脉冲强磁体的概念性设计和行为仿真

本文对一个内径为10 mm、能产生60T场强、持续脉冲时间为10 ms的强磁体的相关参数进行了设计计算,并对该强磁体在不同脉冲电源条件下的电特性行为进行了仿真.     

脉冲磁体中不锈钢筒对磁场的影响研究

建立脉冲磁体线圈与不锈钢筒之间电磁耦合分析模型,利用数值分析法,对不锈钢套筒对磁场波形的影响进行理论分析与计算.结果表明,不锈钢套筒增加了放电回路中的等效电阻,降低了等效电感,导致磁场到达峰值时刻的时间缩短,磁场峰值降低.壁厚20 mm的不锈钢筒,磁场峰值降低4.9%,磁场达到峰值时间缩短6.7%.实验结果与理论分析吻...     

紧凑型脉冲磁场发生装置研制

研制并测试一套紧凑型脉冲强磁场发生系统,包括一套1mF/8kV高储能密度电容器电源、两台脉冲磁体和一套监控系统。系统分别在27mm和45mm的大孔径内产生最高为20T和10T的脉冲磁场。     

41T脉冲强磁■

引言目前,稳态磁场被限制在20T上下的水平,主要是线圈耗散大约为10MW量级的功率所引起的冷却问题难于解决。当磁场在50T时,劳仑兹所引起的机械应力,可与磁体的结构强度相比拟,因而当磁场大于50T时,人们不得不使用非常坚固的单层比特线圈。但它却大大缩短了脉冲时间。研究长脉冲磁场,可获得既能节省功率,又有足够持续时间的强磁场线圈。     

12.5特斯拉NbTi-Nb_3Sn组合超导磁体系统的研制

本文介绍了一个NbTi-Nb_3Sn组合高场磁体系统。该磁体的内外磁体可拆卸,并可分别使用。该磁体有效内径为30mm,中心场可达12.58T,可用于超导材料、结构材料性能测试,并可为其它一些物理实验提供高磁场条件。该磁体系统采用内外磁体分别供电,供电电源为两台300A稳流电源。磁体系统实验杜瓦采用内径为400mm的多屏绝热低温恒温器,在实验的过程中,正常液氦的消耗量约为1L/h。     

脉冲强磁体专用设计软件开发

在设计脉冲强磁体时,需综合考虑材料的电性能、热性能和机械性能,优化磁体结构,使其达到最佳。本工作开发的脉冲强磁体专用设计软件,不仅能准确计算放电过程、温度和应力分布,还能使用优化技术,寻找最佳磁体结构,提高磁体设计水平和效率。实验结果表明,软件分析结果与实验结果吻合。     

用于4mm回旋管的超导磁体

描述了一个4mm回旋管用的超导磁体,它可在谐振腔区提供3T的均匀磁场,均匀区长6cm,均匀度优于±0.16%,均匀磁场又可调节成梯度场,梯度△B/B_o≥8.5%。阴极区磁场均匀区长4cm,均匀度±(1.0～1.8)%,压缩比B_k/B_o可在1/6～1/15范围内调节。采用四台电源串联供电。磁场位形调节好后,磁体可实现闭环运行。磁体将与回旋管配合在HL-1装置上进行ECRH物理实验。     

脉冲强磁体中应力的有限元分析

提高脉冲磁场强度的主要障碍是磁体中巨大的应力,而脉冲磁体中应力的产生和作用过程比较复杂,要准确地计算出来很困难。采用有限元法对脉冲磁体中的应力进行分析,计算中全面考虑了预应力、电磁力、热应力等情况。通过计算,得出了,一些设计脉冲磁体的基本原则。     

用于钠泵的螺管型超导磁体设计与实验

本文对钠金属电磁泵的螺管型超导磁体部分进行了详细设计和实验研究.磁体设计指标为水平室温孔长度600mm,直径160mm,中心场磁感应强度5T.对超导磁体所用的超导线进行了短样测试,当温度为4.2K、磁感应强度为5T时,临界电流为464A,大于工作电流.磁体经过绕制、真空压力浸渍工艺后进行10次失超锻炼,在失超电流97 A的电流下测试,磁体中心磁感应强度达到4.66T.若进一步降低励磁速率,磁体中心磁感应强度预计可以达到5T左右,可以满足钠金属电磁泵的要求.     

