Characterizing a proton beam with two different methods in beam halo experiments

In beam halo experiments, it is very important to correctly characterize the RFQ output proton beam. In order to simulate the beam dynamics properly, we must first know the correct initial beam parameters. We have used two different methods, quadrupole scans and multi-wire scanners to determine the transverse phase-space properties of the proton beam. The experimental data were analyzed by fitting to the 3-D nonlinear simulation code IMPACT. For the quadrupole scan method, we found that the RMS beam radius and the measured beam-core profiles agreed very well with the simulations. For the multi-wire scanner method, we choose the case of a matched beam. By fitting the IMPACT simulation results to the measured data, we obtained the Courant-Snyder parameters and the emittance of the beam. The difference between the two methods is about eight percent, which is acceptable in our experiments.     

Z箍缩等离子体电流分布实验研究

在"强光一号"装置上, 利用微型磁探针系统测量了钨丝阵负载内部的消融等离子体携带的电流, 对比了有无泡沫柱两种负载条件下内部电流分布的差异, 获得了稳定可靠的实验数据. 实验中使用了由42 根4.2 μm 钨丝组成的直径12 mm 的丝阵负载, 脉冲电流峰值为1.34 MA, 上升时间约70 ns. 结果表明: 在电流放电开始约20 ns 后, 半径3.2 mm 处的磁探针有明显的信号输出, 随后的20 ns 内, 内部等离子体分流比迅速上升至约20%, 并在30—40 ns 内基本保持稳定. 丝阵加载泡沫柱后, 内部电流值在Z 箍缩前期没有明显变化.     

中学物理教学中多媒体的应用探究

随着科学技术的不断进步,在我们的教学过程中也出现了许多新的教学工具,这些新的教学工具的使用能让教师更好的完成教学任务.其中,多媒体的应用就是其中之一.本文主要针对中学物理教学中多媒体的应用做出一定的探究,并且希望能对今后的物理教学做出一定的贡献.     

真空紫外-紫外光激发下的Na_2SO_4:TbF_3的发光性质

在空气中900℃温度下,对纯天然无水芒硝(Na2SO4)和TbF3的混合粉末加热20min,制备了Na2SO4:TbF3发光材料。并测量了在室温中真空紫外-紫外光下的发射和激发光谱。发射光谱有一系列由于Tb3+离子的5D4→7FJ(J=6,5,4,3,2)和5D3→7FJ(J=6,5,4,3,2)跃迁发射峰。通过监测542nm处发光得到的激发光谱,分别由Tb3+离子4fn→4fn-15d跃迁(187,193,218nm),基质吸收(165,200,240nm)引起的强激发谱和禁戒的f-f跃迁产生的弱激发谱组成。在TbF3的掺杂量在0.3%～2%范围内,随着Tb3+离子掺杂量的增加,真空紫外区的激发谱相应地逐渐增强。     

溅射法制作的Fe-Al-O颗粒薄膜的磁化曲线及巨磁阻曲线的测定

用溅射法制作了不同的Fe-Al2O3颗粒薄膜，用样品振动型磁力计测定了磁化曲线和巨磁阻曲线，并对其进行了分析和讨论．     

Standing Shocks in Viscous Accretion Flows around Black Holes

We study the problem of standing shocks in viscous accretion flows around black holes. We parameterize such a flow with two physical constants, namely the specific angular momentum accreted by the black hole j and the energy quantity K. By providing the global dependence of shock formation in the j - K parameter space, we show that a significant parameter region can ensure solutions with shocks of different types, namely Rankine-Hugoniot shocks, isothermal shocks, and more realistically, mixed shocks.     

V型腔腔内和频产生3 W连续波589 nm黄光激光器

报道了双Nd：YAG棒串接V型折叠腔腔内KTP和频全固态黄光激光器，得到了3 W连续波589 nm黄光输出.为了提高黄光输出功率，采用了两种手段：一是通过优化腔型设计使得两束基频在腔内达到了最佳的空间重合，二是通过选择合适大小的二极管激光器的抽运功率使得两束基频在腔内达到了最佳的功率配比. 关键词： 全固态激光器 Nd：YAG激光器 黄光 腔内和频     

分段共振耦合RFQ的调谐与测量

对一长度为3m的分段共振耦合RFQ冷模进行了多次调谐和测量,得到了RF电场平整度好于4%的场分布;解决了分段共振耦合RFQ调谐时耦合单元处RF电场分布出现的台阶问题;确定了分段共振耦合RFQ的调谐步骤.     

对制流特性曲线的一点看法

对制流特性曲线的一点看法孙新义，杨德甫（延安大学物理系，７１６０００）《普通物理实验》（二、电磁学部分）”’４６页的制流特性曲线（图１）与制流电路（图２）的理论分析结果不一致．现提出我们的看法以供讨论．图１制流特性曲线图图２制电流路图［１］中对制流电...     

RF power coupling for the CSNS DTL

The China Spallation Neutron Source (CSNS) drift tube linac (DTL) consists of four tanks and each tank is fed by a 2.5 MW klystron. Accurate predication of RF coupling between the RF cavity and ports is very important for DTL RF coupler design. An iris-type coupler is chosen to couple the RF power to the DTL accelerating cavity. The physical design of the DTL coupler and the calculations of RF coupling between the cavity and coupler are carried out. The results from the numerical simulations are in excellent agreement with the analytical results.