Micro-discharge in tortuous pores: ‘splitting-quenching’ of primary ionization wave and the role of pre-ionization

Porous discharge has been widely studied recent years, however the discharge development inside the pores with complicated structure was little involved. In this paper, the discharge developments in vertical and tortuous pore are studied using a 2D fluid model in Cartesian coordinate system established by COMSOL Multiphysics. The discharge develops symmetrically and bilaterally in vertical pore, and along the higher potential sidewall in tortuous pore, respectively. For tortuous pore, there are two pre-ionization process with negative and positive polarity successively, the latter one splits off from the former one and is in the form of multiple ionizing heads propagating simultaneously in string. The negative one can induce the primary discharge to deflect at the channel elbow joint in a ‘splitting-quenching’ way or directly deflect it by bridging with it. For the positive one, the multiple ionizing heads can distort the electric field and short cut the potential and thus accelerate the primary discharge. Furthermore, the discharge can be enhanced deep inside the tortuous pore by the large number of seed electrons provided by pre-ionization. The influence of the dielectric constant is also studied, with the dielectric constant increases, the discharge can maintain bilateral morphology in tortuous pores for a deeper development distance.