Laterally Electrostatically Driven Poly 3C-SiC Folded-Beam Resonant Microstructures

Micromachined comb-drive electrostatic resonators with folded-cantilever beams were designed and fabricated. A combination of Rayleigh＇s method and finite-element analysis was used to calculate the resonant frequency drift as we adjusted the device geometry and material parameters. Three micromachined lateral resonant resonators with different beam widths were fabricated. Their resonant frequencies were experimentally measured to be 64.5,147.2, and 255.5kHz, respectively, which are in good agreement with the simulated resonant frequency. It is shown that an improved frequency performance could be obtained on the poly 3C-SiC based device structural material systems with high Young＇s modulus.

Strained MQW electro-absorption modulators with high extinction ratio and low capacitance

We fabricate an electro-absorption modulator for optical network system using a new strategy, the improved modulation properties of the strained InGaAs/InAlAs MQW show it's polarization independent, high extinction ratio (> 40dB) and low capacitance (C <0.6pF) which can achieve an ultra-high frequency(> 10GHz). The device is be used in 10Gbps optical time division multiplex (OTDM) system as a signal generator.

中国裂叶苔科植物的研究-分类、区系和生态

裂叶苔科（Lophoziaceae）是叶苔目植物中的一个大科，其植物体形态变化较大，分类较为困难。中国在裂计佩一苔科下已记录的植物有23属、106种、2变种和2变形。本论文在大量文献考证和对国内外3000余份标本深入研究基础上，对中国裂仆佩一苔科进行了较系统全面的分类修订，记录了中国裂价卜苔科植物共有11属45种3变种1变形，提供了种属形态特征描述和41幅图版。发现中国新记录2种1变型：异瓣裂叶苔（Lophozia diversiloba Hatt），毛口挺叶苔（Anastrophyllum piligerm (Nees.) Steph.）和密叶三瓣苔小叶变形（Tritomaria quinquedentata fo. gracilis (Jens.) Schust.）；新组合名1个：小挺叶苔尖变种（Anastrophyllum minutum (Schreb. in Cranz.) Schust var. acuminatum (Horik.) Cao & Sun comb. nov.），还有省区新分布记录16个。采用聚类分析方法分析了裂叶苔科种属间的关系，结果支持广义裂汗卜苔属和挺口一卜苔属的概念。 区系成分的分析研究表明：中国裂计佩一苔科植物的地理成分主要以泛北极分布类型为主，占79.6%.东北地区、秦岭地区、西南地区和台湾省为我国裂p_佩一苔科植物种类最丰富的地区。在国内首次开展了苔类专科的生态学研究，并采用CCA方法对结果进行分析。研究表明：裂叶苔科植物在长白山分布上表现出明显的垂直地带性，可分为三类：（1)分布在2000米以上苔原带的种类，主要有小挺叶苔A. minutum、石生挺叶苔A. saxicola、密叶三瓣苔T. quinquedentata、高山裂叶苔L. sudetica，圆叶裂叶L. wenzelii；（2）分布在1730米到2000米苔岳桦林带的种类，主要有：方叶无褶苔L. bantriensis，细裂瓣苔B. barbata，阔瓣裂叶苔L. excisa；（3）分布在1150-1730米以下暗针叶林的种类，主要有：三瓣苔T. exsecta，多角胞三瓣苔T. exsectiformis、囊苞裂叶苔L. ventricosa，秃瓣裂叶苔L. obtusa和倾立裂叶苔L. ascendens。影响裂叶苔科植物分布的主要坏境因子是海拔高度。 对处于不同纬度三个地区的同种裂叶苔科植物的比较分析说明：随纬度的升高其分布的海拔高度逐步降低。

Generation of 10 GHz, 1.9 ps optical pulse train using semiconductor optical amplifier and silica-based highly nonlinear fiber

We propose a simple approach to generate a high quality 10 GHz 1.9 ps optical pulse train using a semiconductor optical amplifier and silica-based highly nonlinear fiber. An optical pulse generator based on our proposed scheme is easy to set up with commercially available optical components. A 10 GHz, 1.9 ps optical pulse train is obtained with timing jitter as low as 60 fs over the frequency range 10 Hz-1 MHz. With a wavelength tunable CW laser, a wide wavelength tunable span can be achieved over the entire C band. The proposed optical pulse generator also can operate at different repetition rates from 3 to 10 GHz.

