回旋加速器引出系统的传输矩阵和引出束发射度

推导了静电引出通道的等效简阶振荡方程(轴向),给出了引出系统的一阶传输矩阵:分析了引出束初始发射度椭圆矩阵的确定方法;给出了束发射度计算结果,并与国外同类型加速器的实测作了比较。     

束流能散度和传输管道孔径变化对束流尾场效应的影响

采用双粒子模型，讨论了束流能散度和传输管道孔径变化对由第一个宏粒子产生的束流尾场的影响。并将所得的计算尾场效应的公式，变换成六维传输矩阵的形式，使之能用于束流传输系统的模拟计算。     

旋转线圈测磁仪的结构误差对测量精度的影响

分析了旋转线圈测磁仪的测量精度和结构误差间的关系，给出了计算公式和实例。     

环形流道热入口区和变化热流的棒束流道中液态金属钠的传热

本文研究在环形流道热入口区以及壁面热流沿轴向变化的棒束流道中液金属钠的传热。首先求解在恒定的壁面热流的环形流道中的能量方程。然后把基本解推广到壁面热流沿轴向变化的棒束流道中。理论结果与实验结果吻合良好。研究结果表明,液钠的热入口效应与普通流体很不相同。     

重离子同步加速器中剥离累积时碳膜对束流的影响研究

治癌专用重离子加速器HITFiL中同步加速器的注入系统采用了剥离注入方式。剥离膜的存在使束流克服了刘维定理的限制从而累积达到较高流强,但粒子多次穿越剥离膜也会造成束流损失并使得束流品质变坏,其中包括:1)粒子从膜原子中俘获电子使粒子电荷态发生改变而导致束流损失;2)剥离膜对束流的多重库仑散射导致束流发射度增长;3)束流在剥离膜中的能损及能量岐离导致束流中心动量减少并使得动量分散增长。本文通过研究剥离注入过程中粒子与物质的相互作用规律,用蒙特卡罗方法建立了剥离膜与粒子的作用模型,在对ACCSIM程序改进的基础上研究了剥离膜对束流的影响。     

CYCIAE-100中心平面的Br对束流发射度的影响计算

在回旋加速器中，如果磁极的镜像对称被破坏，将在加速器的中心平面上产生一水平分量的场Br，在粒子相应轴向共振的作用下，这样的场将使中心粒子的运动偏离中心平面，进而使束流发射度发生变化。在回旋加速器中粒子由于径向磁场作用偏离中心平面运动的方程可表示为：     

尼尔逊离子源重离子束流的发射度

尼尔逊离子源已广泛地应用于重离子加速器、同位素分离器及研究用离子注入机。用于C-600离子注入机的尼尔逊离子源,目前已获得达100μA的三十余种重离子束,其中有近二十种固体元素。     

On abnormal behaviors of ion beam extracted from electron cyclotron resonance ion thruster driven by rod antenna in cross magnetic field

In a 2.45 GHz electron cyclotron resonance(ECR) ion thruster powered with rod antenna under a cross magnetic field, abnormal behaviours such as sudden drop of ion beam current(Ib) and larger increasing-rate of Ibin the high microwave power(Pw) discharges at high gas flow rates were observed. A differential method was proposed to reveal the changes in the radial profiles of gray values extracted from the end-view discharge images. The increasing-rate of Ibwith respect to Pwwas used to evaluate efficiencies of ion production and transport. Analyses indicate that discharges are dominantly sustained by ordinary wave via electron heating in the electron plasma resonance layer that can shift along the rod-antenna, and extraordinary wave can only ignite a discharge in the ECR layer in the low gas flow rate regime. In terms of the confinement region defined by the magnetic field lines intercepting with the screen grid, the confinement region of the optimized 2.45 GHz cross magnetic field takes the shape of hourglass, enabling the high increasing-rate of I_b with respect to P_w in high power discharges at high gas flow rates.Correlated with the accompanied bright boundary layer appearing in the differentiated image, the sudden drop of I_b in the low gas flow rate regime is attributed to the discharge ignited by the enhanced extraordinary wave in the ECR layer neighbouring the narrowest confinement region,where the produced ions can promptly enter the loss region.     

