大功率电子加速器的辐射灭菌效果研究

To study the effects of radiation sterilization of the electron beam,the three species of microorganisms,Escherichia.coli,Staphylococcus aureus and Proteus vulgaris were irradiated with the electron beam,delivered by the electron accelerator independently developed by the Institute of Modern Physics,Chinese Academy of Sciences,and the changes of superoxide dismutase(SOD) activity of these irradiated microorganisms were also tested.The results indicated that the Staphylococcus aureus were fully radio-sterili...中文摘要：在中国科学院近代物理研究所自行研制的大功率电子加速器上,研究了不同辐照剂量的电子束对大肠杆菌、金黄色葡萄球菌和变形杆菌3种微生物的杀灭效果,同时检测了辐照后菌体超氧化物歧化酶(SOD)活性的变化。结果显示:辐照剂量达到2.0 kGy时,可完全杀灭金黄色葡萄球菌,2.2 kGy时可完全杀灭大肠杆菌和变形杆菌;辐照对3种微生物的SOD活性有较显著的影响。

HIRFL-CSR commissioning in 2006 and 2007

HIRFL-CSR, a new heavy ion cooler-storage-ring system at IMP, had been in commissioning since the beginning of 2006. In the two years of 2006 and 2007 the CSR commissioning was finished, including the stripping injection (STI), electron-cooling with hollow electron beam, C-beam stacking with the combination of STI and e-cooling, the wide energy-range synchrotron ramping from 7 MeV/u to 1000 MeV/u by changing the RF harmonic-number at mid-energy, the multiple multi-turn injection (MMI), the beam accumulation with MMI and e-cooling for heavy-ion beams of Ar, Kr and Xe, the fast extraction from CSRm and single-turn injection to CSRe, beam stacking in CSRe and the RIBs mass-spectrometer test with the isochronous mode in CSRe by using the time-of-flight method.

Relativistic Distorted-Wave Collision Strengths of Ni-, Cu- and Zn-like Au Ions

Excitation energies and electron impact excitation strengths from the ground states of Ni-, Cu- and Zn-like Au ions are calculated. The collision strengths are computed by a 213-levels expansion for the Ni- like Au ion, 405-levels expansion for the Cu-like Au ion and 229-levels expansion for the Zn-like Au ion. Configuration interactions are taken into account for all levels included. The target state wavefunctions are calculated by using the Grasp92 code. The continuum orbits are computed in the distorted-wave approximation, in which the direct and exchange potentials among all the electrons are included. Excellent agreement is found when the results are compared with previous calculations and recent measurements.

ATOMIC PHYSICS RESEARCHES AT COOLER STORAGE RING IN LANZHOU

The commissioning of the cooler storage rings (CSR) was successful, and the facility provides new possibilities for atomic physics with highly charged ions. Bare carbon, argon ions, were successfully stored in the main ring CSRm, cooled by cold electron beam, and accelerated up to 1 GeV/u. Heavier ions as Xe44+ and Kr28+ were also successfully stored in the CSRs. Both of the rings are equipped with new generation of electron coolers which can provide different electron beam density distributions. Electron-ion interactions, high precision X-ray spectroscopy, complete kinematical measurements for relativistic ion-atom collisions will be performed at CSRs. Laser cooling of heavy ions are planned as well. The physics programs and the present status will be summarized.

Experimental studies of the dissociative recombination of CD3CDOD+ and CH3CH2OH2+

Aims. We determine branching fractions, cross sections and thermal rate constants for the dissociative recombination of CD3CDOD+ and CH3CH2OH2+ at the low relative kinetic energies encountered in the interstellar medium. Methods. The experiments were carried out by merging an ion and electron beam at the heavy ion storage ring CRYRING, Stockholm, Sweden. Results. Break-up of the CCO structure into three heavy fragments is not found for either of the ions. Instead the CCO structure is retained in 23 +/- 3% of the DR reactions of CD3CDOD+ and 7 +/- 3% in the DR of CH3CH2OH2+, whereas rupture into two heavy fragments occurs in 77 +/- 3% and 93 +/- 3% of the DR events of the respective ions. The measured cross sections were fitted between 1-200 meV yielding the following thermal rate constants and cross-section dependencies on the relative kinetic energy: sigma(E-cm[eV]) = 1.7 +/- 0.3 x 10(-15)(Ecm[eV])(-1.23 +/- 0.02) cm(2) and k(T) = 1.9 +/- 0.4 x 10(-6)(T/300)-0.73 +/- 0.02 cm(3) s(-1) for CH3CH2OH2+ as well as k(T) = 1.1 +/- 0.4 x 10(-6)(T/300)(-0.74 +/- 0.05) cm(3) s(-1) and s(Ecm[eV]) = 9.2 +/- 4 x 10(-16)(Ecm[eV])-1.24 +/- 0.05 cm(2) for CD3CDOD+

