Effect of external electric field on helix plasma plume

The helix plasma was found in a sealed quartz tube with/without a helical coil on the outer surface of the quartz tube before. The reason for the helix structure of the plasma is unclear. In this paper, an additional high voltage pulsed DC power supply is applied to the external helical coil to control the helix plasma inside the tube. The parameters of the additional power supply including the amplitude, the phase difference, the pulse width and the repetition frequency are adjusted. It was found that, when the voltage of the additional power supply is adjusted to 1.8 kV, the helix plasma plume looks like the original helix plasma without helical coil. However, their propagation speeds for the two cases are significantly different. In addition, when the pulse width and the repetition frequency of the voltage on the helical coil are adjusted, several interesting behaviors of the plasma plume are observed. Finally, an equivalent circuit model for the plasma propulsion process with the additional helical coil is presented considering the long discharge circuit as numerous capacitances and resistances series-parallel connected and the propagation process of the long plasma plume as the process of charging the paralleled capacitances. It is believed all the results discovered in this paper are helpful for better understanding of the mechanism of the helix plasma. (paper)