabrication of a Low-Loss SSC Using High-Dose Electron Beam Lithography Exposure With Negative PMMA Resist

A silicon-on-insulator optical fiber-to-waveguide spot-size converter (SSC) using Poly-MethylMethAcrylate (PMMA) is presented for integrated optical circuits. Unlike the conventional use of PMMA as a positive resist, it has been successfully used as a negative resist with high-dose electron exposure for the fabrication of ultrafine silicon wire waveguides. Additionally, this process is able to reduce the side-wall roughness, and substantially depresses the unwanted propagation loss. Exploiting this technology, the authors demonstrated that the SSC can improve coupling efficiency by as much as over 2.5 dB per coupling facet, compared with that of SSC fabricated with PMMA as a positive resist with the same dimension.

SOI optical switch matrix integrated with spot size converter (SSC) and total internal reflection (TIR) mirrors

SOI (Silicon on Insulator) based photonic devices has attracted more and more attention in the recent years. Integration of SOI optical switch matrix with isolating grooves, total internal reflection (TIR) mirrors and spot size converter (SSC) was studied. A folding re-arrangeable non-blocking 4x4 optical switch matrix and a blocking 16x16 matrix with TIR mirrors and SSC were fabricated on SOI wafer. The performaces, including extinction ratio and the crosstalk, are better than before. The insertion loss and the polarization dependent loss (PDL) at 1.55 mu m increase slightly with longer device length, more bend and intersecting waveguides. The insertion losses decrease 2 similar to 3 dB when anti-reflection films are added in the ends of the devices. The rise and fall times of the devices are 2.1 mu s and 2.3 mu s, respectively.

SSC新高频腔设计与分析

Beam matching relationship between the two cyclotrons(SFC and SSC) of HIRFL is briefly discussed, and the frequency band of the new RF cavity is obtained. The new cavity is simulated with the three-dimensional electromagnetic calculation code MAFIA, and the parameters of it such as frequency, Q value, shunt impedance and voltage distribution are worked out and discussed. The simulation results show that the new RF cavity can fully meet the requirements of physics design and space configuration.中文摘要：简要分析了HIRFL SFC与SSC之间的束流匹配关系,给出了新高频腔的频率范围。利用经典三维电磁场数值模拟软件MAFIA对SSC新高频腔体进行了模拟计算,得出了SSC新高频腔体的相关物理参数,并对频率范围、Q值、并联阻抗和电压分布等参数进行了分析。高频腔体的模拟计算结果完全符合SSC回旋加速器改造的物理设计及空间结构要求。

SSC新高频腔设计与分析

简要分析了HIRFL SFC与SSC之间的束流匹配关系,给出了新高频腔的频率范围。利用经典三维电磁场数值模拟软件MAFIA对SSC新高频腔体进行了模拟计算,得出了SSC新高频腔体的相关物理参数,并对频率范围、Q值、并联阻抗和电压分布等参数进行了分析。高频腔体的模拟计算结果完全符合SSC回旋加速器改造的物理设计及空间结构要求。

SFC和SSC的束流匹配

描述了兰州重离子加速器中两台等时性回旋加速器的匹配现状,提出了几种可达到100%匹配效率的方法并进行了比较,得到了最佳方案.并叙述了该方案其他的优越性.

SSC高频腔数值模拟及分析

SSC加速电压的提高对于HIRFL整体运行水平的提高具有重要的意义 .利用三维电磁场计算程序MAFIA对SSC高频腔体作了更为细致的分析 ,重新计算了腔体的主要参数 ,结合运行中的实际结果 ,对电压提高的可行性进行了初步分析 ;由于在大功率运行状态下 ,少量的功率损失都可能影响腔 -机系统的稳定性 ,所以同时利用MAFIA计算得到的结果 ,对功率耦合系统重新做了分析 ,得到了功率反射的理论极值及改进方案 .

轫致辐射能谱测定SSC高频腔体电压

介绍了利用轫致辐射能谱测定回旋加速器高频腔体电压的原理、方法及测量结果。该测量方法的优点在于采用非接触方式测量高频腔体电压 ,因而不改变高频腔体的谐振特性 ,并且不受高频频率的影响 ,测量的高频腔体电压准确可靠。

HIRFL-SSC注入引出位置调整控制系统的研制

介绍了兰州重离子加速器控制系统中分离扇回旋加速器 (SSC)注入引出静电偏转板控制系统的硬件结构和软件设计。该控制系统实现了对位置调整电机的计算机控制和 Windows界面操作 ,使SSC注入引出位置调整更加方便和准确。

SSC注入系统能量接收范围的研究

分析了影响 SSC注入能量的因素和 SSC注入系统适应能量变化的能力 ,计算了在理论等时场下 SSC注入系统对 3种典型离子 O8+,Xe2 2 +和 Ar15+的能量可接收范围 ,找出了加速较轻的重离子时束流损失较大的部分原因 .

