A new structure of superconducting magnetic system for 50 GHz operations (invited)

High field and high frequency have been leading the development of electron cyclotron resonance ion sources (ECRISs) in the past decade as demonstrated by the achieved great performance. The present superconducting magnet structures built with NbTi wires have reached an axial field of 3.5-4.0 T and a radial field of 2.0 T for operating frequency up to 28 GHz. Further increase of the magnetic field strength will require higher current superconductor, i.e., Nb(3)Sn wires. This paper will present the features of a new superconducting magnet structure and review of the existing structures. Using NbTi wires, the new magnet structure could be able to produce maximum fields of 7.0 T on axis and radial field of 3.7 T at a hexagonal plasma chamber wall for ECRIS operations up to 50 GHz. If this new magnet can be built with Nb(3)Sn wires, much higher fields can be expected.     

基于GB150—2011设计的冷却器疲劳分析

基于GB 150—2011设计的核电厂CRDM试验台架用冷却器在设计寿命期间将承受压力和温度的循环载荷,需考虑其发生疲劳失效的可能性。应用ANSYS有限元软件建立冷却器的局部三维有限元模型,根据设计瞬态的特点对其进行合并与分组,在最大峰值应力强度所在区域设置评定截面,并根据JB/T 4732—1995附录C的相关规定进行疲劳分析和评定,为保证冷却器在设计寿命内的结构完整性提供依据,也为其他设备在类似瞬态工况下的疲劳分析提供借鉴。     

A superconducting magnetic-energy storage system as a source of high-power current pulses with constant amplitude

A facility is described that allows generation of long current pulses with a virtually constant amplitude by a superconducting inductive (magnetic) energy storage with a 5-MJ energy content. The design of this facility ensures the possibility of changing the parameters of an output current pulse by varying the inductances of the magnetic-system’s sections and their electromagnet coupling. This approach allows not only the stabilization of the current pulse but also a severalfold increase in the initial current value. The electric insulation of the storage’s coil can withstand a voltage higher than 200 kV, and a special system of multielectrode current leads can transfer a power of up to 250 MW at a 1.3-kA current from the cold zone (4.2 K) into the warm (300 K) zone almost without energy losses. The current can be increased to 10 kA by changing the connection of the facility’s sections. The facility has been tested in six full-scale experiments and is ready for further tests as a component of electrophysical facilities of various purposes.     

Precooling of a superconducting magnet using a cryocooler and thermal switches

A simple precooling system for a superconducting magnet is developed using a Cryomech GB02 cryocooler and gas filled thermal switches. A superconducting magnet (NbTi wire, 7 T of maximum field, 5.6 kg of weight) is precooled to 16 K in about 70 h without any manual control. Heat transfer rate of each thermal switch (H2 or N2 gas filled at 1.3 MPa at room temperature) is about 3x10(-1) W/K during the ON state, and 5x10(-3) W/K during the OFF state.     

一种基于复杂永磁体阵列的悬浮式振动能量采集器的精确模型及验证

为提高振动能量采集器的输出性能和工作频带，基于永磁体阵列和多自由度器件受到广泛关注。然而这类器件存在磁场分布复杂，动态特性难以模拟等问题。以一种基于复杂永磁体阵列的可调频磁悬浮振动能量采集器为研究对象，建立器件解析模型和有限元模型的联合分析模型，理论模型显示系统具有非线性振动特性，其动力学模型可简化为Duffing方程形式，并通过有限元模型简化了对非线性系统的分析。利用COMSOL有限元仿真研究器件磁场分布、非线性磁力特性，分析磁力和线圈位置对器件输出特性的影响。搭建测试平台对研制的可调频磁悬浮振动能量采集器进行试验表征，以验证联合分析模型。试验结果表明，在20～35 mm的固定磁铁间距离变化范围内，器件谐振频率变化范围为8.6～13.1 Hz，0.35g加速度下输出电压峰峰值为352.9～658.2 mV，联合分析模型与试验之间具有一致性。     

