Design and optimization of an electromagnet undulator

In this paper we discuss the design and optimization of an electromagnet undulator. A short period electromagnet undulator has been reported and used for free electron laser experiment under the approximation of infinite permeability of the lamination core. Here we remove this approximation and present analytical expressions for an alternate design concept on the electromagnet undulator.     

双向聚焦电磁铁摇摆器磁场的数值模拟

 应用磁矢量势公式导出了螺线圈绕组的磁场计算公式，应用标量磁势并对电磁铁作局部均匀磁化近似，给出了电磁铁摇摆器磁场的积分方程式和相应的耦合系数。通过求解积分方程得到了摇摆器磁场的空间分布及摇摆器两端非均匀区的磁场分布。本方法可以为双向聚焦电磁铁摇摆器的设计提供参考数据。     

100 GHz mixer vertically integrated (stacked) SIS junction array

A Vertically Integrated Array (stacked array) of single windowSIS junctions (VIA SIS), based on a stacked five layer structure of Nb-AlO_x-Nb-AlO_x-Nb, has been fabricated and tested in a quasi optical mixer configuration at 106 GHz. This particular VIA SIS design has two stacked junctions fabricated by standard tri-layer process employing photolithography, reactive ion and wet etching processes. A simple expression for calculating the specific capacitance of single and arrayed SIS junctions is suggested. Due to the absence of interconnection leads between the individual junctions and reduced overall capacitance, compared to a single SIS junction, has the VIA SIS good future prospects for use in submillimeter wave SIS mixers The VIA SIS may be regarded as a lumped rather than a distributed structure at least up to the gap frequency at 730 GHz for Nb. DC-IV measurements show high quality of the Individual SIS junctions and good reproducibility of the array parameters over the substrate area. The first VIA SIS mixer experiments yielded a receiver noise temperature of 95 K (DSB) at a LO frequency of 106 GHz.     

Bench-Top Type In Vivo EPR Spectrometer for Estimating the Renal Reducing Ability of a Rat

A main electromagnet optimized for electron paramagnetic resonance (EPR) measurements of rats by using a surface loop resonator with a loop diameter of 10?mm was designed. The fabricated main electromagnet was ca. 420?mm in diameter, ca. 240?mm in width, and ca. 60?kg in weight. When a static magnetic field of 25?mT was generated at the center of the main electromagnet, its deviation in a sphere space with a diameter of 10?mm was <0.02?mT. In this condition, the temperature elevation on the surface of the magnet was negligible for the measurement time assumed for in vivo study. Using this magnet, a bench-top type in vivo EPR spectrometer could be obtained, which made it possible to perform EPR measurements for estimating the renal reducing ability of a rat.     

A Multibeam SIS Mixer Module for a Focal Plane Array Receiver

The integration of many receiver units into a receiver array is a common method of improvement of imaging systems. This approach, well known in the mm band for Schottky mixer arrays, has not so far been developed for Superconductor - Insulator - Superconductor (SIS) junction mixers, which give the best sensitivity in the short mm wave range and in the submm range.We demonstrate for the first time a practical low noise multibeam receiver module using SIS mixer technology. The basis for the integration of several SIS mixers with a common local oscillator source is given by the saturation of the SIS receiver noise dependence upon local oscillator power. The module comprises three identical SIS mixers integrated with a common local oscillator, coupled through a three branch waveguide directional coupler. The multibeam module has been developed for a focal plane array receiver of the 30 meter radio telescope of the Institut de Radioastronomie Millimétrique (IRAM).     

Surface wetting behavior of the poly(styrene-b-isoprene-b-styrene) triblock copolymer with different chemical structures of the polyisoprene block chain

The relationship between the chemical structure of a block copolymer and its surface structure and properties is very important for the careful design of its outer surface layer. For this paper, a series of poly(styrene-b-isoprene-b-styrene) triblock copolymers (SIS), with different chemical structures in the polyisoprene block chain, were synthesized by anionic polymerization and their dynamic wetting behaviors were investigated. The dynamic contact angles of the polyisoprene homopolymer (PI) and the SIS were almost the same when the PI and the corresponding block in the SIS had similar chemical structures. The receding contact angle (θ_r) of SIS depended on the microstructure of the PI block chain, however, the advancing contact angles (θ_a) were almost the same regardless of the PI’s chemical structures. The receding contact angle (θ_r) of SIS containing 3,4-PI was far higher than that of SIS with 1,4-PI. Meanwhile, it gradually approached that of SIS with 1,4-PI as the of 3,4-PI content decreased or as the local temperature increased. Contact angle measurement is one of the most sensitive methods for providing information on the outer few angstroms of a polymer’s surface. Therefore, by designing SIS with different chemical structures in the PI block, it was confirmed that the properties and structure of the outermost layer of the SIS were controlled primarily by the PI block’s chemical structure. This demonstrates the possibility to modulate the surface structure and properties of SIS by adjusting the chemical structure of polyisoprene segment.     