冷却储存实验环功率源的设计与计算

RF system of HIRFL-CSRe(cooling storage experimental ring)was designed by ourselves and manufactured domestically,which operates in the frequency range of 0.5~2.0 MHz at first and second harmonic modes.Based on detailed engineering calculation,the design of RF generator was completed.It will work not only in CW mode but also in the mode of ramping pulse modulation,and the maximum power is up to 70 kW.It satisfies the requirement of 10 kV maximum deceleration voltage to capture the irradiative beam and decel...中文摘要：对兰州重离子加速器冷却储存环实验环(CSRe)的高频系统功率源的设计作了详细的工程计算,工作频率范围为0.5～2.0MHz,工作于基波及二次谐波模式,发射机不仅能工作于点频连续波模式,而且还可以工作在扫频调制模式,输出最大功率达到70kW。满足最高加速或减速电压10kV的设计要求,能够用于捕获放射性次级束并将束流的能量从400MeV/u减速到30MeV/u。

RF system design and measurement of HIRFL-CSRe

An RF system for the CSRe (cooling storage experimental ring) is designed and manufactured domestically. The present paper mainly describes the RF system design in five main sections: ferrite ring, RF cavity, RF generator, low level system and cavity cooling. The cavity is based on a type of coaxial resonator which is shorted at the end with one gap and loaded with domestic ferrite rings. The RF generator is designed in the push-pull mode and the low level control system is based on a DSP+FGPA+DDS+USB inter...

Experimental results of helicon sources

Helicon plasma source is known as an efficient generator of uniform and high density plasma. A helicon plasma source was developed for the investigation of plasma striping and plasma lens at the Institute of Modern Physics, CAS. In this paper, the characteristics of helicon plasma have been studied by using Langmuir four-probe and a high plasma density up to 3.9×1013 /cm3 has been achieved with the Nagoya type III antenna. In the experiment, several important phenomena have been found: (1) for a given magnetic induction intensity, the plasma density became greater with the increase of RF power; (2) the helicon mode appeared at the RF power between 300 W and 400 W; (3) the plasma density gradually tended to saturation as the RF power increased to the higher power; (4) a higher plasma density can be obtained by a good matching between the RF power and the magnetic field distribution. The key issue is how to optimize the matching between the RF power and the magnetic field. Moreover, some tests on the extraction of ion beam were performed, and the preliminary results were given. The problems which existed in the helicon ion source will be discussed and the increase in beam density will be expected by extraction system optimum.

Single-electron capture in keV Ar15+...18++He collisions

Single-electron capture in 14 keV q(-1) Ar15+...18++He collisions is investigated both experimentally and theoretically. Partial cross sections and projectile scattering angle dependencies have been deduced from the target ion recoil momenta measured by the COLTRIMS technique. The comparison with close-coupling results obtained from a two-centre extension of the basis generator method yields good overall agreement, demonstrating the applicability of close-coupling calculations to collision systems involving highly charged ions in charge states up to 18+.

BRST quantization and canonical Ward identity of the supersymmetric electromagnetic interaction system

According to the method of path integral quantization for the canonical constrained system in Becchi-Rouet-Stora-Tyutin scheme, the supersymmetric electromagnetic interaction system was quantized. Both the Hamiltonian of the supersymmetric electromagnetic interaction system in phase space and the quantization procedure were simplified. The BRST generator was constructed, and the BRST transformations of supersymmetric fields were gotten; the effective action was calculated, and the generating functional for the Green function was achieved; also, the gauge generator was constructed, and the gauge transformation of the system was obtained. Finally, the Ward-Takahashi identities based on the canonical Noether theorem were calculated, and two relations between proper vertices and propagators were obtained.

