Further acceleration of MeV electrons by a relativistic laser pulse

With the development of photocathode rf electron gun, electrons with high-brightness and mono-energy can be obtained easily. By numerically solving the relativistic equations of motion of an electron generated from this facility in laser fields modelled by a circular polarized Gaussian laser pulse, we find the electron can obtain high energy gain from the laser pulse. The corresponding acceleration distance for this electron driven by the ascending part of the laser pulse is much longer than the Rayleigh length, and the light amplitude experienced on the electron is very weak when the laser pulse overtakes the electron. The electron is accelerated effectively and the deceleration can be neglected. For intensities around 10(19) W(.)mu m(2)/cm(2), an electron's energy gain near 0.1 GeV can be realized when its initial energy is 4.5 MeV, and the final velocity of the energetic electron is parallel with the propagation axis. The energy gain can be up to 1 GeV if the intensity is about 10(21) W(.)mu m(2)/cm(2). The final energy gain of the electron as a function of its initial conditions and the parameters of the laser beam has also been discussed.

脉宽压缩光栅用的多层膜设计和性能分析

应用于啁啾脉冲放大技术中的脉宽压缩光栅是基于多层膜作为基底，利用全息干涉技术和离子束技术刻蚀而成。脉宽压缩光栅的衍射效率和抗激光损伤阈值一方面依赖于光栅结构的设计，另一方面很大程度上取决于作为基底的多层膜的设计。给出了以413．1nm作为写入波长，1053nm作为使用波长的多层介质光栅膜的设计．样品在ZZS-800F、型真空镀膜机上采用电子束蒸发方式沉积而成，并给出了膜系结构对光学性能影响因素的详细分析，结果表明膜系H3L(H2L)^9H0．5L2．03H满足光栅膜的指标。给出了样品光学特性测试，其使用波

Graded index 532HR/1064HT filter by glancing angle deposition

Glancing angle deposition is a novel method to prepare graded index coatings. By using this method and physical vapour deposition, ZrO2 is used to engineer graded index filter on BK7 glass substrate. Controlling the deposition rate and the periodic oscillation of oblique angle of deposited material, a 10-period graded index ZrO2 filter with high reflection near 532 nm and high transmittance at wavelength 1064 nm is fabricated. The causes of difference between the theoretical and experimental results are discussed in detail. The material properties and electron gun nonlinearity are possibly the main origins of the difference, which result in the variations in both thickness control and deposition rate of the Elm material.

电子束蒸发镀膜速率控制

介绍了电子束蒸发镀膜速率控制的基本原理和方法,选取实际生产中大量使用且蒸发特性较难控制的SiO_2和HfO_2,对两者的电子束蒸发速率控制分别进行了实验研究。采用比例积分微分(PID)闭环反馈控制,通过Ziegler-Nichols工程经验公式进行原始参量整定,并在实验的基础上对控制器的原始参量进行调整以及对积分作用和微分作用进行分区处理,速率控制的实验结果表明,采用该参量整定方法并结合工艺流程的改进,能获得良好的速率控制。针对速率控制中存在的难点问题进行了分析,并提出改进措施:将速率控制和电子枪扫描控制相结合能进一步改善速率控制。

Analysis of equilateral triangle semiconductor microlasers with rough sidewalls

The mode frequencies and quality factors are calculated for the equilateral triangle semiconductor microlasers with sinusoidal and random Gaussian sidewalls. The results show that the modes can still have high Q-factors.

A semiconductor laser suitably fabricated by planar technology

The semiconductor microlasers with an equilateral triangle resonator which can be fabricated by dry etching technique from the laser wafer of the edge emitting laser, are analyzed by FDTD technique and rate equations. The results show that ETR microlaser is suitable to realize single mode operation. By connecting an output waveguide to one of the vertices of the ETR, we still can get the confined modes with high quality factors. The EM microlasers are potential light sources for photonic integrated circuits.