Influence of irradiation number of high current pulsed electron beam on the structure and properties of M50 steel

The influence of high current pulsed electron beam (HCPEB) irradiation numbers on the microstructure, wear and corrosion resistance properties of M50 steel was studied. The crystallize phase, surface morphology, hardness, oxidation wear and corrosion resistance of samples were analyzed using XRD, SEM, nanoindenter, wear tester and electrochemical corrosion tests. The results reveal that the hardness and wear resistance of irradiated samples decrease compared with untreated sample because of the increasing of austenite content in the melted layer; while the corrosion resistance of irradiated samples is higher than untreated sample.     

离子束混合对铝合金腐蚀行为影响的阳极极化研究

用离子束一次混合、二次混合和氧化处理在LY11硬铝合金基体上形成防护层。在3％NaCl溶液中采用三电极动电位扫描法测定各试样的一次阳极极化和环形极化曲线,比较其自然腐蚀电位、点蚀击穿电位、保护电位、可能点蚀区宽度以及极化电流等电化学参数。发现离子束二次混合形成的富Cr新合金层远优于一次混合或氧化处理的防护层。用RBS分析获得混层合金元素的纵向分布,证明在二次混合情况下,Cr与基体产生了良好的混合。     

Effect of the gas mixing technique on the production efficiency of ion beams extracted from an electron cyclotron resonance ion source

In this work the effect of gas mixing on the production efficiency of ion beams extracted from an ECR ion source has been studied with the JYFL 6.4 GHz electron cyclotron resonance ion source (ECRIS). It was found that the gas mixing affects strongly the confinement of ions in the plasma of the ECRIS. The information obtained can be used to minimize the consumption of expensive materials or isotopes and to reduce contamination of the plasma chamber. It was observed that the carbon contamination, which is built up when the MIVOC method is used could be decreased with the aid of the gas mixing technique. The best mixing gas for this purpose was found to be oxygen.     

Influence of two-stream relativistic electron beam parameters on the space-charge wave with broad frequency spectrum formation

We developed a cubic non-linear theory describing the dynamics of the multiharmonic spacecharge wave (SCW),with harmonics frequencies smaller than the two-stream instability critical frequency,with different relativistic electron beam (REB) parameters.The self-consistent differential equation system for multiharmonic SCW harmonic amplitudes was elaborated in a cubic non-linear approximation.This system considers plural three-wave parametric resonant interactions between wave harmonics and the two-stream instability effect.Different REB parameters such as the input angle with respect to focusing magnetic field,the average relativistic factor value,difference of partial relativistic factors,and plasma frequency of partial beams were investigated regarding their influence on the frequency spectrum width and multiharmonic SCW saturation levels.We suggested ways in which the multiharmonic SCW frequency spectrum widths could be increased in order to use them in multiharmonic two-stream superheterodyne free-electron lasers,with the main purpose of forming a powerful multiharmonic electromagnetic wave.     

Influence of magnetic filter field on the radio-frequency negative hydrogen ion source of neutral beam injector for China Fusion Engineering Test Reactor

In the design of negative hydrogen ion sources,a magnetic filter field of tens of Gauss at the expansion region is essential to reduce the electron temperature,which usually results in a magnetic field of around 10 Gauss in the driver region,destabilizing the discharge.The magnetic shield technique is proposed in this work to reduce the magnetic field in the driver region and improve the discharge characteristics.In this paper,a three-dimensional fluid model is developed within COMSOL to study the influence of the magnetic shield on the generation and transport of plasmas in the negative hydrogen ion source.It is found that when the magnetic shield material is applied at the interface of the expansion region and the driver region,the electron density can be effectively increased.For instance,the maximum of the electron density is 6.7×1017 m-3 in the case without the magnetic shield,and the value increases to 9.4×1017 m-3 when the magnetic shield is introduced.