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Discharge Feature and Acceleration Mechanism of Magnetoplasmadynamic Thrusters

磁等离子动力推进器的放电特性及加速机制

基本信息

批准号：
04452112
负责人：
YOSHIKAWA Takao
金额：
$ 4.35万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

Quasisteady magnetoplasmadynamic thrusters with applied magnetic fields were studied to clarify the influence of axial magnetic fields on the thruster performance and the discharge feature and to understand the acceleration mechanism. The main power-supplying pulse forming network (PFN), which was capable of storing 62 KJ at 8 KV, delivered a single nonreversing quasisteady current of maximum 27 KA with a pulse width of 0.6 msec. A vacuum tank 5.75m in length and 0.6m in diameter, where the thruster fired, was evacuated to some 10^<-3> Pa prior to each discharge. Pulsed axial magnetic fields were applied by a few-turn coil, which was connected with a PFN independent of the main discharge circuit. An increase in axial field strength raised the discharge voltages at constant discharge currents below the limiting current with H_2, mixture of N_2+2H_2 and Ar. The thrust characteristics for H_2 and mixture of N_2+2H_2 showed that there was the optimum axial field strength with which the maximum thrust was achieved for each gas, although at low discharge current levels for H_2 and Ar the thrusts increased with axial field strength. The discharges for all gases were inclined to occur more upstream with an increase in axial field strength, resulting in broad high-temperature distributions in the discharge chamber. It was inferred that these effects of axial magnetic fields on the thruster performance and the arc feature were due to rotating motion of -J_rxB_z, that is, swirl acceleration and enhanced thermalization.

为了阐明轴向磁场对磁等离子体动力学推力器性能和放电特性的影响，并了解其加速机理，对外加磁场的准稳态磁等离子体动力学推力器进行了研究。主电源脉冲形成网络（PFN），这是能够存储62千焦在8千伏，提供了一个单一的非反向准稳态电流的最大值为27千安培的脉冲宽度为0.6毫秒。一个长5.75米，直径0.6米的真空罐，在推进器点火的地方，在每次放电之前被抽空到大约10^<-3>Pa。脉冲轴向磁场由一个少匝线圈施加，该线圈与独立于主放电电路的PFN相连。在H_2、N_2+2H_2和Ar的混合气体中，轴向场强的增加使放电电压在低于极限电流的恒定放电电流下提高。H_2和N_2+2H_2混合气体的推力特性表明，存在一个最佳的轴向场强，在此场强下，每种气体的推力都达到最大值，但在低放电电流水平下，H_2和Ar的推力随轴向场强的增加而增加。所有气体的放电倾向于发生更上游的轴向场强的增加，导致广泛的高温分布在放电室。轴向磁场对推力器性能和电弧特性的影响是由于-JrxBz的旋转运动，即涡流加速和热化增强所致。