脉冲强磁场高功率脉冲电源系统研制

本文介绍了用于脉冲强磁场大功率电源系统工作原理及研制工作。该系统由58台55心电容器提供1．0MJ储能，采用真空合闸开关作为主放电开关，由大功率二极管和电阻串联构成续流回路。整个脉冲电源系统可以输出最大脉冲宽度30ms，峰值30kA可调脉冲电流，以适应不同参数脉冲磁体实验需要。初步实验已达到30ms脉宽、35T脉冲磁场，该脉冲电源系统工作稳定可靠，具有抗干扰能力，达到设计参数要求，为今后更高参数脉冲强磁场科学实验装置研制提供了重要参考。     

Measurement system for SSRF pulsed magnets

This paper describes the magnetic field measurement system for pulsed magnets in SSRF.The system consists of magnetic probes,analog active integrator,oscilloscope,stepper motor and a controller.An application pro- gram based on LabVIEW has been developed as main control unit.After the magnetic field mapping of a septum magnet prototype,it is verified that the test results accord with the results of theoretical calculation and computer simulation.     

Hydrogen-Oxygen MHD Generator Applied to Pulsed Power Required in Nuclear Fusion Research

Designs of large test facilities of nuclear fusion research succeeding the current large Tokamaks such as TFTR, JET and JT-60 show that huge pulsed power is required to operate the new test facilities; 700 MW for 10 s to excite poloidal coils. The present paper proposes three steps of application of MHD power generation to fusion to provide such large pulsed power. The first step is to design and construct a small scale MHD generator which excites the Demo poloidal superconducting magnet (SCM) coil being under construction in JAERI. The operating current is 30 kA with the stored energy of 40 MJ. As the working gas of MHD generator, H2-02 combustion product is selected, seeded with 5%K. The second and third steps are to construct an intermediate MHD channel of 100 MWe and a large channel of 800 MWe. Much improved designs are obtained in the present study, compared with the previous designs. For the large 800 MW generator, the maximum magnetic field becomes 3.5 T with the load current of about 100 kA, while the stored energy in the MHD magnet is estimated to be less than 0.5 GJ which is much smaller than 5~8 GJ of planned poloidal coils. The small MHD channel designed for the Demo poloidal coil is 4 m long with the peak field of 1.8 T. The cryogenic magnet can be self-excited within 20 s. The Demo poloidal coil is charged in about 4 s.     

A 7 T Pulsed Magnetic Field Generator for Magnetized Laser Plasma Experiments

A pulsed magnetic field generator was developed to study the effect of a magnetic field on the evolution of a laser-generated plasma.A 40 kV pulsed power system delivered a fast(~230 ns),55 kA current pulse into a single-turn coil surrounding the laser target,using a capacitor bank of 200 nF,a laser-triggered switch and a low-impedance strip transmission line.A one-dimensional uniform 7 T pulsed magnetic field was created using a Helmholtz coil pair with a 6 mm diameter.The pulsed magnetic field was controlled to take effect synchronously with a nanosecond heating laser beam,a femtosecond probing laser beam and an optical Intensified Charge Coupled Device(ICCD) detector.The preliminary experiments demonstrate bifurcation and focusing of plasma expansion in a transverse magnetic field.     

Preliminary design of KTX magnet system

KTX is a reversed field pinch magnetic confinement device of which the magnet system is designed in ASIPP and USTC. The main parameter of KTX is between RFX and MST. Its magnet system includes the toroidal field (TF) winding and poloidal field (PF) winding (ohmic heating winding and equilibrium field winding), which are less complex than tokamak device due to the fact that a tokamak requires a superconducting system to perform quasi-steady state operation and achieve Q > 10. However, the most important part of the magnet system design lies in how to keep the TF magnetic field ripple, as well as any kinds of stray field, to a minimum value. The main design activities of the KTX magnet system are presented as detailed as possible in this paper, and the main activities which have already been completed include magnet coils position and winding, insulation design, plasma modeling prediction, thermal analysis, magnetic field calculations were analyzed and so on. The magnet system design is one of the major activities for KTX device design, which is effective guarantee for the future R&D and manufacture. Besides, the detailed design activities should be continuously optimized and changed based on the results from future R&D and relevant tests.     

