Traditional high-powered cathode electron emitter-based equipment for high-bandwidth communications, security screening or imaging applications can run hot, significantly shortening the lifespan and usefulness of the equipment.
A new program from the Defense Advanced Research Projects Agency called Advanced Cathode Development is looking to remedy that situation by developing what the agency calls "cold" cathode electron emitter technology that "can operate at a temperature of less than 1000 °C. The cathodes also should be sufficiently mechanically robust to withstand operation in a power tube environment and capable of being fabricated in form factors suitable for compact, high power, high frequency vacuum electronics devices."
"Current state of the art cathodes for high frequency vacuum electronics must operate at high temperatures to provide sufficient beam current at suitably high current density. These requirements significantly increase the design complexity for the device including the thermal management, magnetics, and component configuration. These requirements also can lead to diminished lifetime, additional weight, and undesirable compromises in overall performance," DARPA said.
The agency has pinged the industry with a Request for Information (RFI) on the subject and says it is interested in learning about four key components of such revolutionary cathode development including:
1. Operating Temperature: Of interest are cathodes that operate at temperatures at or below 1000 °C. It is encouraged that submissions describe the effect of operating temperature on relevant parameters such as total current, current density, and lifetime.
2. Current and Current Density: Of interest are cathodes that provide total current of at least 10 mA at a current density of at least 1 A/cm2. It is encouraged that submissions describe the expected theoretical and practical maximums and tradeoffs of their cathode technology with respect to these metrics.
3. Lifetime: Of interest are cathodes that can provide the stated current and current density for at least one hour of CW operation. Submissions should describe the effect of temperature, current, and current density on the lifetime as well as describing the expected failure mechanisms of the cathode.
4. Fabrication: In addition to performance, this RFI also seeks to understand the fabrication process of the cathodes and its scalability to commercial manufacture. Additionally, submissions should discuss the development risk of the concept and measurable progress milestones to enable accurate estimation of the resources and time frame necessary to pursue these cathodes.
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