HIAF-SRing的等时性模式光学设计

高精度环形谱仪SRing作为HIAF装置的核心之一,是获取高品质放射性次级束,并将束流用于加速器技术研究、原子物理及核物理实验的关键设备。SRing有三种运行模式:等时性模式、正常模式与内靶模式。等时性模式下,SRing运行在特殊线性光学设置下,可以精确测量寿命低至几十微秒的原子核的质量。介绍SRing等时性模式的线性光学及高阶项校正的设计方案。在使用程序GICOSY进行等时性高阶项校正数值计算后,将得到的光学传输矩阵输入到程序MOCADI进行粒子跟踪模拟。以γ_t=1.43的等时性模式为例,SRing的动量接收度为±0.20%,粒子跟踪结果显示,在仅满足一阶等时性条件时SRing的质量分辨能力R=1.6×104。在保证动量接收度不变的前提下,考虑了等时性高阶项校正后SRing的质量分辨能力提高到R=1.2×106,达到设计要求。The Spectrometer Ring, as the most important experiment terminal of the High Intensity heavy-ion Accelerator Facility (HIAF) project, is a key device to obtain high-quality radioactive ion beams (RIBs) for atomic physics, nuclear physics experiments and accelerator technology researches. Three operation modes including the isochronous mode, the normal mode and the internal target mode, have been designed for the SRing. In the isochronous mode, the SRing operates under a special ion optics and could be used for precision mass measurement of short-lived nuclei with half-life shorter than several tens of microseconds. This study aims to design the ion optics for the isochronous mode and improve the mass resolving power of the SRing with higher-order ion-optical correction scheme for isochronism while preserve a large momentum acceptance of SRing. The ion optics and the higher-order correction for the isochronous mode are calculated with the code MAD-X and GICOSY respectively. Three ion optics with γ_t=1.43, 1.67, 1.83 settings have been calculated. The code MCOADI which utilizes the matrixes generated by the code GICOSY is used for particles tracking to verify the correction results. For the ion-optical setting of γ_t=1.43 with a momentum acceptance of ±0.20%, the mass resolving power of the SRing could be improved from R=1.6×104 to R=1.2×106, after isochronous higher-order corrections.     

储存环HIAF-SRing等时性模式的非线性磁场影响研究

高精度环形谱仪SRing（Spectrometer Ring）是强流重离子加速器装置（HIAF）的重要组成部分,其等时性模式为远离β稳定线的短寿命原子核质量和寿命的精确测量提供国际领先的科研条件。为了扩大短寿命原子核质量测量精度和范围,SRing等时性模式设计了两种光学:γ_t=1.43和1.67。质量分辨是衡量等时性储存环的最重要参数。二极磁铁的高阶场以及磁铁的边缘场能强烈地引起束流光学高阶畸变,对质量分辨产生影响,因此需要高极磁铁对其进行校正。介绍了SRing等时性模式的线性计算,对非线性磁场的影响进行了详细研究。应用六极磁铁和八极磁铁对非线性场和发射度的影响进行了校正后,离子的循环时间标准偏差σ（T）/T达到3.5×10-7,质量分辨△m/m达到1×106。The isochronous mode of the Spectrometer Ring at the High Intensity heavy-ion Accelerator Facility (HIAF) project in China offers the capacity of measuring the mass and half-life of short-lived nuclides. The transition energy settings of the SRing are 1.43 and 1.67, which have been calculated in the same injection scheme. The resolution of mass or revolution time is the most important parameter of the isochronous mode design of a storage ring. The nonlinear magnetic field errors, including high-order magnet field of dipole, fringe field of magnets, have strongly effect to the resolution of revolution time. High-order corrections are required to improve the resolution of revolution time and mass. In this paper, the SRing linear isochronous optical were shown. The influence of nonlinear magnetic field errors on the revolution time resolving power were investigated. With 3 sextupole families and 1 octupole family corrections, the relative variation of revolution time reaches 4.6×10-7 with the momentum spread of ±0.2%. The relation of the relative standard revolution time deviation σ(T)/T and revolution turns was researched. With corrections of high-order isochronous condition and emittance influence by 3 sextupole families and 1 octupole family, one can reach a resolution of up to σ(T)/T=3.5×10-7, which corresponds to the mass resolution of △m/m=1×106.     