石英管对中低能电子束的导向作用研究

本工作研究了四种不同形状和尺寸的石英管对1100eV、1300eV、1500eV三种能量电子束的导向作用，并把四种实验结果进行了分析对比。四种石英管分别为等径圆柱形弯曲管、等径圆柱形直管、直锥形管以及弯曲锥形管，它们的内径均在毫米量级。实验中利用一个位置灵敏法拉第筒对从石英管出射的电子束进行探测，获得从管道中出射的电子束流强度在位置灵敏法拉第筒各道上的强弱分布，其结果显示宏观尺寸石英管对电子束存在导向作用。对于等径圆柱形石英管，入射电子束流的强度越强，其导向作用越明显；然而对于锥形管，导向作用并不明显，且不随入射电子束流强度增加有明显的变化。此外，实验结果在一定程度上显示出石英管对中低能电子束的导向能力并不取决于管的形状。石英管导向能力与管的尺寸、形状及材料之间的关系还有待进一步的研究

加器束流强度和能量稳定控制系统

本文基于中国科学院的代物理研究所电子辐照室的谐振变压器型电子加速器计算机控制系统的研制工作。首先介绍了研制此种加速器的国际、国内的历史背景和前景，接着介绍了加速器的结构和工作原理，描述了加速器的计算机控制系统，着重介绍了加速器的束流强度稳定系统和能量稳定系统。在束流强度稳定系统中，首先介绍了束流稳定系统的工作原理、实现的方法和对灯丝加热电源的要求；通过对灯丝电源的控制达到对束流强度调节和稳定的目的。而灯丝电源处在IMV左右的高压端，为此设计了光路传输系统，把高压端与低压端隔离开，同时又能传输控制信号。用一台可编程序控制器（PLC）作为主要控制硬件完成控制任务，同时编写了PLC控制软件。对于能量稳定系统，介绍了其工作原理、外部硬件组成（包括另一台PLC站）。针对能量稳定系统的特殊要求，在软件方面设计两种工作模式：变频器稳定模式和加速器调试和维修使用。以上两个控制站都有完备的报菟显示功能。使用组态王5.0开发了上位机（工控机）的动态显示画面，它能完成计算机控制命令的发布、参数显示和随机修改控制参数等功能。实验表明以上工作都达到设计要求，效果良好。

CSR电子冷却中电子束的空间电荷效应研究

电子冷却是利用具有相同平均速度运动的强流冷电子束与热的离子束在储存环的一小部分相互重叠，通过多次库仑相互作用，达到降低束流发射“度和动量散度，改善束流品质的一种有效方法。HIRFL-CSR就是采用电子冷却方法迅速压缩储存环中离子束的横向包络、发散角和纵向动量散度，从而获得高品质的重离子束流。论文论述了两体碰撞模型，得到了冷却力和冷却时间的解析表达式；并以此为依据，编程模拟了冷却过程对储存环中离子束发射度和动量散度的影响。本论文的重点是通过求解强流电子束自身的空间电荷场，得到了电子束速度的径向梯度分布；获得了电子束在自身空间电荷场和螺线管纵向磁场的作用下产生横向漂移速度和由此引起的电子束横向温度的变化。为了减小强流电子束的空间电荷场，CSR的电子冷却系统将首次采用空心电子束对储存环中的重离子束流进行冷却。分析了空心电子束的空间电荷场，研究了其对电子束速度和电子束温度的影响，并将结果与实心束的情形进行了详细地比较。与此同时，利用电子束密度的K-V分布，研究了强流电子束在纵向螺线管场中运动的包络方程，采用数值计算方法，得到了CSR电子冷却系统强流电子束在冷却段螺线管中的包络振荡特性。另外，论文还对电子冷却在储存环中的附加影响进行了一些探讨。从Betatron运动方程出发研究了斜四极场和螺线管场存在时束流的幅度的耦合效应，理论上分析了斜四极场存在时束流发射度的变化；通过求解储存环中粒子束的空间电荷场，计算了CSRm中的粒子束空间电荷效应造成的储存环工作点的移动；对于强流电子束空间电荷场对储存环的频移大小也进行了分析；此外，对电子冷却对储存环中束流寿命的影响进行了初步研究。论文最后对CSrm35keV电子冷却系统的机械安装、磁场的测量以及初步的调试结果也给予了介绍。

Influence of the deposition energy on the composition and thermal cycling behavior of La-2(Zr0.7Ce0.3)(2)O-7 coatings

Lanthanum-zirconium-cerium composite oxide (La-2(Zr0.7Ce0.3)(2)O-7, LZ7C3) coatings were prepared under different conditions by electron beam-physical vapor deposition (EB-PVD). The composition, crystal structure, surface and cross-sectional morphologies, cyclic oxidation behavior of these coatings were studied. Elemental analysis indicates that the coating composition has partially deviated from the stoichiometry of the ingot, and the existence of excess La2O3 is also observed.

