Compact High Energy Density Capacitors For Pulsed Field X-Ray Generators

High energy density capacitors and their constituent dielectrics are vital components for multiple DoW capability needs for high voltage power supplies, Marx generators, high-power microwave sources, and other pulsed-power technologies. The Missile Defense Agency, ONR, NASA and other government agencies have funded efforts into high energy density capacitors for a variety of applications.1 However, it is still very challenging to fabricate high energy density capacitors that reliably meet ultra-compact size constraints for miniaturized high voltage pulse power applications and in a ruggedized field-use system. Recent prototype development of compact pulsed X-ray generators for portable radiographic imaging applications has underscored the difficulty of scaling capacitor technologies originally developed for larger directed energy and pulsed power systems down to the ultra-compact sizes needed for man-portable or small unmanned systems. Key challenges include preserving dielectric performance and high-voltage hold-off at reduced dimensions, achieving robust voltage reversal tolerance essential for Marx generator topologies, maintaining long operational lifetimes under pulsed conditions with repetition rates up to 100 Hz, and attaining high manufacturing yields with consistent quality for reliable field deployment. This topic specifically targets the development of reliable fabrication processes and advanced dielectric materials to overcome these miniaturization and ruggedization barriers for X-ray generator pulsed power applications. DTRA seeks to develop reliable and efficient fabrication and production processes for compact high energy density capacitors. The solution must meet the following minimum specifications: • Outer Dimensions: No larger than 2 inches x 1 inch x 0.5 inch • Voltage Rating: 100kV* • Capacitance: ≥ 2nF • Voltage Reversal Tolerance: 80%* • Operating Environment: Dielectric Liquid or Pressurized Gas (e.g., such as SF6) • Operating Temperature: Capable of meeting MIL-STD • Ability to survive commercial requirements for shock and vibration (i.e. rough handling) • Lifetime: Greater than 100,000 full-charge cycles • Duty cycle: Up to 100 Hz • Charge/Discharge time: Charging order of 10s of microseconds, discharge order of few nanoseconds *Note: Operating voltage and voltage reversal are the highest priority specifications. DTRA may consider small deviations from the other minimum specifications (e.g. size) if the solution is capable of approaching or meeting the objective voltage and voltage reversal specifications below. Objective specifications: • Voltage Rating: 250kV • Capacitance: ≥ 10nF • Capacitance Tolerance: ±10% • Voltage Reversal Tolerance: 100% • Operating Temperature: Capable of meeting MIL-STD • Vibration: Capable of meeting MIL-STD • Lifetime greater than full-charge 1,000,000 cycles This effort shall develop a reliable manufacturing process for high energy density capacitors while maintaining the performance parameters outlined above. The proposed effort will require that developed capacitors be tested and validated in Phase 2.