25 resultados para magnets


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The FAIR China Group (FCG), consisting of the Institute of Modern Physics (IMP Lanzhou), the Institute of Plasma Physics (ASIPP, Hefei) and the Institute of Electric Engineering (IEE, Beijing) developed and manufactured in cooperation with GSI, Germany a prototype of a superferric dipole for the Super-Fragment-Separator of the FAIR-project [1]. The dipole magnets of the separator will have a deflection radius of 12.5 m, a field up to 1.6 T, a gap of at least 170 mm and an effective length of more than 2 meters to bend ion beams with a rigidity from 2 T . m up to 20 T . m. The magnets operate at DC mode. These requirements led to a superferric design with a yoke weight of more than 50 tons and a maximum stored energy of more than 400 kJ. The principles of yoke, coil and cryostat construction will be presented. We will also show first results of tests and measurements realized at ASIPP and at IMP.

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The Super-FRS (Super FRagment Separator) is a part of FAIR (Facility for Antiproton and Ion Research), which will be constructed at GSI, Germany by 17 countries. The Super-FRS comprises 24 superferric dipole magnets. The 2D and 3D magnetic field simulations of the prototype magnet are described in this paper. A passive trim slot and four chamfered removable poles are used to satisfy the required field homogeneity which is better than +/-3 x 10(-4) at 1.6 T, 0.8 T and 0.16 T in a wide elliptical useable aperture of 380 mm x 140 mm. Measurement results at various field levels are shown in this paper as well. It can be seen from the comparison of calculation and measurement results that the magnetic designs of the magnet fulfils the requirements.

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特殊磁铁主要指用于同步加速器束流的注入和引出系统中的各类磁铁,如切割磁铁、BUMP磁铁、KICKER磁铁等。从结构和用途上来看,特殊磁铁基本属于二极偏转磁铁范畴;与常规的二极磁铁相比,只是在运行模式、磁场分布和好场区位置、杂散场分布、磁铁功能以及磁铁结构和材料等方面具有突出的特殊性。如切割磁铁的好场区要紧贴切割边,而切割边外侧的杂散场要降到主场的千分之一以下;BUMP磁铁和KICKER磁铁的磁场值不高,但要以很快的脉冲方式工作,所以就具有大电流、线圈匝数少的特点。各种特殊的性能要求使得特殊磁铁的设计和制造相当复杂。 HIRFL-CSR工程共有四台切割磁铁、四套BUMP磁铁以及两套KICKER磁铁用于加速器束流的注入和引出系统中。论文介绍了特殊磁铁的选型、材料选取、电磁设计、二维及三维磁场计算、电磁参数计算、冷却计算、结构设计以及工艺设计等磁铁设计的全部过程;另外,对磁铁研制的具体细节以及技术要求、加工制造以及测试结果也作了比较全面的介绍。论文将磁铁的二维及三维磁场计算作为设计和论述的重点;因为就目前的技术水平来说,二维及三维磁场的计算是磁铁设计的主要环节,是磁场优化的主要手段,也是其他主要电磁参数计算的基础。特别是三维磁场的计算结果,是磁铁设计的主要技术依据,是一种仿真度极高且经济实用的模拟过程。一些比较成熟的磁场计算软件,如TOSCA、ANSYS、MAFIA等更是具有人机界面简单、建模方便、计算结果直观可靠等优点。特殊磁铁的磁场计算所用的程序是TOSCA;从文中提供的测试结果看,计算结果与实测值的误差只有 1 %,可见其结果是极其可信的。从测试和运行结果来看,各种特殊磁铁的研制是成功的。特殊磁铁的成功研制为HIRFL-CSR的束流注入和引出提供了硬件基础

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本文从磁场测量的一般方法出发,简要介绍了磁场测量的基本理论和HIRFL-CSR(兰州重离子加速器冷却储存环)的二极铁积分测磁装置。测量装置主要包括探测线圈、积分器、步进电机驱动卡、步进电机、移动小车等。从HIRFL-CSR主环H型二极磁铁的设计要求出发, 根据积分测量的基本原理,着重介绍了CSR主环二极磁铁磁场分布测量、分散性测量、传递函数测量的方法、数据处理的方法和过程、及最后的测磁结果。为了提高测量结果的精度,使用了相对测量的方法,另外在分散性测量的论述中,用数学方法对相对测量进行了推导。在磁场分布性的测量中,根据测磁数据分析计算了磁场的高阶分量和二级铁的等效偏转角度随电流变化的结果。在测量分散性的过程中,对磁场垫补以达到CSR工程要求的方法和磁场特性了研究。在特殊磁铁的测量中,对调整线圈的磁场垫补的作用进行了测量。在CSRm二极铁的测量中,测磁的误差被给出, 且符合工程要求。

