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Innovative Fabrication Techniques for Millimeter-wave Linear Beam Vacuum Electron Devices

Description:

OUSD (R&E) MODERNIZATION PRIORITY: Cybersecurity, Directed Energy (DE), Microelectronics, Networked Command, Control, and Communications (C3), Space TECHNOLOGY AREA(S): Electronics, Materials/Processes OBJECTIVE: Develop new design, fabrication, alignment, and assembly techniques to significantly reduce the cost and time of manufacturing high power, linear beam VE devices, increase the overall manufacturing yield, and reduce the dependence on skilled touch-labor for the precision fabrication and assembly of devices, particularly at millimeter-wave frequencies. Develop new design, fabrication, alignment, and assembly techniques to significantly reduce the cost and time of manufacturing high power, linear beam VE devices, increase the overall manufacturing yield, and reduce the dependence on skilled touch-labor for the precision fabrication and assembly of devices, particularly at millimeter-wave frequencies. DESCRIPTION: A linear beam vacuum electron device converts the kinetic energy of a longitudinally-streaming electron beam (or multiple parallel beams) into radio-frequency (RF) energy through the interaction with an electrodynamic structure. The electron beam is immersed in an externally-generated magnetic field and the “spent” beam is deposited in an electron collector. The entire device operates in hard vacuum, typically <10-9 torr. Current VE manufacturing practices are labor-intensive, requiring many processing steps and highly-skilled touch labor at each step along the way. At millimeter-wave frequencies, the tight fabrication and alignment tolerances stress the limits of conventional manufacturing practices. This SBIR program seeks to develop new approaches to the design, fabrication, alignment, and assembly of millimeter-wave linear beam VE devices to decrease production cycle times, increase manufacturing yields, and reduce costs. A key goal is to develop new, readily reconfigurable methods of building VE devices that can reduce the time and cost of fabrication by a factor of 10 or more. Technologies of interest include, but are not limited to, advances in materials; CAD/CAM; subtractive, additive, and/or hybrid manufacturing; precision self-assembly and alignment; robotics and automation; and automated inspection and characterization. Novel methods of machining, forming, joining, and assembling materials that are commonly used in VE devices – such as refractory metals, oxygen-free high conductivity copper, high voltage ceramics, and high energy product permanent magnets – are of particular interest. PHASE I: Phase I is a 10-month program to develop the designs and process flows leading to the fabrication (in Phase II) of a proof-of-concept W-band (75-110 GHz) linear beam VE amplifier comprising a thermionic electron gun, beam-wave interaction circuit, and an electrically-isolated electron beam collector. Table 1 summarizes the minimum performance parameters of the amplifier. The object of this SBIR is not to create a new breakthrough W-band device. Rather, the W-band VE amplifier will serve as a test vehicle to demonstrate the effectiveness of new VE manufacturing techniques. The goal of the SBIR is to develop new, readily reconfigurable ways of manufacturing high power millimeter-wave VE devices that reduce the fabrication time by at least a factor of 10 compared with the state-of-the-art. Approaches that support the types of millimeter-wave interaction circuits that are compatible with high power (hundreds of watts), broadband (multi-GHz) devices are of particular interest including but not limited to structures such as folded waveguides, coupled cavities, and extended interaction cavities. At the beginning of Phase I, analyses and simulations with computational electromagnetic particle-in-cell and/or experimentally-validated large-signal codes shall demonstrate the ability of the proposed W-band amplifier design to meet the performance metrics of Table 1. During Phase I, interim experimental demonstrations of new fabrication and alignment techniques that support high precision and hermiticity goals are desirable (if feasible). By the end of Phase I, performers shall present (1) a full mechanical design of the W-band test amplifier (including piece-parts, sub-assemblies, and final assembly); (2) a detailed description of the manufacturing process flow that highlights the innovative approaches to achieving cycle time, yield, and cost goals; (3) a comparison with the VE manufacturing state-of-the-art; and (4) a Phase II roadmap that includes the fabrication and experimental demonstration of the W-band amplifier. Proposers interested in submitting a Direct to Phase II (DP2) proposal must provide documentation to substantiate that the scientific and technical merit and feasibility described above has been met and describe the potential applicability of the proposed manufacturing approach(es) to the small lot/discontinuous production scales that are typical of DoD VE procurements. Documentation should include all relevant information that may include but is not limited to: technical reports, published journal articles, prototype models and validation data, and examples of internally-developed processes. For detailed information on DP2 requirements and eligibility, please refer to the DoD BAA 2022.4 and DARPA BAA Instructions. Schedule/Milestones/Deliverables There will be a Kick-off Meeting at the onset of the program and periodic review meetings to be held by video-teleconferencing. Phase I milestones for this program should include: • Month 2: Analyses and computational simulations demonstrating that the W-band amplifier design is capable of meeting the performance goals outlined in Table 1 (including electron beam generation and transport, beam-wave interaction, and thermal management). • Month 4: Report on initial