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1.
In order to update the beam power from 100 k W to 500 k W in the China Spallation neutron source(CSNS) Phase, one of the important measures is to replace the 80 m long beam transport line between the present80 Me V linac injector and the rapid cycling synchrotron(RCS) to another kind of acceleration structure. In this paper, we proposed a scheme based on 324 MHz double-spoke superconducting cavities. Unlike the superconducting elliptical cavity and normal conducting coupled cavity linac(CCL) structure, the double-spoke cavity belongs to the TE mode structure and has a smaller transverse dimension compared with that of the TH mode one. It can work at base frequency as the drift tube Linac(DTL) section, so that the cost and complexity of the RF system will be much decreased, and the behaviors of the beam dynamics are also improved significantly because of the low charge density and larger longitudinal acceptance. Furthermore, because of the relatively longer interactive length between the charged particle and the electromagnetic field per cell, it needs relatively less cell numbers and it has larger velocity acceptance compared with the double frequency TH structures. The superconducting section consists of 14 periods, each of which includes 3 superconducting cavities encapsulated in one cryomodule and a doublet in room temperate. The general considerations on cavity and beam dynamics design are discussed and the main results are presented.  相似文献   
2.
For the injector Scheme-Ⅰ test stand of the China-ADS (Accelerator Driven subcritical System), a beam with the maximum power of 100 kW will be produced and transported to the beam dump. To solve the very high thermal load problem at the dump, two measures are taken to deal with the huge power density at the target. One is to enlarge the contact area between the beam and the target, and this is to be accomplished by expanding the beam profile at the target and using slanted target plates. The other is to produce a more homogenous beam profile at the target to minimize the maximum power density. Here the beam dump line is designed to meet the requirement of beam expansion and homogenization at 3 different energies (3.2 MeV, 5 MeV and 10 MeV), and the step-like field magnets are employed for the beam spot homogenization. Taking into account the fact that the space charge effects are very strong at such low beam energies, the simulations have included space charge effects and errors which show that the beam line can meet the requirements very well. In the meantime, the alternative beam design using standard multipole magnets is also presented.  相似文献   
3.
通过对不同化学溶液和冻融循环共同作用下砂浆物理力学特性进行室内试验,研究了溶液的酸碱性、浓度和化学成分对砂浆化学冻融损伤劣化程度的影响,进一步分析了化学冻融后试样物理力学特性的变化规律,并对不同化学溶液下砂浆的冻融损伤劣化机理进行了探讨。试验结果表明:溶液酸性越强,砂浆物理力学参数的冻融损伤劣化程度越大;冻融初期,碱性NaOH溶液抑制了砂浆的损伤劣化的程度,但随着冻融循环次数的增加,这种抑制作用逐渐消失。相同条件下,Na_2SO_4溶液加剧了砂浆的冻融损伤程度。试样抗折强度的化学冻融损伤劣化程度相对于其抗压强度要严重得多;同时,基于化学冻融前后砂浆的孔隙率建立损伤变量,来定量地描述砂浆化学冻融损伤的劣化程度。  相似文献   
4.
旅行商问题(TSP)是运筹学中最典型的NP难题之一.研究了非对称TSP最优路程下界如何确定的问题.为了更加突出TSP问题非对称的特性,提出了入边和出边等概念,给出了确定TSP问题最优路程下界的有关定理,又给出了路程调整值的计算方法,从而得到了最优路程更精确的下界,更好地刻画了路程的逼近程度,最后结合实例对定理进行了说明,它表明给出的方法是有效的.  相似文献   
5.
For the injector Scheme- test stand of the China-ADS(Accelerator Driven subcritical System), a beam with the maximum power of 100 k W will be produced and transported to the beam dump. To solve the very high thermal load problem at the dump, two measures are taken to deal with the huge power density at the target.One is to enlarge the contact area between the beam and the target, and this is to be accomplished by expanding the beam profile at the target and using slanted target plates. The other is to produce a more homogenous beam profile at the target to minimize the maximum power density. Here the beam dump line is designed to meet the requirement of beam expansion and homogenization at 3 different energies(3.2 Me V, 5 Me V and 10 Me V), and the step-like field magnets are employed for the beam spot homogenization. Taking into account the fact that the space charge effects are very strong at such low beam energies, the simulations have included space charge effects and errors which show that the beam line can meet the requirements very well. In the meantime, the alternative beam design using standard multipole magnets is also presented.  相似文献   
6.
