放电参数对同轴枪中等离子体团的分离的影响

Influence of discharge parameters on blow-by in a coaxial plasma gun

同轴枪中的等离子体团的分离现象主要是由同轴枪内磁场的梯度造成的电流层倾斜而引起的一个增强反馈过程导致的,这种分离现象越来越成为限制同轴枪有效使用的一个不利因素.在实验上研究放电参数对等离子体团的分离的影响,对理论研究和实际应用都具有重要意义.在实验中发现,利用光电倍增管可以直接观察到等离子体团的分离程度,由此可以研究放电参数对等离子体团的分离的影响.本实验主要研究电容充电电压、电容、放电气压这三个参数对分离现象的影响.实验发现,分离程度随着电容以及其充电电压的增大而增强,随着气压的增大而减弱.实验结果基于雪犁模型进行分析,电容以及电容充电电压的增大使放电电流增强使磁场梯度增大而导致电流层的倾斜程度增加,而使等离子体团的分离程度变严重,相反,气压的增加使需要加速更多粒子而导致电流层的倾斜程度减弱,而使等离子体团分离程度减弱.分析认为,通过控制在加速过程中影响电流层倾斜程度的因素可控制共轴枪中等离子体团的分离程度.

The blow-by which occurs in a coaxial plasma gun is the result of reinforcing feedback caused by the gradient of magnetic field and the component of axial current due to the canting of current sheath. The blow-by has become a serious negative effect which limits the effective use of the coaxial plasma gun, so it is necessary to study by experiment the parameters that influence the degree of blow-by. This will not only contribute to the study of the theory and mode about blow-by but also give advices to the weakening or eliminating blow-by by choosing suitable parameters in engineering field. The degree of blow-by can be observed directly by photomultiplier, and the influence of voltage of capacitance,capacitance, and the pressure of gas on blow-by have also been studied. It is shown that the blow-by would become more serious with the increase of capacitance or the voltage of capacitance while it becomes weaker with the increase of gas pressure. These phenomena can be explained based on the snowplow model. We consider that the increase of capacitance or the voltage of capacitance can make the current sheath canting more serious, however it would reduce the degree of current sheath canting with the increase of gas pressure. So the blow-by can be controlled by the parameters which influence current sheath canting.