Effect of diffusion barrier on the high-temperature oxidation behavior of thermal barrier coatings

A selective oxidation technique has been applied to form a diffusion barrier on the Ni-based superalloy substrate by heating the substrate with electron beam of the electron beam-physical vapor deposition (EB-PVD) facility. The interdiffusion behavior, cross-sectional morphology, isothermal and cyclic oxidations were studied for thermal barrier coatings (TBCs) with and without diffusion barrier.

Effects of deposition conditions on composition and thermal cycling life of lanthanum zirconate coatings

Lanthanum, zirconate (La2Zr2O7, LZ) coatings were prepared under four different deposition conditions by electron beam-physical vapor deposition (EB-PVD). The composition, crystal structure, surface and cross-sectional morphology, cyclic oxidation behavior of these coatings were studied. Elemental analysis indicates that the coating composition has partially deviated from the stoichiometry of pyrochlore, and the existence of excess La2O3 is also observed. The deviation could be reduced by properly controlling the electron beam current or by changing the ingot composition.

Adhesive strength of new thermal barrier coatings of rare earth zirconates

La2Zr2O7 (LZ) and La-2(Zr0.7Ce0.3)(2)O-7 (LZ7C3) as novel candidate materials for thermal barrier coatings (TBCs) were prepared by electron beam-physical vapor deposition (EB-PVD). The adhesive strength of the as-deposited LZ and LZ7C3 coatings were evaluated by transverse scratch test. Meanwhile, the factors affecting the critical load value were also investigated. The critical load value of LZ7C3 coating is larger than that of LZ coating, whereas both values of these two coatings are lower than that of the traditional coating material, i.e. 8 wt% yttria stabilized zirconia (8YSZ). The micro-cracks formed in the scratch channel can partially release the stress in the coating and then enhance the adhesive strength of the coating. The width of the scratch channel and the surface spallation after transverse scratch test are effective factors to evaluate the adhesive strength of LZ and LZ7C3 coatings.

Preparation and characterization of La2Zr2O7 coating with the addition of Y2O3 by EB-PVD

Thermal barrier coatings (TBCs) of La2Zr2O7 (LZ) with the addition of 3 wt.% Y2O3 (LZ3Y) were deposited by electron beam-physical vapor deposition (EB-PVD). The phase stabilities, thermophysical and mechanical properties, and chemical compositions of these ceramics and coatings were studied in detail. The phase stability and thermal expansion behavior of LZ3Y bulk material are identical to those of LZ bulk material, but the mechanical properties of the former are superior to those of the latter. Elemental analysis and X-ray diffraction indicate that compositional deviation of LZ coating can be optimized after doping by 3 wt.% Y2O3, Y2O3 acts as a dopant as well as a process regulator. The optimal composition of LZ3Y coating could be effectively achieved by the addition of excess Y2O3 into the ingot and by properly controlling the current of electron beam (i.e. similar to 650 mA).

Tm3+ and/or Dy3+ doped LaOCl nanocrystalline phosphors for field emission displays

Blue, yellow and white light emissive LaOCl:Tm3+, LaOCl:Dy3+ and LaOCl: Tm3+, Dy3+ nanocrystalline phosphors were synthesized through the Pechini-type sol-gel process. X-Ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL) and cathodoluminescence (CL) spectra were used to characterize the samples. Under UV radiation (229 nm) and low-voltage electron beam (0.5-5 kV) excitation, the Tm3+-doped LaOCl phosphor shows a very strong blue emission corresponding to the characteristic transitions of Tm3+ (D-1(2), (1)G(4) -> F-3(4), H-3(6)) with the strongest emission at 458 nm. The cathodoluminescent color of LaOCl:Tm3+ is blue to the naked eye with CIE coordinates of x = 0.1492, y = 0.0684. This phosphor has better CIE coordinates and higher emission intensity than the commercial product Y2SiO5:Ce3+.

One-Dimensional Ce3+- and/or Tb3+-Doped X-1-Y2SiO5 Nanofibers and Microbelts: Electrospinning Preparation and Luminescent Properties

One-dimensional X-1-Y2SiO5:Ce3+ and -Tb3+ nanofibers and quasi-one-dimensional X-1-Y2SiO5:Ce3+ and -Tb3+ microbelts have been prepared by a simple and cost-effective electrospinning process. X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry, transmission electron microscopy, high-resolution transmission electron microscopy, photoluminescence (PL), and cathodoluminescence spectra were used to characterize the samples. SEM results indicate that the as-prepared fibers and belts are smooth and uniform with a length of several tens to hundreds of micrometers, whose diameters decrease after being annealed at 1000 degrees C for 3 h. Under ultraviolet excitation and low-voltage electron beam excitation, the doped rare earth ions show their characteristic emission, that is, Ce3+ 5d-4f and Tb3+ D-5(4)-F-7(J) (J = 6, 5 4, 3) transitions, respectively.