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The intersection point of the characteristic magnetic field line (CMFL) crossing the anode boundary with the discharge channel wall,and its influence on thruster performance and the energy and flux of ions bombarding the channel wall,have been studied numerically.The simulation results demonstrate that with the increase in distance from the crossover point of the CMFL with the channel wall to the bottom of the thruster channel,the ionization rate in the discharge channel gradually increases;meanwhile,the ion energy and ion current density bombarding the channel wall decreases.When the point of the CMFL with the channel wall is at the channel outlet,the thrust,specific impulse,and efficiency are at a maximum,while the ion energy and ion current density bombarding the channel wall are at a minimum.Therefore,to improve the performance and lifetime of the thruster,it is important to control the point of intersection of the CMFL with the channel wall. 相似文献
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综采放顶煤工作面上覆岩层的破坏和冒落是一个复杂的力学过程。用相似材料模拟试验法,对放顶煤开采上覆岩层运动和矿压显现规律进行研究,得出了上覆岩层运动特点和工作支承压力分布规律,并对顶煤破碎与支承压力的关系进行了分析,为工作面矿压控制参数选择提供了依据。 相似文献
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潘津煤矿煤层较厚且易自然发火,设计采用综采放顶煤采煤法。为了有效防止采煤工作面自然发火,通过对综放工作面煤层自燃特点的分析,提出了预防性灌浆、注氮、喷洒阻化剂、均压防灭火、地面填埋堵漏和监测监控等防灭火综合措施,为矿井生产中防灭火措施的选用提供了借鉴。 相似文献
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Haotian FAN 《等离子体科学和技术》2022,24(2):24001
In this study, the neutral gas distribution and steady-state discharge under different discharge channel lengths were studied via numerical simulations. The results show that the channel with a length of 22 mm has the advantage of comprehensive discharge performance. At this time, the magnetic field intensity at the anode surface is 10% of the peak magnetic field intensity. Further analysis shows that the high-gas-density zone moves outward due to the shortening of the channel length, which optimizes the matching between the gas flow field and the magnetic field, and thus increases the ionization rate. The outward movement of the main ionization zone also reduces the ion loss on the wall surface. Thus, the propellant utilization efficiency can reach a maximum of 96.8%. Moreover, the plasma potential in the main ionization zone will decrease with the shortening of the channel. The excessively short-channel will greatly reduce the voltage utilization efficiency. The thrust is reduced to a minimum of 46.1 mN. Meanwhile, because the anode surface is excessively close to the main ionization zone, the discharge reliability is also difficult to guarantee. It was proved that the performance of Hall thrusters can be optimized by shortening the discharge channel appropriately, and the specific design scheme of short-channel of HEP-1350PM was defined, which serves as a reference for the optimization design of Hall thruster with large height–radius ratio. The short-channel design also helps to reduce the thruster axial dimension, further consolidating the advantages of lightweight and large thrust-to-weight ratio of the Hall thruster with large height–radius ratio. 相似文献