SFC和SSC径向探针的圈图测量软件设计

在 WINDOWS环境下 ,采用面向对象程序设计方法 ,建立了 HIRFL两台回旋加速器 SFC和 SSC的圈图测量软件及相应的探针控制系统 ,实现了数据采集、探针移动、圈图显示、图形打印、数据保存等多项功能 ,使设备工作更稳定可靠 ,大大提高了加速器运行和调束工作效率。

Beam matching between SFC and SSC

The beam matching status between the two isochronous cyclotrons in the Heavy Ion Research Facility at the Lanzhou-Cooling Storage Ring (HIRFL-CSR) is described. Several methods which can be used to accomplish 100% matching are proposed. By comparing of them, the best method is determined. The advantage due to this method is discussed.

A Particle-in-cell scheme of the RFQ in the SSC-Linac

A 52 MHz Radio Frequency Quadrupole (RFQ) linear accelerator (linac) is designed to serve as an initial structure for the SSC-Linac system (injector into Separated Sector Cyclotron). The designed injection and output energy are 3.5 keV/u and 143 keV/u, respectively. The beam dynamics in this RFQ have been studied using a three-dimensional Particle-In-Cell (PIC) code BEAMPATH. Simulation results show that this R,FQ structure is characterized by stable values of beam transmission efficiency (at least 95%) for both zero-current mode and the space charge dominated regime. The beam accelerated in the RFQ has good quality in both transverse and longitudinal directions, and could easily be accepted by Drift Tube Linac (DTL). The effect of the vane error and that of the space charge on the beam parameters have been studied as well to define the engineering tolerance for RFQ vane machining and alignment.

Design optimization of the APF DTL in the SSC-linac

A linear accelerator as a new injector for the SSC (Separated Sector Cyclotron) of the HIRFL (Heavy ton Research Facility Lanzhou) is being designed. The DTL (Drift-Tube-Linac) has been designed to accelerate U-238(34+) from 0.140 MeV/u to 0.97 MeV/u. To the first accelerating tank which accelerates U-238(34+) to 0.54 MeV/u, the approach of Alternating-Phase-Focusing (APF) is applied. The phase array is obtained by coupling optimization software Dakota and beam optics code LINREV. With the hybrid of Multi-objective Genetic Algorithm (MOGA) and a pattern search method, an optimum array of asynchronous phases is determined. The final growth, both transversely and longitudinally, can meet the design requirements. In this paper, the deign optimization of the APF DTL is presented.

SSC高频计算机控制系统之软件设计

高频系统是HIRFL系统中一个很重要的组成部分。其工作的稳定性和可靠性直接影响到束流的大小和品质，通过远程计算对其控制的目的不仅使人们远离现场恶劣的工作环境，而且在于提高整个系统的稳定性和可行性。高频计算机控制系统（RFC）的控制对象就是这个高频系统，它包括两个高频机和三个稳定系统：频率稳定系统、相位稳定系统、幅度稳定系统。考虑到整个系统长时间的工作状况和对稳定性和可靠性的严格要求，系统在硬件接口上选择了具有标准接口和强的扩展能力的CAMAC系统。CAMAC机箱的串行连接通过接口板2926和计算机联系在一起。在CAMAC串行总线上共有4个机箱分别负责高频机、相位、幅度和频率系统。这套系统的软件工作在Windows98操作系统平台下。有三个部分组成软件部分：一是漂亮友好交互性强的界面，这部分是通过VB和VC混合编程得来。二是功能稳定、可靠性强的接口，这部分是在VC中建立DLL来完成最终驱动。还有一部分是数据库，这个数据库是由Access生成，用于存储程序中的参数和高频系统的运行参数。这三个部分在界面程序中有机结合在一起共同完成对整套系统的控制作用。目前这套系统已经完成，运行在中控室的控制平台上，经过测试工作效果还很不错。本论文主要具体阐述了这套系统的组成，以及在程序设计时的思路、过程还有一些问题的解决办法等。