High-Voltage Isolated Gate Power Supply for Pulsed Carbon Nanotube X-Ray Systems

This study presents a high-voltage isolated gate power supply for pulsed carbon nanotube (CNT) X-ray systems. The proposed design delivers gate voltages in the kilovolt range relative to a cathode voltage of tens of kilovolts, enabling the bipolar operation of CNT X-ray tubes. To ensure high-voltage insulation, a double-isolated transformer-based converter was employed, accompanied by a method to mitigate the inherent voltage imbalance in such transformers. The system was optimized for rapid voltage transitions, with fast rise and fall times critical for pulsed X-ray generation. An integral–proportional (IP) controller was implemented to achieve fast and stable gate voltage rise, overcoming limitations associated with the characteristics of CNT X-ray tubes. To further minimize fall times, an active pull-down circuit featuring multiple series-connected semiconductor switches was developed. A high-voltage cable-based electromagnetic driving system was implemented to realize high-voltage insulation, synchronous operation, and reliable power delivery to the switches. The experimental validation was conducted with a gate power supply system operating at a tube voltage of 160 kV, using both a resistive load and a CNT X-ray tube. The results demonstrated the system’s ability to deliver stable gate voltages of up to 5 kV at 200 Hz, achieving a rise time of 320 $\mu $ s and a fall time of 60 $\mu $ s under high-voltage conditions. These findings demonstrate the system’s potential for reliable operation in advanced CNT X-ray applications, contributing to the development of high-performance pulsed X-ray systems.