多级柱面炸药内爆磁通量压缩技术研究

柱面内爆磁通量压缩发生器是利用炸药内爆压缩其内部磁通量至轴线附近小体积内从而实现超高磁场,传统的单级装置因受到金属套筒内爆失稳等影响性能指标受限。开展了多级内爆磁压缩技术研究,突破多项关键技术,包括研制特殊结构的密绕螺线管、脉冲功率源及大电流放电开关等,具备在直径135 mm套筒空间内实现20 T以上初始磁场产生能力,并建立了动态磁光测量系统。利用磁流体力学编码SSS-MHD开展多级装置设计,计算显示,设计的多级装置能够将约42%的初始磁通量压缩至轴线附近直径7 mm的空间内。最终研制成功多级内爆磁压缩装置CJ-150,在亚立方厘米以上空间实现轴向峰值磁场强度906 T,数据不确定度5.35%。10余发动态考核实验显示,CJ-150装置工作稳定,能够满足物理实验需要。利用经实验验证的磁流体模型计算显示,CJ-150具备1 000 T以上超强磁场产生能力,能够对大尺寸样品实现500 GPa以上的准等熵加载。     

内爆磁压缩准等熵加载过程分析与实验验证

利用磁流体力学程序SSS-MHD模拟了炸药柱面内爆磁通量压缩发生器CJ-100装置的加载过程,讨论了各项装置参数的影响,结果表明装置可达到的峰值磁场值与初始磁场值成反比关系。设计了铁/铜夹层结构的样品靶,在该型装置上开展纯铁的准等熵加载实验。利用光子多普勒测速探头测量到6.43 km/s的样品靶自由面速度,在DT4铁中获得206 GPa的准等熵加载压力。铁材料的压力-比容曲线与理论等熵线基本重合,表明内爆磁压缩加载过程具有较高的等熵程度。     

X-pinch光源及其应用

介绍了X-pinch的基本原理、特点和在Z-pinch物理研究中的部分应用。X-pinch的负载及材料、驱动电流等可以根据需要进行调整，辐射点光源的时间分辨为0．7-2ns,空间分辨为1-5μm，X射线的能量范围从几百电子伏至几千电子伏。利用X-pinch作背光源对金属丝电爆炸进行诊断，可以得到等离子体柱横截面密度等。这些参数对正确理解金属丝阵内爆初级阶段的物理过程有重要意义。     

不同初始磁场对激波冲击R22重气柱过程影响的数值模拟

基于磁流体动力(magneto-hydrodynamic,MHD)方程,采用CTU+CT方法,对在不同初始磁场作用下的平面入射激波与磁化R22重质气柱作用过程进行了数值研究。数值结果清晰地描述了不同初始磁场条件时激波诱导R22气柱界面不稳定性的过程,揭示了磁场控制界面不稳定性的机理。另外,还分析了磁感应强度对界面不稳定性的影响,发现在磁场较小时,涡层附着于界面,但随着磁感应强度的增大,平均涡量随之增大,涡层与界面逐渐分离,最终更好地抑制了界面不稳定性。同时,还发现平均涡度拟能随着磁感应强度的增大而减小,而垂直磁场比平行磁场更能降低平均涡度拟能,因而平均涡度拟能可较好地反映磁场对不稳定性的影响效果。     

电磁法实验研究

概述了电磁法在爆炸力学中的应用及国外电磁法研究进展概况。介绍了电磁法测爆轰参数uc-1(pc-1),cc-1,a0（反应区宽度）和材料的动态参数u（质点速度）,σ（应力）等基本原理。设计并制作了一套磁头直径φ150毫米,磁隙宽120毫米,磁感应强度为2300高斯的磁场装置。用电磁法测定了注装TNT（密度1.60克/厘米3）炸药的uc-1为1.65±0.05毫米/微秒。初步测定了炸药加载时有机玻璃中质点速度和应力。新提出一种两台阶传感器串连方法联合测定质点速度和冲击波速度,从而可测定材料的状态方程。     

电磁加载下的高能量密度物理问题研究（续3）

4磁化靶聚变(MTF)研究4.1磁化靶聚变的基本概念为了满足Lawson判据,可以用磁场较长时间约束体积较大、温度与密度较低的氘氚等离子体(磁约束聚变,MCF),也可以用激光等高功率加载手段很快地在较小体积内造成温度与密度很高的等离子体(惯性约束聚变,ICF)。磁化靶聚变(magnetized target fusion,MTF)则是一种中间途径的概念,即把等离子体预先磁化(10T)并加热到适中温度(100~200eV)和密度(表3),再用电磁驱动的套筒内爆准等熵压缩到10keV温度,达到Lawson判据要求的状态(图41)。表3三种聚变技术途径参数的比较技术要求磁约束聚变磁化靶聚变…     