Low noise completely quasioptical SIS receiver for radioastronomy at 115 GHZ

Completely quasioptical heterodyne SIS receiver for radioastronomical applications at 115 GHz was designed and tested. Gaussian beam two lens input guide system and open structure SIS mixer with immersion lens were used. Integrated quasioptical structure consists of planar equiangular spiral antenna and superconductor—insulator—superconductor (SIS) tunnel junction as a mixing element connected to the antenna via microstrip impedance transformer. The best SIS mixer noise temperature at hot input and for heterodyne frequency 109.8 GHz with IF central frequency 1.4 GHz (DSB) was 28±7 K at the first quasiparticle step and 8±6 K at the second step.     

A Novel LO Power Injection Method for SIS Mixers

We propose a novel LO power injection method developed for SIS mixers in this paper. Based on the feature of extremely small LO power requirements of SIS quantum mixing, the new method fulfills SIS pumping through a DC/IF route based built-in LO path, which is composed of an additional LO waveguide and the existing microstrip choke filter on the junction substrate. With the new method, traditional external LO diplexers(e.g., crossguide-couplers or beamsplitters) become unnecessary, resulting in a lower loss, compact, and stable receiver system. Experiments at 110- and 230 GHz bands have shown that the present method is efficient in coupling sufficient pumping power to SIS junctions from general LO sources, and the receiver sensitivities have a further improvement of about 10 K. We expect this method is also able to be applied into submillimeter wave band for SIS mixers.     

Formation of the Magnetic Field in the CC 30/15 Isochronous Cyclotron

Physics of Particles and Nuclei Letters - Design features of the electromagnet of the CC 30/15 isochronous cyclotron using mathematical modeling methods are presented. The electromagnet of shielded...     

Evaluation of protein quantification using standard peptides containing single conservative amino acid replacements

Structural analogs are evaluated as peptide internal standards for protein quantification with liquid chromatography-multiple reaction monitoring mass spectrometry (LC-MRM); specifically, single conservative amino acid replacements (SCAR) are performed to create tagged standards that differ by the addition or subtraction of a single methylene group in one amino acid side chain. Because the performance of stable isotope-labeled standards (SIS) has been shown to be superior to structural analogs, differences in both development and quantitative performance between assays based on SIS and SCAR peptides are explored. To establish an assay using the structural analogs, analysis of endogenous, SCAR and SIS peptides was performed to examine their ion signal, fragmentation patterns and response in LC-MRM. Performance of SCAR and SIS peptides was compared for quantification of epidermal growth factor receptor from lung cancer cell lysates and immunoglobulin M in the serum of multiple myeloma patients.     

Electrospinning and Mechanical Properties of Polystyrene and Styrene-Isoprene-Styrene Block Copolymer Blend Nanofibres

Electrospinning of polystyrene (PS) and styrene–isoprene–styrene block copolymer (SIS) blends with different composition weight ratios was carried out with a mixed solvent, tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) (80/20, v/v). Electrospun PS/SIS blend fibers were characterized using scanning electron microscopy. The results indicated that the presence of DMF resulted in a beneficial effect on fiber formation and greater electrospinnability of as-spun fibers. Furthermore, the morphological structure and diameters of as-spun fibers from PS and SIS blends were affected by the composition weight ratio and the solution properties. The fibers from 10 wt% solution exhibited the best mechanical properties compared to the fibers from other concentrations for the same composition, and increasing the SIS content one observes a vanishing of PS-related properties, while SIS-related properties emerges.     

Negative-index dispersion and accidental mode degeneracy in an asymmetric spoof-insulator-spoof waveguide

It has been recently demonstrated that negative-index dispersion and mode degeneracy can be achieved by manipulating a spoof-insulator-spoof(SIS) waveguide. In this paper, we propose a new SIS waveguide, which is composed of two spoof surface plasmon polaritons(SSPPs) waveguides drilled with periodic rhomboidal grooves. Both the symmetric and asymmetric cases are investigated. Our simulation results show that the asymmetric SIS waveguides are more significant.By tailoring the tilt of the rhomboidal grooves, the negative-index dispersion can be achieved and the microwave band gap(MBG) can be effectively modulated. At a critical tilt, there appears an accidental mode degeneracy at the edge of the first Brillouin zone. The excitation and propagation of the two coupled modes sustained by the asymmetric SIS waveguides are also demonstrated.     