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HIRFL is a tandem cyclotron complex for heavy ion. On the beam line between SFC and SSC, there is a stripper. Behind it, the distribution of charge states of beam is a Gauss distribution. The equilibrium charge state Q_0 is selected by 1BO2(a 50° dipole behind the stripper) and delivered to SSC. One of two new small beam line (named SLAS) after 1B02 will be builded in or der to split and deliver the unused ions of charge states (Q_0 ± n) to aspecific experimental area. Q_0 ± n ions are septumed and separated from initial(Q_0) ion beam by two septum magnets SM1, SM2. The charge state selected by SM1 will be Q_0 ± 1(6 ≤ Q_0 < 17), Q_0 ± 2(17 ≤ Q_0 < 33) and Q_0 ± 3 (Q_0 ≥ 33) forming a beam in one of the two possine new beam line with the stripping energy of (0.2 to 9.83 Mev/A), an emittance of 10π mm.mrad in the two transverse planes and an intensity ranging from 10~(11) pps for z ≤ 10 to some 10~5 pps for the heaviest element. Behind SM2, a few transport elements (three dipoles and seven qudrupoles) tra nsport Q_0 ± n beam to target positions T1, T2 (see fig. 1) and generate small beam spots (φ ≤ 4mm, φ ≤ 6mm). The optics design of the beam line has been done based on SLAC-75 (a first and second - order matrix theory). beam optics calculation has been worked out with the TRANSPORT program. The design is a very economical thinking, because without building a new accelerator we can obtain a lower energy heavy ion beam to provide for a lot of atomic and solid state physical experiments

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Calixarene-capped Co-32 clusters are constructed by a sodalite Co-24(II) cage and an encapsulated Co-8(III) cube. The spherical units are arranged into three isomeric structures, two of which are stacked by the bcc lattices and the third of which is assembled by the cubic closest packing of the spherical units.

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A mononuclear tri-spin single-molecule magnet based on the rare earth radical [Tb(hfac)(3)(NITPhOEt)(2)] (NITPhOEt = 4'-ethoxy-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) has been synthesized, structurally characterized and the alternating current signals show a slow relaxation of magnetization and frequency-dependent signals.

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Cobalt ferrite one-dimensional nanostructures (nanoribbons and nanofibers) were prepared by electrospinning combined with sol-gel technology. The nanoribbons and nanofibers were formed through assembling magnetic nanoparticles with poly(vinyl pyrrolidone) (PVP) as the structure-directing template. Nanoribbons and nanofibers were obtained after calcining the precursor nanoribbons at different temperatures. Successive Ostwald ripening processes occur during the formation of CoFe2O4 nanoribbons and nanofibers. The sizes of nanoparticles varied with calcination temperatures, which leads to different one-dimensional structures and variable magnetic properties. These novel magnetic one-dimensional structures can potentially be used in nanoelectronic devices, magnetic sensors, and flexible magnets.

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Two novel coordination polymers Ni-4(CH3O)(4)(CH3OH)(4)(dca)(4) (1) and Co-4(CH3O)(4)(CH3OH)(4)(dca)(4) (2) have been synthesized by solvethermal reaction. X-ray single-crystal analysis reveals that the two complexes are isostrutural and possess 3D frameworks that are built from the M4O4(M= Ni (1) and Co (2)) cubanelike building blocks linked by dicyanamide (dca) bridges. The temperature dependence of the magnetic susceptibility was measured and the DC experiment data were fitted using the Heisenberg spin Hamiltonian.

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A series of W-type ferrites with the composition of Ba1-xLaxCo2Fe16O27 (where, x = 0.0, 0.05, 0.10, 0.15, 020 and 0.25) were prepared by solid-state reaction method. The structure transformations of the ferrites were examined by XRD, DTA-TG and XPS, and the microwave-absorbing properties were investigated by evaluating the permeability and permittivity of materials (mu(r), epsilon(r)). The results showed that the phase-transition temperature increased with the addition of La2+ content, and a single-phase was formed at 1250 degrees C at last. Microwave properties were obviously improved as a result of the substitution of La3+ for Ba2+ at the frequency range of 0.5 similar to 18.0 GHz.