Experimental Study of a Slot Antenna Excited by a TE011 Mode Coaxial Cavity

A slot antenna is developed to excite the high harmonic waveguide mode for generating large-area plasmas. This antenna consists of a TE₀₁₁ mode coaxial cavity with the axial slots positioned on equal interval on the inner wall. The waves radiated from those slots can excite the high harmonic mode in the central area. With the azimuthal symmetric wave field of the TE₀₁₁ mode, the number of the slots can be chosen to match the field pattern of the high harmonic mode. In this report, the dispersion relation of the coaxial waveguide, the coupling scheme and the mode competition of the cavity are studied. A method has been successfully developed to suppress the TE₁₂₁ mode which is the most competing mode to the TE₀₁₁ mode.     

High Frequency and High Mode Purity Operations of Gyrotron FU IVA

The cavity of the newest gyrotron, Gyrotron FU IVA in the high frequency series of Fukui University gyrotrons (the Gyrotron FU series) is designed to minimize the mode conversion from the main cavity mode to the higher modes. In this paper, the experimental results are compared with simulations for the complete gyrotron oscillator. The gyrotron has an additional advantage to cover the wide frequency range in submillimeter wave region.     

TE011 X-band niobium cavity with critical magnetic flux density higher than Bc1

Microwave critical magnetc flux densities B^ac_c of nearly 160 mT were obtained with a TE₀₁₁ X-band niobium cavity, these values being higher than the lower critical field B_c1 of the cavity material.     

Observation of Mode Patterns for High Purity Mode Operation in the Submillimeter Wave Gyrotron FU VA

Operation tests of a cavity designed for high purity mode operation of the submillimeter wave gyrotron FU VA has been carried out successfully. The observed emission patterns of several cavity modes appear very pure and are compared with calculated results. High purity mode operation has the advantage of making the conversion to Gaussian-like beams more efficient.     

Observation of Mode Patterns for High Purity Mode Operation in the Submillimeter Wave Gyrotron FU VA

Operation tests of a cavity designed for high purity mode operation of the submillimeter wave gyrotron FU VA has been carried out successfully. The observed emission patterns of several cavity modes appear very pure and are compared with calculated results. High purity mode operation has the advantage of making the conversion to Gaussian-like beams more efficient.     

Hybrid Optical Comb Filter with Multi-Port Fiber Coupler for DWDM Optical Network

Optical comb filters based on multi-port fused fiber couplers are proposed and numerically analyzed, 3-arm MZI composed by1fiber splitter and7×33×fiber coupler, and 2-stage cascaded FIR type MZI interleave filter.     

A Laser Source with High Spectral Purity for Simple Tunable Laser Raman Instrument

The authors present an external cavity diode laser with high spectral purity for tunable laser Raman spectroscopy. To achieve high spectral purity required for Raman spectroscopy, a laser cavity utilizing a volume phase holographic grating, which has very low stray light, is developed and the first-order diffracted beam from the grating is taken as the output. Raman signals can be obtained from common samples with only a commercial laser rejection filter, greatly simplifying a tunable Raman instrument.     

Numerical Study of Mode Competition in Coaxial Cavity Gyrotrons with Corrugated Insert

A time-dependent self-consistent multimode code which allows to model the interaction between the modes of a coaxial cavity gyrotron operating at the fundamental and/or at higher harmonics of the cyclotron frequency is presented. The Method of Moments (MoM) is used to obtain a rigorous solution of the eigenvalue problem for a coaxial waveguide with corrugated insert. It is shown that the use of the Surface Impedance Model for the calculation of modes operating at higher harmonics leads to incorrect results in high-power coaxial cavity gyrotrons. However, the numerical simulations based on the MoM agree well with the available experimental results.     

一种制备高纯度单分散金纳米棒的新方法

报道了一种温和的、低成本、有效制备高纯度单分散金纳米棒的新方法.采用种子生长法,在两种表面活性剂体系下液相合成金纳米棒,向粗产品中加入氯化钠溶液,通过提高反应液的离子强度,利用制备的金纳米棒与球形颗粒不同的静电作用将金纳米棒分离纯化.运用透射电子显微镜(TEM)和扫描电子显微镜(SEM)对金纳米棒的表面形貌进行表征.结果表明,在较短时间内可获得纯度达97％以上的金纳米棒,并初步探讨了提纯机理.     

基于PVK的高色纯度高稳定性有机电致红光器件

利用旋涂法和真空蒸镀法相结合的方法,根据能量空间传递的原理制备了PVK ∶ Ir(piq)₂(acac)体系的红色有机电致发光显示器件。器件的结构为ITO/CuPc/PVK ∶ Ir(piq)₂(acac)/BCP/Alq₃/LiF/Al。研究了不同主客体掺杂比对器件发光性能的影响,得到了高色纯度、单色性较好的红光器件。当Ir(piq)₂(acac)掺杂的质量比为1 ∶ 0.08时,器件的综合性能达到最佳,发光峰位于625 nm,CIE坐标为(x=0.66,y=0.33)。通过对各层厚度的合理选择,形成相对优化的微腔结构,充分利用其对光谱的窄化效应,使得器件的EL光谱的发射半峰全宽仅为55 nm,提高了器件的发光性能。器件光谱具有很好的单色性,色纯度达到98.2%。     