An off-axis 50-period electromagnet wiggler for millimeter-wavefree-electron laser experiment

An off-axis 50-period planar, short-wavelength (~10 mm) electromagnet wiggler is developed and characterized for millimeter-wave generation using a sheet electron beam in a free-electron laser experiment. Three-dimensional (3-D) magnetic field measurements of the electromagnet wiggler have been carried out. The measured wiggler magnetic field is 0.16 G/A ±3% while the mean value of wiggler wavelength is 0.998±3% cm. Due to off-axis arrangement of poles, there is a magnetic mirror field in the X direction, to confine the sheet beam     

负载弦之演示教具

介绍一自制的负载弦教具，5颗沿铀向充磁的圆柱状钐钴磁铁穿在细钓鱼线上，作为负载弦之负载质点，再以可调频率的交流电磁化马蹄形电磁铁，使得马蹄形电磁铁对圆柱状钐钴磁铁施与周期性的引力及斥力，启动负载弦的各个简正模式．此自制的负载弦教具可定量演示教科书中理论计算的结果．     

Overhauser DNP and EPR in a Mobile Setup: Influence of Magnetic Field Inhomogeneity

Power-dependent Overhauser dynamic nuclear polarization (DNP) enhancements and continuous-wave electron paramagnetic resonance (EPR) spectra of nitroxide radicals were measured in the magnetic field of a mobile Halbach-array permanent magnet and compared with results from a commercially available electromagnet. DNP saturation factors for varying microwave power were obtained from both measurement series and used to investigate how the increased magnetic field inhomogeneity present in the Halbach magnet affects the saturation efficiency. An EPR detection system was designed to allow continuous-wave EPR measurements at microwave power up to 20?W. Our results show that despite the lower magnetic field homogeneity, a Halbach-array magnet can be used for EPR and DNP-enhanced nuclear magnetic resonance of high quality providing almost the same performance as a more homogeneous electromagnet.     

Analysis of undulator radiation with an electromagnet undulator

In this paper we discuss the theory of undulator radiation in an electromagnet undulator. We discuss the spectral properties of undulator radiation when electrons are injected off the undulator axis. This paper highlights the distinctive features of the radiation spectrum from electromagnet undulators, as compared to PPM undulators.     

Characterization of Nb-Based Superconducting Microstrip Lines Around the Gap Frequency

Submillimter-wave SIS (superconductor-insulator-superconductor) mixers usually adopt SIS junctions associated with an integrated tuning circuit, which tunes out the junction's geometric capacitance and is typically an inductive thin-film superconducting microstrip line. This paper mainly investigates the characteristic of Nb-based superconducting microstrip lines around the junction's gap frequency, at which the surface resistance of Nb films becomes considerable, and its effect on the performance of SIS mixers.     

Noise Stability of SIS Receivers

There is a strong interest in the submillimeter astronomy community to increase the IF bandwidth of SIS receivers in order to better facilitate broad spectral linewidth and continuum observations of extragalactic sources. However, with an increase in receiver IF bandwidth there is a decrease in the mixer stability. This in turn effects the integration efficiency and quality of the measurement. In order to better understand the noise mechanisms responsible for reducing the receiver stability, we employed a technique first described by D.W. Allan and later elaborated upon by Schieder et al. In this paper we address a variety of factors that degrade the noise stability of SIS receivers. The goal of this exercise is to make recommendations aimed at maximizing SIS receiver stability.     

An Integrated Sideband-Separating SIS Mixer Based on Waveguide Split Block for 100 GHz Band with 4.0–8.0 GHz IF

We have developed an integrated sideband-separating SIS mixer for the 100 GHz band based on the waveguide split block. The measured receiver noise temperatures with 4.0–8.0 GHz IF are less than 60 K in the LO frequency range of 90–110 GHz, and a minimum value of around 45 K is achieved at 100 GHz. The image rejection ratios are more than 10 dB in the frequency range of 90–110 GHz. We have installed the sideband-separating SIS mixer into an atmospheric ozone-measuring system at Osaka Prefecture University and successfully observed an ozone spectrum at 110 GHz in SSB mode. This experimental result indicates that the sideband-separating SIS mixer is very useful for astronomical observation as well as atmospheric observation.     

300GHz超导SIS接收机系统的设计与构建

超导SIS(Superconductor-Insulator-Superconductor)混频技术是新兴的低噪声检测技术.其卓越的低噪声性能已使其成为毫米波和亚毫米波频段灵敏度最高的谱线接收设备,接收机的自动控制和稳定性有更高的要求,研制能够长期稳定工作的接收机有很重要的意义.本文主要讨论了我们自行研究设计工作在4K温度,准光学系统的毫米波超导SIS接收机的组成部件,根据我们制备的超导SIS隧道结器件的特性指标,计算设计了300GHz波段的超导接收机天线和结的集成芯片.