Development and Investigation of a Dipole Magnet with a High-Temperature Superconductor Winding

The structure of a dipole magnet with an iron yoke, where the winding is made of a Bi-2223 high-temperature superconductor, has been developed and the magnet has been built at the Institute of High-Energy Physics. The magnet has also been tested. A magnetic field 0.9 T has been attained in the aperture at temperature 65 K and 1.9 T at 4.2 K. The special features of the magnet structure are described and the results of testing of the magnet in a submerged cryostat at different temperatures are presented.     

The reversed field pinch reactor

The physical properties and engineering concepts of reversed field pinch reactors are presented and illustrated by two recent designs developed at Culham Laboratory and Los Alamos Scientific Laboratory. Both designs employ ohmic heating to ignite the plasma, operate in the pulsed mode without refuelling during the burn, and utilize superconducting magnetic field coils. Similarities between the two designs include the choice of plasma minor radius of 1.5 m, the use of low wall loading and electrical power output under 1 GW, and reasonable agreement on plasma behaviour. Major differences occur in the engineering design. The Culham design includes a separate radiation shield first wall behind which lies a passive stabilising shell. Large segments are required, implying the movement of toroidal field coils for maintenance of the helium cooled blanket. In the LASL design more conventional pressurized water cooling technology is used and the radiation shield and passive shell are combined, sacrificing thermal efficiency for an improvement in maintainability. The advantages of the reversed field pinch in higher beta, lower toroidal field, lower magnet costs and lack of auxiliary heating requirements appear at this stage to be significant when comparison is made with a pulsed tokamak reactor designed under the same ground rules.     

Development of Thin-wall Vacuum Chamber for Heavy Ion Medical Accelerator

Heavy Ion Medical Machine (HIMM), developed by the Institute of Modern Physics, Chinese Academy of Sciences, is the first medical heavy ion accelerator with independent intellectual property rights in China. Because the RAMPING mode was used for high frequency pulse dipole magnets of HIMM and the rising rate of magnetic field is 1.6 T/s, the vacuum chamber installed in the high frequency pulsed magnet is a thin-wall stainless vacuum chamber with reinforcing ribs to reduce the influence of eddy current on the ion beam stability. However, the gap size of magnet occupied by thin-wall stainless vacuum chamber with reinforcing ribs is too large, and it not only causes the high cost of magnets, but also greatly improves the maintenance cost. Based on these reasons, a new thin-wall vacuum chamber (0.3 mm) with ceramic lining was put forward and the prototype was designed and manufactured. The test results show that the obtained pressure of the prototype is in the order magnitude of 10^-10 Pa, and the magnet gap can be effectively reduced. And it is the development direction of thin-wall vacuum chamber of accelerator in the future.     

医用重离子加速器薄壁真空室研制

中国科学院近代物理研究所研制的医用重离子加速器装置是我国第1台拥有自主知识产权的医用重离子加速器,其高频脉冲二极磁铁使用RAMPING工作模式且磁场上升速率为1.6 T/s,所以安装在高频脉冲磁铁内的真空室采用一种薄壁加筋结构不锈钢真空室以减少涡流对离子束稳定性的影响。然而由于薄壁加筋不锈钢真空室占用磁铁气隙尺寸偏大,不仅造成了磁铁造价成本偏高,更是提高了运维成本。基于以上原因,本文提出陶瓷内衬薄壁（0.3 mm）真空室,并研制了原理样机。测试结果表明：样机真空度进入了10^-10 Pa量级范围,并可有效减小磁铁气隙,是未来加速器薄壁真空室的发展方向。