International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Plasma-based ion implantation (PBII) is a surface modification technique that applies a negative high-voltage pulse to a sample immersed in plasma. PBII is suitable for samples with complex geometries, as its ion sheath conforms to the sample’s shape, ensuring uniform ion implantation. Due to its precise controllability, PBII is widely used industrially for surface modification and has promising applications for sterilization. We previously used PBII with oxygen gas to successfully sterilize heat-resistant spore. Here, we evaluated the use of PBII with HHO as the process gas for sterilization. Sterilization exceeding 7D was achieved at 10 min and 3 Pa. The enhancement of the sterilization efficacy was attributed to the synergistic effect of plasma and thermal energy, which emerged as a consequence of a temperature increase exceeding 100°C due to adjustments in pulse width and delay time. These results indicate the possibility for temperature control in PBII technology, which has potential application in sterilization processes.

The electric potential distribution is critical in Plasma-Based Ion Implantation (PBII), as it directly influences the energy and spatial distribution of implanted ions. Understanding the effects of key parameters, such as the applied voltage and gas pressure, on the formation of the electric potential distribution is essential for optimizing PBII-based sterilization. In this study, plasma simulations were conducted using PEGASUS (PEGASUS Software Co., Ltd.) to examine variation in the electric potential distribution under different operating conditions. The analysis focused on changes in the electric potential distribution and ion density in response to variations in the applied voltage. The results indicated that, increasing the applied voltage, led to an expansion of the negative potential region to approximately −500 V, highlighting the role of positive ions play a key role in the sterilization process. Furthermore, enclosing non–sample areas with a grounded structure reduced unnecessary plasma generation, potentially improving energy efficiency during sterilization experiments.