mechanical designs, assembly techniques, and manufacturing process flows related to the W-band amplifier. • Month 8: Interim reporting on mechanical designs, assembly techniques, and manufacturing process flows related to the W-band amplifier. Experimental demonstrations of new fabrication and/or alignment techniques, if applicable. • Month 10: Final Phase I Report that includes (1) a full mechanical design of the W-band test amplifier (including piece-parts, sub-assemblies, and final assembly); (2) a detailed description of the manufacturing process flow that highlights the innovative approaches to achieving cycle time, yield, and cost goals; (3) a comparison with the VE manufacturing state-of-the-art; and (4) a Phase II roadmap that includes the fabrication and experimental demonstration of the W-band amplifier. PHASE II: Phase II is an 18-month program to demonstrate the effectiveness of new mechanical designs, fabrication and alignment approaches, and process flows leading to a significant reduction in millimeter-wave VE device fabrication time (by at least a factor of 10 compared with the state-of-the-art), high manufacturing yield, and reduced costs. If appropriate, automation techniques may be developed and demonstrated in the Phase II Base program to support improved process flows. Using the technical approaches developed in Phase I, a minimum of one (1 each) W-band VE amplifier will be fabricated and tested. Throughout Phase II, as appropriate, measurements of piece-parts and sub-assemblies shall demonstrate their ability to achieve manufacturing tolerance, alignment, and hermiticity goals. Experimental measurements of the final sealed W-band amplifier shall demonstrate that the device meets the performance metrics of Table 1 and provide validation of new fabrication and assembly techniques. A 6-month Phase II Option will further the development of automated approaches to fabrication, alignment, characterization, and inspection that leverage techniques demonstrated in the Phase II Base program. Key goals of the Phase II Option are to develop a roadmap for production-scale implementation of these approaches and to explore ways these approaches can address small lot/discontinuous production challenges that are characteristic of many DoD VE system procurements. i. Schedule/Milestones/Deliverables There will be a Kick-off Meeting at the onset of the program and periodic review meetings to be held by video-teleconferencing. Phase II milestones for this program should include: • Month 3: Quarterly Program Review (QPR) and report summarizing initial fabrication progress, schedule, plan for full power testing of the W-band amplifier, and future work. • Month 6: QPR and report summarizing fabrication progress and planned work. As appropriate, present measurements of piece-parts and sub-assemblies demonstrating their ability to meet manufacturing tolerance, alignment, and hermiticity goals. • Month 9: QPR and report summarizing fabrication progress and planned work. As appropriate, present measurements of piece-parts and sub-assemblies demonstrating their ability to meet manufacturing tolerance, alignment, and hermiticity goals. Update on amplifier test procurement and experimental setup. • Month 12: QPR and report summarizing fabrication and assembly results, experimental validation, and comparisons with program metrics. Revised plans through the end of Phase II. • Month 15: QPR and report summarizing the fabrication and initial testing of the W-band amplifier, experimental validation, and planned work through the end of Phase II. • Month 18: End-of-Phase Review and report presenting descriptions of key innovations in design, fabrication, alignment, and assembly; experimental validation results; and comparisons with program metrics. Assessment of improvements over the VE manufacturing state-of-the-art. Proposed plan for a Phase II Option to develop automated approaches to fabrication, alignment, characterization, and inspection. The Phase II Option milestones should include: • Month 21: QPR and report summarizing the interim development of automated approaches to fabrication, alignment, characterization, and inspection. Experimental demonstrations, as appropriate. • Month 24: End-of-Option Review and report summarizing the final automated approaches to fabrication, alignment, characterization, and inspection. Assessment of improvements relative to the VE manufacturing state-of-the-art and recommendations for production-scale implementation, particularly in the context of small lot/discontinuous production challenges that are characteristic of many DoD VE system procurements. PHASE III DUAL USE APPLICATIONS: (U) Commercial and DoD/military applications for high power millimeter-wave VE amplifiers include compact transmitters for sensors, radar, and high-speed data links. The new design, fabrication, and alignment techniques developed by this SBIR will significantly reduce the cost and time of manufacturing and increase the overall manufacturing yields, facilitating the increased access to and adoption of the technology. In addition, the SBIR will develop new manufacturing process flows that leverage advances in automation and robotics to reduce the dependence on skilled touch-labor for the precision fabrication, assembly, and inspection of components and assemblies. REFERENCES: 1. T. J. Horn and D. Gamzina, “Additive manufacturing of copper and copper alloys,” ASM Handbook, Vol. 24, Additive Manufacturing Processes, D. Bourell, W. Frazier, H. Kuhn, and M. Seifi, eds., 2020. 2. Y. Koren, X. Gu, and W Guo, “Reconfigurable manufacturing systems: Principles, design, and future trends,” Front. Mech. Eng. 13(2) 2018. 3. A. Slocum, “Kinematic couplings: A review of design principles and applications,” Int. J. Mach. Tools Manuf. 50(4) 2010. KEYWORDS: Vacuum electronics; millimeter-wave; precision manufacturing; reconfigurable manufacturing
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