Numerical simulation of breakdown characteristics of capacitively coupled hollow-cathode discharge

Hollow-cathode discharge (HCD) is widely applied in processes like chemical vapor deposition because its trench structures can enhance ionization and plasma density and promote sputtering. While discharge characteristics have been studied extensively, existing studies on the breakdown phase have predominantly focused on ignition conditions or the evolution of macroscopic parameters. However, there remains limited insight into the spatiotemporal evolution of plasma parameters and the underlying kinetic mechanisms governing the breakdown of radio-frequency (RF) HCDs. In this work, a 2D particle-in-cell/Monte Carlo collision simulation is developed to investigate the breakdown process of RF HCD. Results show that during breakdown, the electron density inside the trench is significantly higher than that in the main chamber, with the density peak appearing at the center of the electrode opposite to the trench. After the breakdown, the electron density peak shifts to the outer side of the trench. Before the breakdown, the electron energy is uniformly distributed with relatively high energy throughout the bulk region; as the breakdown progresses, the energy decreases and becomes concentrated outside the trench. The evolution of other plasma parameters, including the Electron Energy Probability Functions, potential and electrical characteristics, and the transient dynamics during the breakdown process, is also analyzed.