摘要
同轴枪脉冲放电产生的等离子体具有高速度、高密度的特点,在核聚变、空间推进、天体物理领域具有很高的应用价值.本文针对不同放电方式对等离子体特性的影响进行了理论实验研究,通过调换脉冲电源整流二极管的方向改变充电电流方向实现正、负脉冲放电,采用光学、电学、磁探针等诊断手段,研究了正、负脉冲放电产生的等离子体性能;通过高速相机观察到正脉冲等离子体的分团现象,使用了图像处理技术,量化对比了等离子体发光强度.结果表明在相同工作气压和放电电压下,负脉冲等离子体拥有更高的密度,流速稍小但性能趋稳;而正脉冲等离子体具有更高的射流速度,也易产生明显的分团现象,所得实验结果与理论分析相一致.
The coaxial gun plasma generated by pulsed discharge possesses the characteristics of high speed and high density,and has potential application value in the field of fusion,space propulsion and astrophysics.In this paper,the effect of positive and negative pulsed discharges on plasma characteristics are investigated and a theoretical model for analyzing the morphology of positive and negative pulsed current sheets is proposed.Positive and negative pulsed discharges are realized by changing the direction of the rectifier diode in the pulse power supply to change the direction of the recharging current.Through theoretical analysis,and measurements by using photodiode,Pearson probe,magnetic probe,HD camera,fast-framing camera and RGB image processing,the plasmas generated by positive and negative pulsed discharges are compared and investigated.Most of experimental diagnoses concentrate on investigating the plasma behavior in the coaxial gun muzzle on a microsecond-order time scale.Because radial and axial transport characteristics of plasma change little,we think,the plasma characteristics in the muzzle still depend on the characteristics of plasma in the coaxial gun.Therefore,the conclusion of the theoretical analysis of the current sheet in the coaxial gun is still valid for the plasma in the muzzle.The theoretical analysis shows that the positive pulsed current sheet presents a parabolic shape and the negative pulsed current sheet displays a convex shape,which makes the negative pulsed current sheet sweep more efficiently and a large amount of plasma is concentrated near the inner electrode,namely the cathode,so the negative pulsed plasma is denser.For the positive pulsed plasma,near the inner electrode the plasma is thin and the magnetic pressure is powerful,and near the outer electrode,the plasma is dense and the magnetic pressure is weak.Therefore,the positive pulsed plasma is faster in movement speed but easier to split,and because of its dispersion,its transport stability is not so good as that of the negative pulsed plasma.The experimental results accord with the theoretical analyses.The final conclusion shows that under the same discharge parameters,the positive pulsed discharge produced plasma is faster in movement speed but more likely to split,and the negative pulsed discharge created plasma is denser in density and more stable.Therefore,for obtaining a higher density plasma,the negative pulsed discharge is recommended,and for achieving a high-speed plasma source,the positive pulsed discharge is advised to be adopted.
作者
余鑫
漆亮文
赵崇霄
任春生
Yu Xin;Qi Liang-Wen;Zhao Chong-Xiao;Ren Chun-Sheng(Key Laboratory of Materials Modification by Laser,Ion and Electron Beams of Ministry of Education,School of Physics,Dalian University of Technology,Dalian 116024,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2020年第3期215-224,共10页
Acta Physica Sinica
基金
国家重点研发计划(批准号:2017YFE0301206)资助的课题~~