鞑靼荞麦（Fagopyrum tataricum Gaertn.）离体再生与遗传转化研究

鞑靼荞麦是我国特有的农业产品，具有抗寒耐旱特性和较高的营养保健功能。荞麦的开花习性及遗传特点导致其人工杂交授粉难以成功，这成为荞麦杂交育种难以获得突破的重要原因。因此利用转基因技术导入有益基因有可能成为荞麦遗传改良的新途径，而再生及转化体系的建立是开展转基因研究的基础。 本文研究了苗龄、外植体、几种激素配比对鞑靼荞麦（Fagopyrum tataricum Gaertn.）离体培养的影响，初步建立了鞑靼荞麦离体再生体系。结果表明，鞑靼荞麦离体再生的最佳取材时间为苗龄6-8d；诱导愈伤组织的最适培养基为MS＋2.0 mg/L 2,4-D＋1.5 mg/L 6-BA，子叶诱愈率达75％左右，下胚轴的可高达86.62％；愈伤组织分化的最适培养基为MS 0.1mg/L IAA＋2.0mg/L 6-BA＋1.0 mg/L KT＋0.5mg/L TDZ，下胚轴的分化率可达9.52%。下胚轴的诱愈率与分化率均高于子叶，更适于离体再生培养。培养基中加入AgNO3后，能有效降低褐化率。生根最适培养基为含有0.5mg/L NAA的1/2MS培养基，生根率在50％左右。TDZ在诱导鞑靼荞麦的愈伤组织分化出芽的过程中起到明显的促进作用，可提高分化率约20%。 在上述研究基础上，本文还对鞑靼荞麦的遗传转化体系进行了探索性研究。分别利用根癌农杆菌（Agrobacterium tumefaciens）介导法和微粒轰击法（基因枪法）对黑水苦荞下胚轴进行遗传转化。 在农杆菌介导的方法中，携带有质粒pCAMBIA2301的农杆菌菌株EHA105用于转化。载体质粒pCAMBIA2301包含有gus和npt-II 基因, 并受35s启动子驱动。研究结果表明，在侵染方式选择上，浸泡方式比吸打方式更有效，根癌农杆菌侵染的较适浓度为OD600＝0.5，共培养3天，恢复培养7天，能检测到gus基因的表达。 基因枪法使用质粒pBI121，同样包含有gus和npt-II基因, 并受CaMV35s 启动子驱动。轰击距离为9cm较合适，甘露醇前处理在本研究中未表现出明显优势。 两种转化方法比较，基因枪法比农杆菌介导法更快速有效。 本研究为进一步的遗传操作研究打下基础。 Tartary buckwheat (Fagopyrum tataricum Gaertn.), the traditional and unique agricultural product of China, is a kind of crop with strong drought and cold tolerance, abundant nutrition and high medical value. Artificial hybridization is hard in buckwheat because of its flowering habits and genetic characteristics, which leads to no breakthrough in tartary buckwheat breeding. However, biotechnological approaches, especially genetic transformation for the direct introduction of good genes into tartary buckwheat for quality improvement, hold great promise. In this study, we established tartary buckwheat regeneration system in vitro. It is the foundation for genetic manipulation of this crop. The effects of seedling age, hypocotyl and cotyledon as explants, and proportions of several growth regulators were tested in tissue culture of tartary buckwheat for establishing its in vitro regeneration system. The results showed that the best seedling age for callus induction was 6 to 8 days. On the MS medium containing 2.0mg/L 2, 4-D and 1.5mg/L 6-BA, the induction rate of callus from hypocotyls was up to 86.62%, while from cotyledons was about 75％. The suitable shooting medium was the MS medium+0.1mg/L IAA+2.0mg/L 6-BA+1.0 mg/L KT+0.5mg/L TDZ, and the shooting rate from hypocotyls was 9.52%. The callus induction and shooting rates were higher from hypocotyls than from cotyledons. Browning reduced when the medium mixed with AgNO3. Half strength MS supplemented with 0.5mg/L NAA was the best for rooting, the rate was around 50% after 30 days culture. TDZ can accelerate the shoot differentiation distinctively, and it could improve the shooting rate nearly 20%. On the base of above, the explorative research of the genetic transformation in tartary buckwheat was done. In the study, hypocotyls from Heishui tartary buckwheat were transformed by Agrobacterium-mediated method and microprojectile bombardment method (gene-gun), comparatively. In Agrobacterium-mediated method, a disarmed Agrobacterium tumefaciens strain EHA105 harboring plasmid pCAMBIA2301 was used. The vector pCAMBIA2301 contains gus and npt-II genes, driven by CaMV35s promoter. The results showed that the appropriate concentration of Agrobacterium tumefaciens for infecting was OD600＝0.5, and co-culture time was 3d. Seven days later after coculture, GUS expression could be tested. In particle bombardment transformation, plasmid pBI121 was used. pBI121 also contains gus and npt-II genes, driven by 35s promoter. Hypocotyls pretreated with mannitol, no effect was observed, and the suitable distance of bombardment is 9cm. Comparing with Agrobacterium-mediated method, gene-gun method is more convenient and effective. All above results could be a basic work for further study in tartary buckwheat transformation.

并行设备总线嵌入式控制系统设计

为了对物理实验装置的远程监控和访问,将采用32位内核芯片技术结合CPLD逻辑时序编程来设计3U VME设备总线系统。S3C4510B是三星公司针对网络应用而设计的CPU,本身带有100Mbps网络控制器,而由于Clinux系统拥有完善的TCP/IP协议,因此二者的结合为用户提供了强大的网络服务功能。该系统利用嵌入式网络和并行总线技术可稳定可靠地实现数据的快速获取与给定。

Development of external electron-beam enhancement of the Penning ionization gauge ion source

To study the injection of additional electrons from an external electron gun into the plasma of a Penning ionization gauge (PIG) ion source, a test bench for the external electron-beam enhancement of the PIG (E-PIG) ion source was set up. A source magnet assembly was built to satisfy the request for magnetic field configuration of the E-PIG ion source. Numerical calculations have been done to optimize the magnetic field configuration so as to fit the primary electrons to be fed into the PIG discharge chamber along the spreading magnetic field lines. Many possible methods for improving the performance and stability of the PIG ion source have been used in the E-PIG ion source, including the use of multicrystal LaB6 cathode and optimized axial magnetic field. This article presents a detailed design of the E-PIG ion source. Substantial enhancement of ion charge state is expected to be observed which demonstrates that the E-PIG is a viable alternative to other much more costly and difficult to operate devices for the production of intense ion beams of higher charge state.