低能辐照离子源设计及性能

简要介绍了低能辐照离子源的设计及性能。采用热阴极磁约束ＰＩＧ放电,并用两极多孔加减速系统引出离子束。调试结果：离子束能量在２００－２０００ｅＶ范围内可调,最大引出束流１５０ｍＡ,灯丝工作寿命１６０ｈ。     

红外双焦无热化空间相机光学镜头设计

针对空间碎片探测相机光学镜头的设计要求,提出了一种全新的紧凑型、小型化、轻量化、高像质、可全天候工作、使用环境恶劣的光学镜头,突破了以往该类系统结构复杂、体积大、重量重、仅有一个焦距的瓶颈。利用衍射光学元件特殊的特性进行消色差和消热差设计,并利用锗和硅混合来校正系统色球差,最终设计镜头的焦距为30, 120 mm,相对孔径为1/4。设计结果表明,在空间频率16 lp/mm处,－40～60 ℃温度范围内,短焦距、长焦距的传递函数值分别优于0.45和0.55,接近衍射极限;短焦距、长焦距的最大RMS弥散斑直径分别为15.8, 7.2 m,远小于探测器像元尺寸30 m,表明该系统在实际使用温度环境下具有良好的成像质量。     

强流重离子加速器装置的增强器慢引出系统

中国科学院近代物理研究所承担的强流重离子加速器装置目前已进入了初步设计阶段。增强器作为该装置的主加速器,可利用双向涂抹技术将238U35+束的粒子数累积至1.0×1011,并将其从注入能量为17 MeV/u加速至高能量,引出能量的范围为200-835 MeV/u。为了提供s量级的准连续束以开展辐照实验,增强器中设计了慢引出系统,该系统将采用三分之一共振与RF-knockout的引出方法。同步加速器中有两种不同种类的六极磁铁,用于实现色品校正与共振驱动,并在设计中考虑了两者能同时运行并互不影响。针对增强器中不同引出能量的238U35+束,对其相应的稳定接受度模拟结果进行了比较,并给出了在引出静电偏转板处的光学匹配参数,这将为增强器中重离子束的慢引出及放射性次级束流分离器的入口光学设计提供重要的理论依据。     

100MeV强流质子回旋加速器轴向注入系统和中心区物理设计

100MeV强流质子回旋加速器设计的引出质子束流强为大于200μA, 并计划提供脉冲束流. 轴向注入系统设计有两条注入线, 即1#和2#注入线. 1#注入线利用负氢束的中性化以解决强流连续束流的注入,为保证达到高中性化程度, 横向聚焦均采用磁元件; 2#注入线的设计目的主要是提供一定流强的脉冲化束流,由于脉冲化负氢束的中性化过程难以建立, 因此, 横向聚焦元件均为静电元件. 两条线合理的结构设计使得注入系统可方便切换运行模式. 采用包含空间电荷力的光学计算程序, 匹配不同中性化程度的注入束流光学特性, 匹配工作的重点在于高达40°的高频相位接收度. 从离子源出口到粒子加速前15圈的连续匹配计算结果表明: 所设计的注入系统可有效地控制束流包络, 减少束流损失; 中心区高的高频接收度使设计的100MeV质子回旋加速器具有加速强流负氢束的能力.     

由等离子体引出强流离子束的光学数值模拟

本文叙述了中性束注入器中的强流离子源引出系统离子束光学性质的数值模拟方法,并给出了典型计算结果。计算结果表明:用这种方法能反映强流离子源引出系统最本质的束光学性质,可供选取和研究强流离子束光学系统之用。     

低能辐照离子源的设计及性能

简要介绍了低能辐照离子源的设计及性能。采用热阴极磁约束ＰＩＧ放电，并用两极多孔加减速系统引出离子束。调试结果：离子束能量在２００－２０００ｅＶ范围内可调，最大引出速流１５０ｍＡ，灯丝工作寿命１６０ｈ。     