Construction and calibration of a 12 T pulsed magnet integrated with a 4 K closed-cycle refrigerator

A low cost 12 T pulsed magnet system has been integrated with a closed-cycle helium refrigerator for performing magnetotransport measurements. Minimal delay between pulses and ac current excitation with software lock-in to reduce noise enables quick but accurate measurements to be performed at temperatures of 4-300 K up to 12 T. An additional pulsed magnet operating with a liquid nitrogen cryostat extends the range up to 19 T. The instrument has been calibrated against a commercial superconducting magnet by comparing quantum Hall effect data in a p-channel SiGe/Si heterostructure, and common issues arising out of pulsed magnet usage have been addressed. The versatility of the system is demonstrated through magnetotransport measurements in a variety of samples such as heterostructures, narrow gap semiconductors, and those exhibiting giant magnetoresistance.     

Experimental investigation of gas-liquid flow in a vertical venturi installed downstream of a horizontal blind tee flow conditioner and the flow regime transition

A venturi device is commonly used as an integral part of a multiphase flowmeter (MPFM) in real-time oil-gas production monitoring. Partial flow mixing is required by installing the venturi device vertically downstream of a blind tee pipework that conditions the incoming horizontal gas-liquid flow (for an accurate determination of individual phase fraction and flow rate). To study the flow-mixing effect of the blind tee, high-speed video flow visualization of gas-liquid flows has been performed at blind tee and venturi sections by using a purpose-built transparent test rig over a wide range of superficial liquid velocities (0.3–2.4 m/s) and gas volume fractions (10–95%). There is little ‘homogenization’ effect of the blind tee on the incoming intermittent horizontal flow regimes across the tested flow conditions, with the flow remaining intermittent but becoming more axis-symmetric and predictable in the venturi measurement section. A horizontal (blind tee) to vertical (venturi) flow-pattern transition map is proposed based on gas and liquid mass fluxes (weighted by the Baker parameters). Flow patterns can be identified from the mean and variance of a fast electrical capacitance holdup measured at the venturi throat.     

Wearable handwriting input device using magnetic field: Geomagnetism cancellation in position calculation

In this paper an efficient technique using magnetic field is proposed for wearable handwriting input. This device requires mounting a permanent magnet onto fingertip and detecting the magnetic field generated by the magnet through magnetic sensors at the wrist of the other hand. The position of magnet is calculated by the vector of the magnetic field. And a method is proposed to avoid geomagnetic influence, using two magnetic sensors. Numerical methods are used to calculate the position of magnet with geomagnetism cancellation. Two numerical methods have been adopted and compared. A prototype device is made and we succeeded to get the trajectory of handwriting input character.     

Design and characterization of a novel permanent magnet synchronous motor used in a growing prosthesis for young patients with bone cancer

Approximately 50 child sarcomas are treated with limb salvage surgery each year in the United Kingdom. These children need an extendable implant that can be lengthened periodically to keep pace with the growth in the opposite limb. Surgically, invasive devices have been used for the past 30 years with intrinsic problems of infection and long-term recurrent trauma to the patient. To eliminate problems associated with the invasive device, a noninvasive extendable prosthesis was developed. The magnetically coupled drive technology used for this prosthesis was a synchronous motor with a gear-driven telescoping shaft. In this design the motor configuration was in two parts: a rotating magnet (rotor) that fitted inside the prosthesis where space was limited and the stator, which was an external device used to extend the prosthesis remotely as the patient grew. This compact external drive produced a focused magnetic flux that required no cooling and operated on a single-phase power supply. The extending mechanism in the implant was able to overcome up to 1300 N force, which is the tension force exerted by the soft tissues during the lengthening procedure. The device has been successfully implanted in 50 patients.     