层状柱壳磁电复合材料的非线性磁电效应研究

本文基于超磁致伸缩材料非线性本构,从基本的控制方程出发,对层状柱壳磁电复合材料的非线性磁电响应进行理论研究,讨论了不同边界下磁场频率以及压电材料厚度比对磁电系数的影响,并得到了不同预压力下磁场大小对于磁电系数的影响。数值计算结果显示,对于Tefernol-D/PZT-5层状磁电复合材料,随着预压力值增大,磁电系数最大值减小,取得最大值时对应的磁场值逐渐增大;不同边界条件、磁场频率和磁场大小下,材料厚度比对磁电系数的也有着不同的影响。特别地当外加磁场频率较大时,相应于压电层厚度比,磁电系数呈现多极值现象。     

基于仿真与量纲分析的不同药量TNT内爆下多舱室结构毁伤规律研究

利用流固耦合算法,模拟了不同药量TNT内爆下大尺寸多舱室结构的毁伤效应。将各舱室划分为爆炸舱、共面邻舱、共边界邻舱和共点邻舱,再划分内爆下多舱室结构的毁伤等级。通过量纲分析,研究了内爆载荷下舱壁的变形失效规律,推导了内爆下多舱室结构的无量纲毁伤数,该毁伤数考虑了内爆载荷、材料性能和作用空间等因素,最后给出快速毁伤预测方法。研究结果表明:（1）内爆下多舱室结构的毁伤特点主要表现为舱壁挠曲变形、舱壁中心冲切失效、舱壁边界撕裂;（2）舱壁挠曲变形的挠厚比δ/H和固定边界撕裂的裂缝长厚比l/H均与药量-单舱室容积比m/V有明显线性关系;（3）提出的无量纲毁伤数和快速预测方法能够反映内爆下多舱室结构的毁伤情况,可为舰船毁伤研究提供参考。     

Z箍缩内爆过程磁场形式和能量转换

从理论上分析Z箍缩内爆过程磁场存在的形式和存在的条件、能量转换机制。介绍一种非经典的能量转换机制——"磁泡"效应,该机制表明即使在内爆的滞止阶段(等离子体宏观速度为零),仍然有磁能通过"磁泡"效应转换成等离子体热能。     

磁场对双液滴运动及加速聚结的影响分析

建立了油液中单个液滴在磁场作用下的力学模型,对双液滴在磁场作用下的移动聚结进行了理论分析;研究了油液中水平双液滴的间距随着磁感应强度和容器倾斜角度的变化规律。结果表明:随着磁感应强度的增大,双液滴的移动距离均增大并且双液滴中心间距为1cm,磁感应强度为400mT～500mT时,双液滴的移动距离最快;随着倾斜角度的增大,双液滴的移动距离呈现波浪变化趋势并有最佳的倾斜角度;容器倾斜一定角度时,液滴在重力分力作用下运动并切割磁感线产生洛伦兹力和电场力,加大了液滴的碰撞几率,从而促进了液滴的聚结。     

Thomson and rotation effects during photothermal excitation process in magnetic semiconductor medium using variable thermal conductivity

This study investigates a strong magnetic field acting over an elastic rotator semiconductor medium. The Thomson effect due to the magnetic field during the photothermal transport process is studied, and the thermoelectricity theory is used to explain the behavior of waves in the homogenous and isotropic medium under the effect of variable thermal conductivity. The variable thermal conductivity is considered as a linear function of the temperature. The two-dimensional deformation equations are used to describe the overlaps among plasma, electrical, thermal, and magneto-elastic waves.The charge density of inertia-particles is considered as a function of time for studying the induced electric current. The normal mode analysis is used to obtain the exact solutions of the physical field distributions as part of this phenomenon. To obtain the complete solutions of the physical field quantities, the certain mechanical loads, electromagnetic effects, thermal effects, and plasma recombination process are applied herein. The results of the physical distributions are graphically depicted and discussed in consideration of the internal heat source, rotation, and Peltier coefficient.     

Heating of a medium as a result of Joule energy dissipation

It is well known that when a magnetic field is present and electric currents flow through a gas, terms over and above those present in the case of ordinary thermal conductivity appear in the heat flux density vector. If the gas is dense enough and the magnetic field not over large, then the anisotropy caused by the magnetic field may be neglected. However, for a sufficiently large electric current a term proportional to the temperature and to the current density vector remains in the heat flux density vector. This effect explains, for example, the asymmetry of heat fluxes in the electrodes of a continuously operated electromagnetic accelerator (1).We shall consider this situation in relation to the example of a fully ionized quasineutral gas with identical electron and ion temperatures.     