高精度环形谱仪等时性模式的闭轨校正模拟

高精度环形谱仪（SRing）是HIAF装置的重要组成部分,闭轨校正设计是该同步加速器设计的关键部分。由于等时性模式（γ_t=1.43）线性光学水平β函数很大,磁铁场误差及安装误差会引起较大的闭轨畸变,并导致线性光学发生变化。模拟过程采用奇异值分解（SVD）算法,通过多次计算响应矩阵并计算校正铁校正量实现闭轨校正。同时考虑BPM误差的影响,并通过减少特征值使用个数降低校正铁校正量。校正后全环最大闭轨小于0.8 mm,线性光学也得到明显优化。     

圆形加速器的注入和引出技术

圆形加速器中的注入引出通常是关键性的系统,它们在从一个加速阶段到另一个加速阶段或从加速器到实验系统的柬流传输中起到重要作用.注入引出区通常也是发生较大柬流损失的地方.受制于空间限制和尽可能减小对循环束的干扰的要求,注入引出的电磁设备设计通常都需要满足不少特殊的要求如:紧凑性、低杂散场、快上升或下降时间等等.常用的注入引出元件包括:切割磁铁、冲击磁铁、静电偏转板、慢凸轨磁铁和剥离膜等.尽管不同的加速器类型和具体设计对注入引出系统的要求是不一样的,但很多设计和制造中的技术和工艺是类似的,可以在不同实验室中共享.本文给出了国内主要的圆形加速器所采用的注入和引出技术的综述.     

HIAF随机冷却系统slot-ring型pickup/kicker及相应合路器/功分器的设计与仿真

为降低束流发射度,提高束流强度,得到高品质的束流,强流重离子加速器装置(HIAF)高精度环形谱仪(SRing)将建造随机冷却系统。随机冷却系统的关键硬件pickup/kicker在一定程度上决定了其冷却效率。本工作讨论了随机冷却系统pickup/kicker的具体作用及设计指标,介绍了分路阻抗概念。SRing随机冷却系统采用周期性单元结构slot-ring模型,利用高频结构仿真(HFSS)软件对其进行建模并仿真优化。通过对不同结构参数进行扫参,确认了slot-ring结构各参数对pickup/kicker分路阻抗值的影响。仿真结果表明,slotring结构有较高的分路阻抗,适用于SRing随机冷却系统。同时,考虑到pickup/kicker工作带宽内分路阻抗的平坦度,提出了采用不同尺寸slot-ring结构进行组合的方式来优化其平坦度。最后设计并加工实测了该slot-ring结构相匹配的十六路功率分配器/功率合成器,实测结果表明：该功分器/合路器具有各端口输出幅度平坦度较好、隔离度大、插入损耗低、电压驻波比小等特点,满足SRing随机冷却系统的要求。     

托卡马克中宏观束-等离子体扭曲模不稳定性研究

本文主要研究了具有单一高能离子分量的托卡马克等离子体扭曲模宏观不稳定性。它基本上模拟了中性束平行注入经过电离和电荷交换后在本底等离子体中维持一个稳恒等离子体流的物理过程。高能和本底都用无碰撞的Vlasov等离子体,并取了低频、小拉莫尔半径极限。由于主要考虑束-等离子体无耗散宏观不稳定性,故可用能量原理来分析。结果表明,高能离子束对本底等离子体的外部模没有影响,只影响内部扭曲模的增长率和扰动振幅。对适当选择的速度剖面,束能够完全稳定体系n≥2,m=1模,与Dunlap线性理论结果相反而与目前实验观测一致。m/n=1/1内部扭曲模增长率在所取得模型下随注入能量β_b,注入功率P_bw,轴上安全因子q(0)和束速度的径向剖面分布参数S的不同而出现增稳、减稳及完全稳定的行为。适当选择S,在q(0)<0.924时,高能束能够稳定m/n=1/1模。 关键词：     

Disruption avoidance in the Frascati Tokamak Upgrade by means of magnetohydrodynamic mode stabilization using electron-cyclotron-resonance heating

Disruption avoidance by stabilization of MHD modes through injection of ECRH at different radial locations is reported. Disruptions have been induced in the FTU (Frascati Tokamak Upgrade) deuterium plasmas by Mo injection or by exceeding the density limit (D gas puffing). ECRH is triggered when the V(loop) exceeds a preset threshold value. Coupling between MHD modes (m/n=3/2, 2/1, 3/1) occurs before disruption. Direct heating of one coupled mode is sufficient to avoid disruptions, while heating close to the mode leads to disruption delay. These results could be relevant for the International Thermonuclear Experimental Reactor tokamak operation.     

