共查询到19条相似文献,搜索用时 109 毫秒
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采用一维流体模型研究了含有杂质离子的等离子体与器壁材料相互作用给边界等离子体参量带来的影响.通过数值模拟,研究了分别选用碳和钨作为器壁材料时,器壁温度不同情形下热发射产生的电子对等离子体器壁电势、电场强度、热发射电子流以及沉积器壁离子动能流的影响.研究结果发现,当面向等离子体材料表面温度升高时,器壁电势和热发射产生的电流将增加,器壁电场强度和离子沉积器壁动能流则会减小,并且钨作为器壁材料要比碳作为器壁材料对于等离子体边界参量影响更明显.此外,研究了钨作为器壁材料时,碳杂质离子(浓度和电荷数)对等离子体器壁参量的影响. 相似文献
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利用数值计算与粒子模拟两种方法,结合实际的实验数据,对高功率微波二极管中相对论电子束与背景气体相互作用碰撞产生的等离子体密度进行了研究.研究结果表明:碰撞产生的等离子体密度数值计算结果与粒子模拟结果基本一致,背景气压在0.01 Pa—0.05 Pa时,碰撞产生的等离子体密度在4—12×109cm-3,即便在考虑电子离子复合的情况下,数值计算结果与粒子模拟结果依然符合得很好.另外,粒子模拟结果表明:随着气压的增加,等离子体密度呈现先增大再减小然后又逐渐增大的过程,
关键词:
相对论电子束
等离子体
数值计算
粒子模拟 相似文献
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本文用数值模拟法,通过数值求解二维多流体等离子体输运方程。来模拟托卡马克边界等离子体输运过程和输运特性。模拟计算的结果,对托卡马克偏滤器和第一壁的设计有重要意义。 相似文献
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针对水陆两栖飞机静水面高速滑行过程的运动响应大、流场强非线性等问题,提出了一种基于传统动网格技术的"状态预估——精确计算"的数值模拟方法:通过求解Reynolds平均N-S方程结合运动方程来模拟飞机静水面滑行时的流场特征和运动特性,数值模拟方法为隐式有限体积法,湍流模型采用k-ω(SST Menter)结合壁函数进行处理,自由液面捕捉采用VOF方法;数值计算时,首先采用粗网格对简化后的飞机在不同航速下的姿态和升沉进行快速预估,再将飞机置于预估状态下进行精确网格划分,最后进行精确数值计算分析.为了验证数值模拟结果的正确性,在物理水池中进行了静水拖曳试验,将数值计算结果与试验结果进行对比分析可得:数值计算与水池试验的流场特征吻合,且阻力、姿态和升沉的计算精度达到90%,验证了数值模拟方法的可行性. 相似文献
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本文用数值解二维流动与传热椭圆型方程组的办法,在1000-3000K的范围内研究了壁温对高温电离气体绕流圆拄体传热、阻力与前驻点压力的影响。计算中采用了实际的氩等离子体物性和SIMPLER算法。计算结果表明,尽管壁温下的热物理性质数值有几倍的变化,传热量、阻力系数及前驻点压力变化不大,动量与热量交换过程主要取决于来流参数而不是壁面参数。壁温变化时,壁面处气体的温度梯度与速度梯度大小发生相应变化,流动分离点及局部传热率最低的位置也略有变化。 相似文献
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Thornhill L.D. Batteh J.H. Littrell D.M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1989,17(3):409-421
A model is developed for investigating the performance of solid, plasma, hybrid, and transitioning armatures as a function of railgun geometry and gun operating conditions. The two figures of merit used in the calculation are the armature efficiency and the maximum velocity. Effects investigated include armature parasitic mass, armature resistance, friction, ablation drag, and, for the hybrid armature, gap growth. The model is applied to study how armature performance scales with projectile mass, or correspondingly bore dimension, and with gun current per unit rail height in the hypervelocity regime from 7 to 15 km/s. The model indicates that armature efficiency generally increases with projectile mass, whereas the maximum velocity for plasma and transitioning armatures is relatively insensitive to projectile mass. Calculations are also performed to determine the sensitivity of the model's predictions to uncertainty in key parameters, such as the ablation entrainment fraction, the skin friction coefficient, and the contact potential 相似文献
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电磁轨道发射的过程中,电枢在膛内高速运动时会受到电磁力、电枢初始正压力、摩擦力、空气阻力、烧蚀阻力等多种因素影响,电枢的出口速度呈现出在一定范围内波动的特征。为了提高电枢的出口速度精度,针对膛内电枢与轨道摩擦不均衡性和烧蚀程度不确定的特性,综合考虑脉冲成形网络的电路模型与电枢的动力学特征,建立了电枢在膛内的运动开环控制仿真模型。通过仿真,得出了脉冲电源模块触发时刻与电枢出口速度之间的关系,提出了电枢出口速度闭环控制模型,探究了电枢出口速度控制可行方案。结果表明:应用闭环控制算法,可实现对电枢出口速度的精确控制。 相似文献
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现有的“E”型平衡电枢等效磁路模型仿真研究通常不考虑金属外壳磁阻带来的影响。为了解决平衡电枢换能器中因金属外壳和平衡电枢紧密接触带来的非线性磁阻问题,在现有的平衡电枢换能器等效磁路模型上加入了外壳磁阻影响。分析等效磁路模型磁通部分和力学部分的状态空间方程在不同参数条件下的仿真结果,总结不同参数对该模型阻抗和振膜位移的影响情况。通过仿真对比,外壳磁阻对平衡电枢换能器位移频率响应曲线的影响为1~3 dB。对于组装后包含金属外壳的平衡电枢耳机、助听器产品降低频率响应曲线偏差具有一定的指导意义。 相似文献
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Azzerboni B. Becherini G. Cardelli E. Tellini A. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1989,17(3):463-467