金属材料脆性断裂机理的实验研究   总被引:1,自引:0,他引:1  
材料的脆性断裂有许多准则和模型,但对脆断机理和变化规律缺乏合理的描述,给工程应用带来不便。本文对典型脆性材料球墨铸铁、灰铸铁分别进行了拉扭双轴断裂实验和常规拉伸、扭转破坏实验;对韧性金属材料合金钢进行了单轴拉伸颈缩破坏实验。通过上述实验分析了脆性材料和韧性材料发生脆性断裂的机理特征并选择应力三维度作为应力状态参数描述危险点的应力状态,同时考察了脆性材料和韧性材料发生脆性断裂的主导因素。结果表明:韧性材料45#钢和14CrNiMoV合金钢在颈缩断面心部应力三维度值较大时发生脆性拉断,而在颈缩断面边缘处应力三维度值较小时发生剪断;脆性材料球墨铸铁在应力三维度值为0.0~0.33之间变化时均发生脆性断裂;灰铸铁在应力三维度值大于0.0时发生脆性拉断,而在应力三维度值小于0.0时发生剪断。因此可以认为,材料的细观组织结构和危险点应力状态是影响断裂机理及变化规律的主要因素。对于同种材料,随着应力三维度代数值从小向大变化材料的断裂机制由塑性剪切断裂逐渐转变为脆性断裂。本文通过对几种材料的脆性断裂危险点和断裂方向的研究给出了脆断宏观破坏条件。  相似文献   
7.
8.
袁长迎  炎正馨  蒙瑰  李智慧  尚丽平 《物理学报》2010,59(10):6908-6913
采用恒流驱动耦合机械斩波技术在激光光声光谱装置上系统测量了5%—100%宽浓度范围甲烷气体的共振光声信号,发现在高浓度区共振光声信号呈现异常的饱和特征.基于气体吸收和光声光谱原理定量分析了光声信号饱和的主要原因及影响因素,研究表明,气体样本对入射光强吸收而导致的声源与本征共振模式的耦合系数改变是异常饱和的主要原因,并导出判定光声信号饱和深度的准则以用于判定高浓度气体饱和深度。  相似文献   
9.
预焙阳极微量元素XRF测定方法的研究   总被引:1,自引:0,他引:1  
使用X射线荧光光谱法测定预焙阳极中的微量和痕量元素,以粉末压片法制样,选用瑞士R&D碳素公司的C-300系列标准样品,并用仪器软件Super Q中提供的飞利浦模式的经验系数(Classic)和铑(Rh)靶康普顿散射线内标法校正元素间的谱线重叠干扰和基体效应,通过充分研磨样品消除颗粒效应,使用Magix(PW2403)X射线荧光光谱仪对样品中的F、Na、Mg、Al、Si、P、S、C1、K、Ca、Ba、Ti、V、Cr、Mn、Fe、Ni、Cu、Zn、Ph、Sr和Sn共22个元素进行测定,11次测定的相对标准偏差小于10%,多数元素的检出限小于1μg·g^-1。用R&D标准样品的混合样验证,测量结果与标准值的误差在化学分析允许范围内。  相似文献   
10.
HIRFL新B1聚束器冷却系统设计   总被引:1,自引:1,他引:0       下载免费PDF全文
在利用 MAFIA程序计算得到的新 B1聚束器腔体表面电流分布的基础上 ,提出了新 B1聚束器的冷却方案 ,并计算了水流及水管表面的电流分布 ,得到了冷却所需要的流量。最后估计了由于工作温度的升高所引起的并联阻抗的减小及频率的漂移。  相似文献   
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