Multifunctional silicon-based light emitting device in standard complementary metal–oxide–semiconductor technology

A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 μ m complementary metal--oxide--semiconductor technology. This device is capable of versatile working modes: it can emit visible to near infra-red (NIR) light (the spectrum ranges from 500 nm to 1000 nm) in reverse bias avalanche breakdown mode with working voltage between 8.35 V--12 V and emit NIR light (the spectrum ranges from 900 nm to 1300 nm) in the forward injection mode with working voltage below 2 V. An apparent modulation effect on the light intensity from the polysilicon gate is observed in the forward injection mode. Furthermore, when the gate oxide is broken down, NIR light is emitted from the polysilicon/oxide/silicon structure. Optoelectronic characteristics of the device working in different modes are measured and compared. The mechanisms behind these different emissions are explored.     

放射性次级束流分离器真空系统的压力分布

放射性次级束流分离器是强流重离子加速器装置中,连接增强器和高精度环形谱仪的束流输运线,用于传输重离子束流以及放射性次级束流。为了满足束流传输的要求,并维持相连增强器和高精度环形谱仪的极高真空,放射性次级束流分离器真空系统的平均压强应低于5×10-7 Pa。因此,需要验证真空系统设计方案的可行性,以及设计方案能否满足要求的压强范围。通过现有的同步储存环CSRm中的真空计监测数据以及软件BOLIDE的模拟结果对比,对真空压力计算软件VAKTRAK的使用方法和计算结果进行验证;采用VAKTRAK模拟计算不同真空参数下（流导、出气率以及泵速）放射性次级束流分离器真空系统的压力分布。根据计算结果,放射性次级束流分离器真空系统的平均压强可以达到1.79×10-7 Pa （H₂）,满足物理实验和工程设计的要求。通过模拟计算结果,放射性次级束流分离器真空系统的设计方案的可行性得到验证,系统设计的真空度满足要求。HIAF Fragment Separator(HFRS) is connected with Booster Ring(BRing) and Spectrometer Ring (SRing) in the HIAF and used to transfer the ion beams and radioactive secondary beams. To satisfy the requirements of beam transmission and maintain the extremely high vacuum of BRing and SRing, the average pressure of HFRS vacuum system should be lower than 5×10-7 Pa. Therefore, the feasibility of the design scheme and whether the design scheme would fulfill the required vacuum range or not should be verified. Based on the measured data on the current sychrontron CSRm and the simulation results of BOLIDE, the calculation results of VAKTRAK are verified and then VAKTRAK is used to calculate the pressure profiles of different parameters(such as the conductance, out-gassing and pumping speed) for HFRS. According to the calculation results, the average pressure of HFRS vacuum system could be 1.79×10-7(H₂) which achieves the required pressure for physics experiments and engineering design. According the calculation results of this paper, the feasibility of the designed HFRS vacuum system has been verified and the design of system satisfies the vacuum requirements.     

Nonlinear mid-IR radiation in two-frequency semiconductor lasers with a corrugated waveguide

The nonlinear generation of a difference frequency mode in an injection quantum-well semiconductor laser is considered. A laser based on the InGaAs/GaAs/InGaP heterostructure is proposed, which generates two modes in the 1-μm range and the difference mode in a corrugated waveguide in the range from 10 to 20 μm. It is shown that the power of the difference mode produced by a laser with a 100-μm-wide waveguide in the mid-IR range at room temperature can be as high as a few microwatts if the power of the short-wave modes is 10 W.