磁重联的研究

磁重联是等离子体物理的一个主要课题.从有限阻抗引起重联的动力学过程出发,分析了磁重联的各种模型,介绍了磁场线重联规律中的几个重要概念.     

静磁场屏蔽实验的探讨

本对静磁场屏蔽作出理论分析外，同时设计了一个实验来验证这个理论。     

Calculating magnetic shielding effectiveness for high-power dc comparator by magnetic circuit method

Magnetic shielding is very important in the design of a high-power dc comparator. This paper addressed the application of magnetic circuit method to calculate the magnetic shielding effectiveness of high-power dc comparators when an external radial magnetic field is added. The mathematical relationship between the magnetic shielding effectiveness and the parameters of the magnetic shielding body were obtained. To verify the validity of the calculation method, we developped a procedure to measure the magnetic shielding effectiveness of the magnetic body by measuring the induction voltage of the detection winding instead of the magnetic intensity at a point in the magnetic shielding body, making the manipulation much easier. The result calculated with the magnetic circuit method turns out to be closer to the measured one compared with that calculated with a conventional algorithm proposed by Ren, suggesting that the magnetic circuit method is an applicable tool for estimating the toroidal cavity magnetic shielding effectiveness of a heavy current comparator when a radial magnetic field is added.     

汲取一泓清泉

当一张张图片、一段段视频被浪花夹带着,迸溅进我们的眼瞳时,我们惊喜。当一位位草根,在人生的大海上勇敢地扬帆起航时,我们羡慕。当一次次的灌水让我们喘不过气来时,我们慨叹。     

溶液凝胶自然燃烧制备的铝掺杂对钡铁氧体晶相和磁性能的影响

Al-substituted barium ferrite powders were synthesized using the sol-gel auto-combustion method according to the molecular formula BaAlxFe12-xO19 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0). Compared with non-substituted barium ferrite annealing at 1000℃, the vibrating sample magnetometer (VSM) measurement manifested that the optimum magnetic properties formation temperature of Al-substituted barium ferrite was 1100℃. The data from X-ray diffractometer (XRD) showed that with increasing x, the lattice constants (a and c) decreased as well as the unit-cell volume Vcell. Magnetic measurement of non-substituted and Al-substituted powders annealed from 900℃ to 1200℃ exhibited that the maximum magnetization M (10 kOe), the remanent magnetization Mr and the coercivity Hc depended strongly on the chemical composition of powder as well as the annealing temperature. When annealing at 1100℃, BaAl0.5Fe11.5019 of high coercivity Hc (6584 Oe) was produced. Meanwhile, M (10 kOe) and Mr were 42.83emu/g and 25.65emu/g, respectively.     

电磁学中的两个问题

文章给出了平面载流线圈在均匀磁场中所受的磁力矩公式的一种简化证明方法,并对同轴电缆自感的计算中把一段同轴电缆的电感看成一个线圈的电感的观点进行了论证.     

Sm部分取代Tb对TbCo／Cr薄膜磁光性能的影响

利用磁控溅射法制备了SmTbCo/Cr薄膜,分析了Sm含量对SmTbCo/Cr薄膜磁光性能的影响.结果表明:随着Sm含量的增加,(SmxTb1-x)31Co69薄膜的Ms、θk和R增加,而Hc随之减少;Sm含量在0.286～0.343范围内的(Sm0.286Tb0.714)31Co69(120nm)/Cr(240nm)和(Sm0.343Tb0.657)31Co69(120nm)/Cr(180nm)薄膜的磁光性能均满足光磁混合记录对介质的要求.     

复合磁垒纳米结构中的量子输运

提出了复合磁垒的概念并研究了复合磁垒纳米结构中电子的隧穿输运性质.对照相应的非复合磁垒结构, 这种磁纳米结构大大增强了电子的波矢滤波特性.当考虑电子的自旋与非均匀磁场的相互作用,这种磁垒纳米结构具有很强的电子自旋极化效应.     

中考直通车：第二十讲 电和磁

本讲知识点比较多且琐碎，主要的考点有：电流的磁场；电磁铁的性质；磁极间的相互作用；磁场的性质；安培定则及应用；电磁感应现象及产生感应电流的条件；感应电流方向的判断；磁场对电流的作用；发电机、电动机的工作原理及能量转化、换向器的作用；电能的输送等内容．其中，安培定则、通电螺线管的磁场、影响电磁铁磁性强弱的因素、     

磁量子结构中电子自旋极化输运性质的研究

研究了双磁垒量子结构中,磁场强度和偏压大小对电子自旋极化输运的影响。结果表明:零偏压下,电子在反平行等强磁垒结构中输运不会产生自旋极化;电子传输的阈值能量随磁场强度或偏置电压的增大而增大;在一定的磁场强度和偏压大小下,比较由半导体InAs和GaAs两类材料构成的量子结构中电子输运自旋极化度,发现它们的电子输运自旋极化度都随入射能量的增大而呈振荡衰减趋势,朗德有效因子高的InAs材料比GaAs的自旋极化度高出一个数量级。