BRST invariant theory of a generalized 1+1 Dimensional nonlinear sigma model with topological term

We give a generalized Lagrangian density of 1 + 1 Dimensional O( 3) nonlinear sigma model with subsidiary constraints, different Lagrange multiplier fields and topological term, find a lost intrinsic constraint condition, convert the subsidiary constraints into inner constraints in the nonlinear sigma model, give the example of not introducing the lost constraint. N = 0, by comparing the example with the case of introducing the lost constraint, we obtain that when not introducing the lost constraint, one has to obtain a lot of various non-intrinsic constraints. We further deduce the gauge generator, give general BRST transformation of the model under the general conditions. It is discovered that there exists a gauge parameter beta originating from the freedom degree of BRST transformation in a general O( 3) nonlinear sigma model, and we gain the general commutation relations of ghost field.

The study of helicon plasma source

Helicon plasma source is known as efficient generator of uniform and high density plasma. A helicon plasma source was developed for investigation of plasma neutralization and plasma lens in the Institute of Modern Physics in China. In this paper, the characteristics of helicon plasma have been studied by using Langmuir four-probe and a high argon plasma density up to 3.9x10(13) cm(-3) have been achieved with the Nagoya type III antenna at the conditions of the magnetic intensity of 200 G, working gas pressure of 2.8x10(-3) Pa, and rf power of 1200 W with a frequency of 27.12 MHz. In the experiment, the important phenomena have been found: for a given magnetic induction intensity, the plasma density became greater with the increase in rf power and tended to saturation, and the helicon mode appeared at the rf power between 200 and 400 W.

New development of advanced superconducting electron cyclotron resonance ion source SECRAL (invited)

Superconducting electron cyclotron resonance ion source with advance design in Lanzhou (SECRAL) is an 18-28 GHz fully superconducting electron cyclotron resonance (ECR) ion source dedicated for highly charged heavy ion beam production. SECRAL, with an innovative superconducting magnet structure of solenoid-inside-sextupole and at lower frequency and lower rf power operation, may open a new way for developing compact and reliable high performance superconducting ECR ion source. One of the recent highlights achieved at SECRAL is that some new record beam currents for very high charge states were produced by 18 GHz or 18+14.5 GHz double frequency heating, such as 1 e mu A of Xe-129(43+), 22 e mu A of Bi-209(41+), and 1.5 e mu A of Bi-209(50+). To further enhance the performance of SECRAL, a 24 GHz/7 kW gyrotron microwave generator was installed and SECRAL was tested at 24 GHz. Some promising and exciting results at 24 GHz with new record highly charged ion beam intensities were produced, such as 455 e mu A of Xe-129(27+) and 152 e mu A of Xe-129(30+), although the commissioning time was limited within 3-4 weeks and rf power only 3-4 kW. Bremsstrahlung measurements at 24 GHz show that x-ray is much stronger with higher rf frequency, higher rf power. and higher minimum mirror magnetic field (minimum B). Preliminary emittance measurements indicate that SECRAL emittance at 24 GHz is slightly higher that at 18 GHz. SECRAL has been put into routine operation at 18 GHz for heavy ion research facility in Lanzhou (HIRFL) accelerator complex since May 2007. The total operation beam time from SECRAL for HIRFL accelerator has been more than 2000 h, and Xe-129(27+), Kr-78(19+), Bi-209(31+), and Ni-58(19+) beams were delivered. All of these new developments, the latest results, and long-term operation for the accelerator have again demonstrated that SECRAL is one of the best in the performance of ECR ion source for highly charged heavy ion beam production. Finally the future development of SECRAL will be presented.

Effect of sodium alginate concentration on membrane strength and permeating property of poly-l-arginine group microcapsule

A novel poly-l-arginine microcapsule was prepared due to its nutritional function and pharmacological efficacy. A high-voltage electrostatic droplet generator was used to make uniform microcapsules. The results show that the membrane strength and permeating property are both remarkably affected with the changes of sodium alginate concentration. With the sodium alginate concentration increasing, gel beads sizes increase from 233 mum to 350 mum, release ratio is also higher at the same time, but the membrane strength decreases.