# Investigation of the Opposite-Electrode Effect on the Planar Solid-State Pulse-Forming Line
## 1 Introduction  
With increasing emphasis on health, energy conservation, and environmental protection, pulsed electric field (PEF), a novel and promising technology, is being applied to treat cardiovascular diseases, reduce energy consumption in food processing, and protect the environment [1; 2; 3; 4]. Electroporation is a phenomenon of biological cell membrane permeabilization triggered by a PEF, and it has been widely used for the ablation of tumors and the inactivation of enzymes and microorganisms [5; 6; 7]. The basic principle of the electroporation system is that electrical pulses generated by the pulse generator are applied between two electrodes, thereby producing a PEF with durations ranging from nanoseconds to milliseconds. The pulse generator, as an important component of the electroporation system, can compress a long-duration, low-power input into a short-duration, high-power output, and its performance directly affects the application range of the electroporation system [8; 9; 10].  
Exponential or square pulses are generally used for the electroporation of cells. In laboratory settings, the use of square pulses confers greater advantages [11; 12; 13]. In recent years, pulse power technology has been evolving toward compactness, modularity, and strong environmental adaptability [14; 15; 16; 17; 18]. This evolution provides more possibilities for manufacturing pulse power devices that can generate square pulses to satisfy the demands of electroporation systems. The pulse-forming line (PFL) is a critical component in pulse power systems for generating high-power quasi-square wave pulses that has also been developing toward solid-state and compactness in recent years [19; 20; 21].  
Ceramic dielectrics, with their high relative dielectric constant and insulation strength, as well as their modular and environmentally adaptable features, have become an important alternative to liquid dielectrics for the construction of the PFL [22; 23; 24; 25; 26]. Stack-line-type pulse generators represent a crucial application scenario for a solid-state PFL. A pulse generator using this technology route can output square pulses, and the system parameters can be flexibly adjusted by changing the solid-state PFL and the number of cascaded stages. A stack-line-type pulse generator using a solid-state PFL has the advantages of high power, compactness, and robustness and has broad application prospects in the field of electroporation. To ensure optimal system performance, it is imperative to focus on developing a solid-state pulse-forming line with low characteristic impedance, high-quality square wave output, and higher withstand voltage strength [27].  
A number of researchers have conducted comprehensive studies on the PFL, utilizing ceramic dielectrics, encompassing the fabrication of a planar solid-state PFL [28], the determination of characteristic parameters [29], and the analysis of waveform quality and withstand voltage strength [27]. At present, the predominant configuration for a planar solid-state PFL features a full-electrode structure for the ground electrode and a curved electrode structure for the high-voltage electrode (full-electrode PFL). The results of investigations have revealed that insulation failure leading to breakdown or surface flashover in a planar solid-state PFL typically occurs at specific locations and may be associated with thermal effects within the PFL [19].  
In this work, we explored how the ground electrode structure affects the edge electric field of the high-voltage electrode and designed an opposite-electrode PFL with a lower edge electric field based on the opposite-electrode effect on the planar solid-state PFL. Furthermore, we conducted an experimental comparison of the withstand voltage and thermal characteristics between the opposite-electrode PFL and the classic planar solid-state PFL.