In order to further reveal the characteristics and mechanism of the self-pulsing discharge in cavity cathode discharge

the effect of electrode spacing on the characteristics of cavity self-pulsing discharge is studied experimentally by using the groove cavity electrode structure. At the same time

the fluid model is used to simulate the microscopic dynamics of the cavity discharge breakdown phase. The results show that there is an obvious negative differential resistance phenomenon in the process of self-pulse discharge

and the self-pulsing frequency increases approximately linearly with the increase of average discharge current. The distance between cathode and anode has an effect on the characteristics of self pulsing discharge. With the increase of the gap between cathode and anode

the average sustained voltage and the self-pulsing frequency increase

the peak value current drops

the maximum and the minimum values of self-pulsing voltage increase

and the rising time of self-pulsing increases. The current minimum value does not change with the change of electrode spacing. The simulation results show that the self-pulsing discharge is a periodic conversion process from the discharge mode with low current

low electron density and axial electric field at the orifice of cavity to the discharge mode with high electron density and radial electric field in the cavity. The self-pulsing of cavity cathode discharge can be regarded as a repeated process of net positive space charge layer or virtual anode moving from the orifice to the cavity and then to the orifice of the hole

and the intensity of net positive charge layer first increases

then decreases and then increases. The smaller the gap between cathode and anode is

the more obvious the influence of anode on the cavity discharge will be

the more intense the cavity discharge will be

and the higher the current peak will be. In addition

the results show that the equivalent resistance of the discharge cell is mainly determined by the spatial electron density. The higher the electron density is

the lower the equivalent resistance will be.