Computational analysis of direct current breakdown process in SF₆ at low pressure

Abstract

The breakdown of SF6 gas at low pressure is of vital importance to both aerospace and microelectronics industries. However, the breakdown characteristics of SF6 in direct current at low pressure are still seldom studied. In this work, one-dimensional implicit particle-in-cell/Monte-Carlo collision algorithm is used to study the entire direct current breakdown process of low-pressure SF6. The ion-molecule collision, recombination, and external circuit are considered in the model. According to the results, the breakdown process can be divided into three stages: pre-breakdown stage, breakdown stage, and post-breakdown stage. In the pre-breakdown stage, the cathode sheath is not yet formed so the constant electric field exists in the entire area. In the breakdown stage, the formation mechanism of the cathode sheath is analyzed and the electrodes as a whole changes from capacitive to resistive, sharing the voltage with the external resistance. In the post-breakdown stage, the continued growth of positive ions leads to the formation of a thin anode sheath, which further causes the negative plasma potential, different from electropositive gas. The energy production terms including heating power and secondary electron emission (SEE) power are equal to the energy loss terms including collision loss power and boundary loss power, where collision loss power and boundary loss power are almost equal, while SEE power is negligible. In the final, plasma parameters gradually evolve to the last steady-state.

Numerical characterization of the breakdown process of dc-driven micro-discharges sustained by thermionic emission

“…For DC discharge, a changeable ballast (or current-limiting resistor) is usually used as the external circuit, which is connected in series between the DC power supply and the electrode to protect the whole circuit [35][36][37]. In this work, similar to [37,38], a ballast resistor is used as the external circuit, shown in the left figure of figure 1, which is connected between the negative pole of the DC power source and the electrode of the discharge chamber. The positive pole of the power source and another electrode is grounded.…”

On the breakdown process of capacitively coupled plasma in carbon tetrafluoride

“…Compared to argon, discharges in electronegative gases such as CF 4 are quite different [9,[11][12][13][14]. This has been confirmed by our recent work on dc breakdown in SF 6 [30]. As an important gas used in plasma etching for the semiconductor industry, the breakdown process of CCP discharge in CF 4 has barely been studied yet.…”

Breakdown modes in nanosecond pulsed micro-discharges at atmospheric pressure

“…Grounded in first-principles-based particle kinetic simulation, this method allows larger spatio-temporal steps compared to explicit methods [48,[74][75][76], diagnoses the dynamic breakdown evolution, and records plasma parameter evolution, effectively characterizing non-equilibrium and non-local plasma dynamics. Its effectiveness has been demonstrated in observing parameters governing DC breakdown in SF 6 at low pressure [77] and the breakdown process of DC-driven micro-discharges sustained by thermionic emission at atmospheric pressure [16]. Utilizing the coupled MCC model [78], this approach considers various collision processes, including elastic scattering, excitation, and ionization collisions for both electrons and neutral atoms, charge exchange, and elastic scattering for ions and neutral atom collisions, with cross-sectional data sourced from referenced literature [61].…”