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.

Figure 2 Effects of the S50del mutation on the transactivation ability and phosphorylation modification of NRL protein. (a) Dual-luciferase reporter assay of the WT and S50del mutant NRL proteins. Relative luciferase activities of the three groups, WT+basic, WT+RHO, and S50del +RHO, were shown as mean ± SD. *Po0.05. (b) Electrophoretic mobility shift assay of the Flag-tagged WT and S50del mutant NRL. Tubulin was used as a loading control. Samples treated with alkaline phosphatase were used as dephosphorylated controls.

As a new additive manufacturing technology, electrostatic printing has the advantages of high resolution, high material applicability and no clogging. The electric field distribution (EFD) has a significant impact on the jet stability and the deposition quality during electrostatic printing microstructures. The distribution characteristics of electric fields were investigated using the finite element analysis software COMSOL Multiphysics in this paper. The distribution patterns of the electric field strength in the printing space were studied. The results show that the EFD in the three-dimension space within 0.5 mm from the nozzle is extremely complex, and jet instability occurs in this region. The influence of micropillar on the changing patterns of EFD was investigated and the self-alignment effect in electrostatic printing was revealed. This result provides an effective analytical tool for electrostatic printing, which is important for improving the regulation level of electrostatic spraying for realizing the controlled microstructures of electrostatic printing.