谐振式电子加速器电子枪注入控制系统

电子加速器作为一种工业化设备已经在各个领域得到了广泛的应用，它的内部控制电路工作在高电压环境中，尤其是高电压端存在的各种干扰对其稳定性影响很大，使得高压端的控制显得很困难，由于以往使用的高压端控制电路常常发生损坏，因此本文就高压端控制进行了讨论，并从原理和元器件设计方面考虑来解决这些问题。本文对大功率谐振式电子加速器的用途、工作原理以及总体结构做了简要的介绍，同时主要阐述了电子加速器电子枪注入控制系统的原理设计、总体结构以及实验结果。本文对以往使用的控制回路在高压端工作时其存在的问题进行了分析，比较了两种方案的优缺点，主要从电路的抗干扰和抗电流冲击以及稳定性出发对电路的各个部分进行了合理的设计，重点对组成电路的各个单元进行了详细的原理介绍和设计计算，而且对整个系统进行了SIM 99仿真，得到了合理的结果，与实验过程中所测数据完全一致。通过对电路的实际调试和分析可以看出该系统比旧系统在抗干扰和可靠性方面有大幅度的提高

长灯丝电子枪的设计与控制

近年来，辐照加工技术及产品已经在农业、材料、电工、电子、医疗、食品等行业得到应用和发展，与相关行业结合为推动传统产业的技术改造方面发挥了独特的作用。为了适应生产的需要，本文在实验室设备的基础上对长灯丝电子枪的设计与控制进行了分析和尝试。加速器的外部结构是加速器在正常运行的基本保证，本文在对击穿电场计算的基础上给出了加速器外部结构设计的尺寸，对于影响束流纵向分布的主要因素—长灯丝的下垂，本文给出了其挠度的计算公式，并根据灯丝的物理特性和发射电子的冷端效应对其约束条件进行了分析，给出了灯丝约束的基本模型。栅压值的大小与栅极缝的大小是束流引出的重要环节，本文通过对简化模型的束流光学计算，分析了束流引出大小的原因。通过对被控对象—束流的分析，我们采用了传统的PID与微分先行控制器结合的控制算法对束流进行控制，在实验室条件得以实现。并对束流传动装置在辐照剂量的限制下实现了动态控制。控制软件设计主要讨论了Windows操作系统的特点及在其下实现实时性的方法，采用面向对象的编程方法提高了程序的可读性，可移植性和可维护性。

电子帘加速器电子枪物理设计

电子帘加速器是一种七十年代产生的低能大功率工业辐照用电子加速器，现已广泛应用到涂层固化、像胶硫化、杀菌消毒等领域。本文对电子帘加速导电子枪的束流传输待性进行了分析。 作为对电子帘加速器设计理论的一种探索，本文首先由负载束流强度佑计灯丝温度，然后根据反射极的电容器简化模型导出了悬浮电位随时间的演化方程，数值计算显示其电位值在48小时内交化很小。对于栅极缝的透镜效应，本文由一定的近似导出了栅极缝附近的电位分布解析表达式，从而计算出电子束从电子枪到加速腔的轨迹。对于影响束流纵向分布的主要因素——长灯丝的下垂，本文给出了其挠度公式并提出了一种理想的边界约束模型，以减小灯丝的挠度。 根据上途理论及一些假设，本文改交电子枪各参数计算了26种情况的束流包络及横向分布，从负载部分的大小和均匀性两方面比较选择出一种较理想的电子枪结构．同时对原电子枪进行了校核，从理论上解释了其实验中出现的问题‘ 实脸测试表明新电子枪的束流纵向均匀度为士10％。均匀性及加热比功率等性能均优于原电子枪。 最后，对电子帘加速器毛子枪将来的发展的几个问题给出了一些建议。

Synthesis and spectral properties of lutetium-doped CeF3 nanoparticles

CeF3 and lutetium-doped CeF3 nanoparticles with the dopant concentration of 17, 25, 30, 42 and 50 mol% (molar ratio, Lu/Ce) were synthesized. XRD patterns were indexed to a pure CeF3 hexagonal phase even under the dopant concentration of 50 mol%. Environmental scanning electron microscopy-field emission gun (ESEM-FEG) was used to characterize the morphology of the final products. From the luminescence spectra of the products, we can get a broad emission ranging from 290 to 400 nm with peak at 325 nm. Lutetium-doping increases the luminescence intensity. We got. the most intense luminescence at the dopant concentration of 30 mol%.