杂交稻种宜香725纯度的可见-近红外反射光谱鉴定

提出了一种基于可见-近红外光谱技术快速、无损鉴定杂交稻种纯度的新方法.以FieldSpec(R)3地物光谱仪采集纯度在90%～99%范围内的杂交稻种(宜香725)光谱数据90份,随机分成校正集(75份)和检验集(15份).根据其在380～2 400 nm的反射光谱,以偏最小二乘算法(PLS)建立了回归模型,并比较了不同光谱预处理方法对模型的影响.分析表明采用一阶导数结合标准归一化处理能最有效地提取光谱信息,此时PLS模型校正集决定系数与检验集决定系数分别为0.988 4与0.922 7,校正标准误差(SEC)与预测标准误差(SEP)分别为0.002 5与0.006 6.将经一阶导数结合标准归一化处理后的光谱进行PCA降维,以前20个主成份(含原始光谱86.09%的特征信息)为输入变量,建立杂交稻种纯度鉴定的BP-ANN模型.分析表明BP-ANN模型校正集决定系数与检验集决定系数分别为0.995 2与0.936 9,SEC与SEP分别为0.001 7与0.006 1,具有比PLS模型更高的精度.结果表明以可见-近红外技术进行杂交稻种纯度的快速、无损鉴定是可行的,且PCA结合BP-ANN是一种优选方法.     

A Novel Acoustic Emission Fiber Optic Sensor Based on a Single Mode Optical Fiber Coupler

This paper reports, for the first time, on the use of a fused-taper single mode optical fiber coupler as a sensing element for the detection of acoustic emission (AE) and ultrasound. When an acoustic wave impinges on the mode-coupling region of a coupler, the coupling coefficient is modulated via the photo-elastic effect. Therefore, the transfer function of the coupler is modulated by an acoustic wave. The sensitivity of the sensor at 140 kHz was approximately 5.2 mV/Pa and the noise floor was 1 Pa. The bandwidth of the sensor was up to several hundred kHz. This AE sensor exhibits significant advantage compared with interferometer-based AE sensors.     

A Novel Acoustic Emission Fiber Optic Sensor Based on a Single Mode Optical Fiber Coupler

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A Quasi-Optical System for Converting TE0n Mode Outputs of a Gyrotron into Gaussian Beams

In this paper we present a novel design of a quasi-optical system for conversion of gyrotron outputs into Gaussian-like beams. It consists of a quasi-optical antenna, two focusing mirrors and a filter which removes the side lobes of the beam. The system is appropriate as a transmission line for frequency tunable gyrotrons operating at TE_0n mode. As an illustration of our approach, we present results which demonstrate the applicability of the developed system for conversion of the radiation generated by the Gyrotron FU IVA. The examples include conversion of three TE_0n modes (TE₀₂, 223 GHz; TE₀₃, 323 GHz; TE₀₄, 423 GHz) into Gaussian- like beams.     

On the Radiochemical Purity of Elementary 35S with High Specific Activity

Radiochemical composition and chemical changes with increasing storage time of benzene solutions and of solid species of elementary ³⁵S with high specific activity are studied. The dependence of the stability on the specific activity and the radioactive concentration is shown and some tentative limits are given for permissible storage periods.     

高纯度烟草过氧化物酶(TOPⅠ)光谱特性研究

采用交换吸附脱色及柱层析新技术,成功地从烟叶中分离和纯化了一种烟草过氧化物酶同工酶(TOPⅠ),并对其进行了一系列光谱特性研究.基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)测得TOPⅠ分子量为21 888.5,等电点pI为3.5;氨基酸组成分析表明TOPⅠ为一含血红素的酸性蛋白酶.光谱学分析揭示,在402 nm处有一典型的Soret带,在498和636 nm处有特征吸收峰(α,β带),酸度和变性剂对TOPI在紫外可见区的特征吸收峰均产生一定的影响,TOP Ⅰ的荧光光谱测定结果说明TOPⅠ分子中含有Trp残基和Tyr残基以及其自身的独特的光谱学特性.     

高纯度烟草过氧化物酶（TOP I）光谱特性研究

采用交换吸附脱色及柱层析新技术，成功地从烟叶中分离和纯化了一种烟草过氧化物酶同工酶(TOP I)，并对其进行了一系列光谱特性研究。基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)测得TOP I分子量为21888．5，等电点pI为3．5；氨基酸组成分析表明TOP I为一含血红素的酸性蛋白酶。光谱学分析揭示，在402nm处有一典型的Soret带，在498和636nm处有特征吸收峰(α，β带)，酸度和变性剂对TOP I在紫外可见区的特征吸收峰均产生一定的影响，TOP I的荧光光谱测定结果说明TOP I分子中含有Trp残基和Tyr残基以及其自身的独特的光谱学特性。     

纳米金属肋混合表面等离子体波导模式特性分析

基于传统混合表面等离子体波导,提出了一种半导体纳米线和纳米金属肋混合的表面等离子体波导.采用有限元法对其模式特性进行了数值模拟,研究了该波导的有效折射率、传播损耗、归一化模场面积等特性随波导几何尺寸的变化规律,分析了该混合波导的增益阈值.结果表明:该波导具有较低的传播损耗和较强的光场限制能力,并且混合模式的最小模面积仅为0.001 52μm2.     

A long-pulse TE CO2 laser with a negative-branch unstable resonator

Summary A long-pulse (>3 μs) CO₂ laser has been built using a negative-branch, frequency-selective, unstable resonator. The results obtained with this device are shown. The authors of this paper have agreed to not receive the proofs for correction.