A novel design of permanent magnet wheel with induction pin for mobile robot

Robots are utilized to automate works on a vertical plane of a large structure such as a ship and permanent magnet wheels have been utilized to make possible the robots to be attached to vertical plane and be in motion. In this paper, we propose a new design of the permanent magnet wheel for mobile robots to improve the adhesive force and facilitate the detachment of the wheel. In newly suggested design, the magnetic flux enhances the adhesive force during the attachment while induction pins redirect magnetic flux in order to achieve an easier detachment. To characterize the performance, finite element analysis is executed and experiment apparatus is constructed. The results show that the adhesive force is reduced effectively by using induction pins.     

A Method and a Device Prototype for Noninvasive Measurements of Blood Perfusion in a Tissue

Noncoherent fluctuation spectroscopy (NFS) is described as an optical method for measuring the tissue blood perfusion. This method is based on the registration of low-frequency fluctuations of a backscattered signal from a tissue in the frequency range of 0–20 Hz. It allows the assessment of the blood-flow intensity in small blood vessels of the skin by calculating an integral parameter, the perfusion index, which is similar to that in the laser Doppler flowmetry (LDF) method. A device prototype in which LEDs at wavelengths of 568 and 808 nm are used in a miniature optical head was developed. The device makes it possible to perform diagnostics during the subject’s motion via the use of LED light sources. It is shown that the NFS signal is comparable with the LDF signal. Thus, the NFS method can serve as an inexpensive alternative to the LDF method.     

Penetration of the magnetic field of a marker placed inside a gas pipeline through a steel tube wall

The ELCUT program was used to model the penetration of the magnetic field of a dipole magnetized along a ferromagnetic tube’s axis through the tube wall. It was found for the first time that the induction of the dipole’s magnetic field increases after penetration though the ferromagnetic tube as compared to the field without this tube. It has been found that, near the dipole central cross section normal to the tube’s axis, the field is weakened (screened) by the tube, whereas, far from the dipole center, the field along the tube’s axis increases several times. It has been shown that the tube-induced field-screening and field-amplification coefficients are functions of the distance between the observation point and the dipole center, which is a field source.     

一种R-test球头球心检测装置结构优化设计方法

基于数控系统绕刀具中心旋转(Rotation tool center point,RTCP)功能,R-test装置被用于多轴联动数控机床的联动精度检测与标定。该仪器通过三个直线位移传感器测量安装于主轴的球头球心空间位置,从而可测量机床多轴联动时的刀具中心点位置误差。在分析测量原理的基础上,提出最大测量空间和测量敏感度的两个用于评价测量性能的指标及相应的数值算法,得到一种R-test装置结构优化设计方法。在选择通用球头芯棒与长度计的情况下,通过约束分析得到测量杆安装圆直径、测量杆与基准面夹角两个关键尺寸的设计区间,利用蒙特卡罗法搜索得到这两个关键尺寸的最优解,完成结构优化设计。仿真表明,优化设计得到的R-test测量装置具有最佳的测量敏感度,可测区域大于半径为4 mm的球体,能满足实际测量精度和测量空间需要。     

Magnetic microrheometer for in situ characterization of coating viscosity

A magnetic microrheometer has been designed to characterize the local viscosity of liquid-applied coatings in situ during solidification. The apparatus includes NdFeB magnets mounted on computer-controlled micropositioners for the manipulation of ～1?μm diameter superparamagnetic particles in the coating. Magnetic field gradients at 20-70 T/m are generated by changing magnet size and the gap distance between the magnets. A specimen stage located between two magnets is outfitted with a heater and channels to control process conditions (temperature and air flow), and a digital optical microscope lens above the stage is used to monitor the probe particle position. Validation studies with glycerol and polyimide precursor solution showed that microrheometry results match traditional bulk rheometry within an error of 5%. The viscosities of polyvinyl alcohol (PVA) solution and polyimide precursor solution coatings were measured at different shear rates (0.01-5?s(-1)) by adjusting the magnetic field gradient. The effect of proximity to the substrate on the particle motion was characterized and compared with theoretical predictions. The magnetic microrheometer was used to characterize the time-viscosity profile of PVA coatings during drying at several temperatures. The viscosity range measured by the apparatus was 0.1-20?Pa?s during drying of coatings at temperatures between room temperature and 80?°C.     

