DTR27TZ02-NV003 — Compact High Energy Density Capacitors For Pulsed Field X-Ray Generators

DTRA seeks ultra-compact, high-voltage, high energy density, capacitors and related advanced dielectric materials to support the development of advanced portable X-ray radiographic imaging systems.

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.

Conceptualizing capacitor design type and proof of principle of manufacturing process. In Phase 1 of this effort, a suitable capacitor type and design will be chosen to meet the above-listed performance parameters. This decision should be informed by extensive modeling, simulation, and market research, and guided by availability of materials needed. Preference is indicated for domestically available materials. Note that while temperature and vibration ruggedization are to meet MIL-STD ranges, formal testing and certification to the MIL-STD specifications is not required during this phase. Following the design decision, material samples will be fabricated and tested to validate performance. Evaluation of success will be weighted towards feasibility of materials to achieve the highest priority specifications: operating voltage and voltage reversal. Additionally, the offerors will define a detailed plan for a scalable prototype manufacturing process to be executed in Phase II, including equipment needs, quality control steps, and risk mitigation. The designed process should demonstrate progress towards production of capacitors that meet the defined performance criteria with particular attention to overcoming the miniaturization and reliability challenges associated with scaling from larger directed energy capacitor designs. The Phase 1 final report should include: details for chosen capacitor design along with relevant modelling, simulation, and market research results, details of the chosen manufacturing process, and test and evaluation results of the proof-of-principle capacitor performance (including but not limited to voltage reversal testing representative of Marx generator operation) and percentage of fabricated material samples that meet specifications via the initial process.

Manufacturing process execution, refinement, and scaling up of output. In Phase 2 of this effort, the manufacturing process designed in Phase 1 will be executed, refined, and scaled up with the goal of reliable capacitor output with high percentage of capacitors meeting performance specifications. The goal of this phase of the effort should be a manufacturing process with output and reliability of produced components that meet a TRL 5. The final report for Phase 2 will include final details of the optimized manufacturing process and throughput, output capacitor specifications, and percentage of output that meets design specifications. Capacitors will be delivered to DTRA by the end of Phase II for evaluation in a representative pulsed power system for X-ray generation, as follows: • Year 1: Fabrication of 10 prototype capacitors for testing, validation and refinement. • Year 2: Final deliverable of up to 10 fully compliant prototype capacitors to DTRA.

Optional phase that will continue scale up and output of capacitor manufacturing process. The goal of this phase 3 work will be to produce capacitors that exceed the above listed performance specification and continue to increase the output of capacitor manufacturing while maintaining high-percentage of capacitors meeting performance specifications.