The behavior of the electromagnetic and thermal quantities in a plasma arc placed between two conducting rails is analyzed. The plasma hydrogen drives the hydrogen pellets for the refueling of magnetic fusion reactors. Considering the general equations of electromagnetism and of plasma fluid dynamics and assuming steady-state conditions in a frame which is moving at the same rate as the plasma arc armature, a one-dimensional model is deduced. The effects of an applied magnetic field on the behavior of all flow variables are investigated. Results indicate that the adverse effects of plasma arc heating can be reduced by the application of a magnetic-induction field normal to the current path in the armature. At the maximum acceleration pressure (30 bar) applicable to the hydrogen pellet in the proposed one-dimensional model, the arc temperature at the pellet backend falls from 20000 to 14000 K when a magnetic induction of about 5 T is applied 相似文献
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针对轨道炮电枢出炮口时拉弧问题,提出了一种基于分流器形式的炮口电弧抑制方案。以固体电枢为研究对象,采用Simulink软件根据发射器与消弧装置的电气参数建立含有炮口消弧装置的发射系统仿真模型,目的是通过对消弧装置电气参数不同阻抗值的仿真计算,实现消弧装置电气参数与发射系统电气参数的最佳匹配,达到降低消弧支路对电枢出炮口速度的影响,同时有效地抑制炮口电弧。由于与消弧装置串联的电枢前方轨道阻抗在消弧支路阻抗中占比很大,通过消弧装置阻抗电阻、电感优化调整,实现电枢在膛内运动起始阶段,消弧支路的阻抗远大于电枢支路的阻抗,发射电流大部分都流过电枢,保证了电枢的加速运动。随着电枢向炮口方向运行,消弧支路阻抗快速减小,同时在磁通压缩作用下,消弧支路中电流快速增加,电枢支路电流减小,但由于电枢前后方磁场对其都是推进作用,电枢出炮口速度基本不受影响,保持较高的系统效率;电枢出炮口后,消弧支路的阻抗小于电弧的阻抗值,建立合理的电弧快速消引条件,消弧支路电流远大于电枢上电流,发射系统的剩余能量可通过消弧装置释放,降低炮口拉弧对发射性能的影响。经过消弧装置的电阻和电感多参数值的计算与分析,最后确定与文中发射系统匹配的消弧装置电阻约为1 mΩ,电感约为0.1 μH。结合发射装置结构,设计出的消弧装置电阻为1.32 mΩ,电感为0.124 μH,在搭建的发射系统仿真模型中对其进行了充电电压3 kV等级的发射仿真计算,在充电电压3 kV的发射能量等级下进行了消弧发射试验,仿真结果与试验结果具有较好的一致性,消弧效果良好。 相似文献
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Thornhill L.D. Batteh J.H. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1993,21(3):289-297
A methodology for deriving the electrical and thermodynamic properties of plasma armatures in railgun launchers is presented. The methodology is based on the solution to the one-dimensional, quasi-steady equations for the plasma armature. It is shown that the thermodynamic and transport properties for typical armature materials can be adequately represented by power-law curve fits in the temperature and pressure regimes of interest. To illustrate the methodology, detailed computations for both copper and aluminum armatures are performed. Some discussion is also presented for hydrogen armatures. It is shown that the armature properties predicted by the scaling laws agree very well with those derived from more detailed numerical solutions to the governing differential equations. It is shown that, for both aluminum and copper armatures, the electrical conductivity is a strong function of the current per unit rail height and a weak function of launcher geometry. This dependence is shown to be in reasonable agreement with experimental data compiled over a wide range of gun bore dimensions and operating conditions 相似文献
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Sedghinasab A. Keefer D.R. Crowder H.L. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1989,17(3):360-364
Quartz optical fibers have been used to obtain quantitative, time-integrated, high-resolution, in-bore spectra from a plasma-armature railgun. The observed spectrum consists primarily of continuum radiation, and the only significant spectral features are resonant absorption lines. A detailed plasma-radiation model was used to predict the spectrum in the region of the absorption lines, providing an estimate for the concentration of aluminum and copper in the plasma. This model was also used to estimate the temperature profile of the armature. A reasonable agreement between the model and the observed spectrum yielded a concentration of 10% aluminum and 10% copper in the armature, with a centerline plasma temperature of 20000 K 相似文献