## 1 Introduction  
Electromagnetic launching technology can solve many bottleneck problems encountered in the development of traditional artillery. It is a critical area of focus for the advancement of future military technology and is increasingly becoming a leading research field in various countries [1]. The synchronous induction coil launcher, when operating in multiple stages, functions similarly to a linear synchronous motor. The current on its armature is induced by the synchronous pulse discharge of the multi-stage drive coils [2]. Researchers have primarily enhanced the launching performance of the device by adjusting the parameters of the launching device, driving power supply, and trigger parameters [3; 4; 5]. In recent years, it has been discovered that the magnetic field distribution produced by introducing reverse current into one or multiple drive coils improves the final exit velocity and energy conversion efficiency. As a result, researchers have initiated studies on introducing different current directions into the drive coils, both domestically and internationally. Earlier, the Sandia National Laboratories in the United States discovered that changing the arrangement of the adjacent drive coils' polarity in the multi-stage SICL could enhance the launching performance. [PERSON] et al. initially proposed two different energization methods to address this phenomenon [6]. These methods involve passing current in the same direction or alternating reverse direction in the drive coils, referred to as the PP launcher and PN launcher, respectively. They concluded that the PN launcher, by adjusting the armature trigger position, would provide a higher armature velocity. Similarly, [PERSON] et al. suggested that it is feasible to change the magnetic field direction to improve the system's launching performance, which was verified by a 15-stage coil gun [7]. From the perspective of the armature acceleration mechanism, they analyzed the armature movement law and current distribution under two magnetic field directions and proposed that the armature acceleration mainly occurs during the falling edge of the drive coil current [8; 9; 10]. [PERSON] et al. improved the energy conversion efficiency by delaying the polarity reversal of the coil to reduce the larger braking force caused by the polarity reversal process [11]. [PERSON]'s team analyzed and explained the reasons why the optimal armature position in each stage coil of the PP and PN configurations is different and why the PN launcher achieves a higher launching velocity [12]. Some researchers have observed that using the PN configuration energization method can enhance the launch performance of the coil device. However, there is currently no explanation within the known scope regarding when to choose the PN configuration and whether it is suitable for all devices [13]. Building upon previous research, this article conducts an in-depth study on the PN configuration of the SICL, which alternately introduces currents of different directions into each stage drive coil. Through finite element simulation analysis, the launch performance differences between the PP and PN energization methods are compared. It is worth noting that during the simulation optimization process of different parameter devices, it is discovered that introducing reverse current into the drive coils alternately can have varying effects on the acceleration performance of the adjusted device. This means that after optimization adjustments, the phenomenon of the PP configuration being superior to the PN configuration arises, and not all devices will achieve better performance under the optimized PN configuration. Researchers have previously focused on the study of PN configuration launch devices based solely on the results obtained from their own device parameters. While researchers like [PERSON] and [PERSON] et al.