Density and total pressure behavior in the process of forced and spontaneous reconnection

The specific features of the density and total pressure (the sum of magnetic and gas-kinetic pressures) behavior in the process of forced (by the example of propagation of a magnetic acoustic wave in the vicinity of the X-point) and spontaneous (by the example of development of a helical Thirring mode) reconnection are considered. It is shown that the total pressure distribution depends weakly on the initial value of the gas-kinetic pressure, the strength of the z-component of the magnetic field, and the thermal conductivity in a wide range of parameters. The character of density distribution is determined only by the thermal conductivity. It is also shown that the behavior of the total pressure and density in the case of spontaneous reconnection weakly depends on the thermal conductivity, in contrast to the forced case. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 4, pp. 11–15, July–August, 1999.     

开式热沉内冷刀具的设计及其导热性能分析

车削加工温度对工件的表面加工质量和刀具的使用寿命具有重要影响. 设计了一种开式热沉内冷刀具,计算了在实际加工工艺参数下刀具受到的切削力和前刀面上的热流密度,分析了刀具的结构强度;建立了刀具热-流-固耦合温度场模型,探讨了热稳态条件下刀具的温度场分布,以及刀片冷却液流道内热沉数量对刀具导热性能的影响规律,比较了在相同热源条件下开式热沉内冷刀具与其他内冷刀具的导热性能. 结果表明:对于刀片材料为硬质合金YT5的刀具,在热流密度为10 W/mm2的条件下,内置6个热沉的设计方案可获得最佳冷却效果,刀具的最高切削温度控制为187.1 ℃;与其他内冷刀具相比,开式热沉内冷刀具的最高切削温度降低了12.1 ℃.      

Linear Rayleigh-Taylor instability analysis of double-shell Kidder''s self-similar implosion solution

This paper generalizes the single-shell Kidder's self-similar solution to the double-shell one with a discontinuity in density across the interface. An isentropic implosion model is constructed to study the Rayleigh-Taylor instability for the implosion compression, A Godunov-type method in the Lagrangian coordinates is used to compute the one-dimensional Euler equation with the initial and boundary conditions for the double-shell Kidder's self-similar solution in spherical geometry. Numerical results are ob...     

Functional enhancement of a non-equilibrium plasma jet by seeding in the applied magnetic field

The experimental study is conducted to clarify the functional enhancement of a non-equilibrium argon plasma jet by seeding potassium in the applied magnetic field to extend its industrial applications. It is shown that the plasma parameters such as electron number density and electron temperature increase considerably by seeding especially in the applied magnetic field, which results in the easy enhancement of transport properties such as electrical conductivity and electron thermal conductivity. Finally, the infrared thermography is shown to visualize the relative variation of radiative temperature field comparing both with seeding and without seeding.     

Critical parameters of shock waves in a plasma

The critical parameters at which an isomagnetic compression shock occurs are determined using a regular method based on an analysis of the type of singular points of the equations for the structure of standing shock waves propagating at an arbitrary angle to the undisturbed magnetic field in a plasma with finite conductivity and thermal conductivity.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 27–36, March–April, 1976.     

Experimental study of enhanced heat transfer by addition of CuO nanoparticle

An energy storage system has been designed to study the thermal characteristics of paraffin wax with an embedded nano size copper oxide (CuO) particle. This paper presents studies conducted on phase transition times, heat fraction as well as heat transfer characteristics of paraffin wax as phase change material (PCM) embedded with CuO nanoparticles. 40?nm mean size CuO particles of 2, 5 and 10% by weight were dispersed in PCM for this study. Experiments were performed on a heat exchanger with 1.5–10?l/min of heat transfer fluid (HTF) flow. Time-based variations of the temperature distributions are revealed from the results of observations of melting and solidification curves. The results strongly suggested that the thermal conductivity enhances 6, 6.7 and 7.8% in liquid state and in dynamic viscosity it enhances by 5, 14 and 30% with increasing mass fraction of the CNEPs. The thermal conductivity ratio of the composites can be augmented by a factor up to 1.3. The heat transfer coefficient during solidification increased about 78% for the maximum flow rate. The analysis of experimental results reveals that the addition of copper oxide nanoparticles to the paraffin wax enhances both the conduction and natural convection very effectively in composites and in paraffin wax. The paraffin wax-based composites have great potential for energy storage applications like industrial waste heat recovery, solar thermal applications and solar based dynamic space power generation with optimal fraction of copper oxide nanoparticles.