Performance measurement of a smoke extraction system for buildings in full-scale hot smoke test

The current inspection method for a smoke extraction system in Taiwan measures whether the air flow of the smoke vent conforms to the design value. However, this method is inapplicable to natural smoke extraction systems. As the plugholing effect is disregarded, adequate air flow cannot ensure that the system will exhaust smoke effectively during a fire. Hence, a full-scale hot smoke test for smoke extraction systems is necessary. Some international test criteria are formulated using visible smoke and alcoholic fuel which is pollution-free after combustion. The effectiveness is judged only by visually observing the smoke’s flow direction, which is indeed unscientific. This study used a string of vertical smoke layer measuring instruments composed of several approved photoelectric smoke detectors, as well as a light attenuation measuring device composed of illuminance meters to conduct tests on the effect of makeup air. The results proved that the former one uses different height induction times to judge the position of the smoke layer effectively, while the latter one uses the light attenuation rate to distinguish the smoke density instantly and accurately. The obtained experimental data were consistent with the onsite smoke distribution. The two sets of equipment designed in this study can be used for full-scale hot smoke tests to obtain performance data for a smoke extraction system.     

大间隙磁力传动系统驱动规律的仿真研究

针对已提出的大间隙行波磁场驱动的磁力传动系统,采用现代计算技术和数值计算中的有限元理论,运用ANSYS软件的磁场分析功能,建立了磁力传动系统的实体模型和有限元模型,通过模拟永磁体的角位移和电磁体线圈的通电状态,对系统工作过程进行了仿真;研究了系统永磁体在转动过程中的受力情况和各参数对系统驱动能力的影响规律,并进行了实验验证。研究结果表明:通过增加线圈匝数、线圈通电电流、永磁体外径和永磁体磁化强度,减小电磁体和永磁体间耦合距离,将电磁体和永磁体的相对位置沿x方向两侧(左侧或右侧)置于5 mm～10 mm范围内等方法,可提高系统的驱动力矩。     

Recuperative shock absorber

In the proposed device, some of the energy from the shock absorber is used to charge the vehicle’s battery. This device is based on the creation of emf in an induction coil wound on a frame whose axis is aligned with the shock-absorber piston.     

Design and commissioning of a high magnetic field muon spin relaxation spectrometer at the ISIS pulsed neutron and muon source

The high magnetic field (HiFi) muon instrument at the ISIS pulsed neutron and muon source is a state-of-the-art spectrometer designed to provide applied magnetic fields up to 5 T for muon studies of condensed matter and molecular systems. The spectrometer is optimised for time-differential muon spin relaxation studies at a pulsed muon source. We describe the challenges involved in its design and construction, detailing, in particular, the magnet and detector performance. Commissioning experiments have been conducted and the results are presented to demonstrate the scientific capabilities of the new instrument.     

络筒机卷绕部分设计分析

针对络筒机的卷绕部分做进一步的设计分析,主要是研究筒管的传动方式、卷取机构的相对位置、接触压力的调节等方面的问题。     

Commissioning and performance of the variable line spacing plane grating monochromator beamline at the Canadian Light Source

The variable line spacing plane grating monochromator beamline at the Canadian Light Source (CLS) employs three grazing incidence variable line spacing gratings to cover a photon energy range of 5-250 eV. It uses a 185 mm period length planar permanent magnet insertion device as the photon source, sharing a straight section with another soft x-ray beamline at the CLS. The commissioning and performance of the beamline is reported. The high resolution photoabsorption spectra of Ar and PF(5) gases are reported. A resolving power of over 40,000 for photons in the low energy region and >10,000 for a wider energy range (8-200 eV) can be achieved. A photon flux of up to 2 x 10(12) photons/s per 100 mA with slit settings of 50 microm has been measured.