TECHNOLOGY AREA(S): MaterialsOBJECTIVE: Develop novel compact and inexpensive plasma-based widely tunable frequency impedance elements (plasma switches) and antennas capable of sustained high-power operation in contested/denied electromagnetic (L- and S-bands) environments.DESCRIPTION: In the increasingly contested electromagnetic environment, Navy communication and guidance systems must have the capability to rapidly close the transmission “frequency window” when faced with electromagnetic threats, such as jamming or high-power microwave (HPM) weapons. Additionally, when faced with high-power electromagnetic threats, the communication and guidance systems should have the capability of being rapidly tuned to a different frequency outside the frequency range of the threat.While various technologies, including those based on semiconductors, ferrites, mechanical devices, etc., have been proposed to address these needs, the devices based on those technologies are bulky, have generally high insertion losses, and have either slow responses or are easily damaged when operating at high power levels.Devices based on low-temperature plasmas are promising for tunable high-power limiters and impedance elements. Plasma discharges can be turned on and their properties can be changed rapidly, on a nanosecond time scale. Insertion losses of such devices can be very low. Commercially available sealed plasma devices are also compact and inexpensive and have been shown to be robust in prolonged operation at Very High Frequency (VHF) to gigahertz (GHz) range frequencies; however, the characteristics of the gas mixtures are proprietary, and limited to a few commercially available sources with limited information on the plasma characteristics. The electromagnetic properties of plasma discharges are quite rich, combining resistive, inductive, and capacitive behavior, and those properties can be varied widely by, e.g., controlling the excitation waveform and power, applying a bias, and placing the plasma discharge in a resonant structure. Research aimed at understanding, characterizing, and evaluating such behavior is critical for the development of plasma-based limiters and switches, focused on improving performance and flexibility in a contested Radio Frequency (RF) environment.Based on previous research and development (References 1-3), the plasma-based switches and antennas should be frequency-tunable in a wide range (over an octave) and operate at a power level of over 100 Watts (W), but capabilities that have not yet been demonstrated. Radiation at this power level would enable multiple use-cases relevant to Navy operations.The Phase II effort will likely require secure access, and NAVSEA will process the DD254 to support the contractor for personnel and facility certification for secure access. The Phase I effort will not require access to classified information. If need be, data of the same level of complexity as secured data will be provided to support Phase I work.Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. owned and operated with no foreign influence as defined by DoD 5220.22-M, National Industrial Security Program Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Counterintelligence and Security Agency (DCSA). The selected contractor and/or subcontractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances, in order to perform on advanced phases of this project as set forth by DCSA and SSP in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material IAW DoD 5220.22-M during the advanced phases of this contract.PHASE I: Determine the technical feasibility of a concept by designing (a) an octave-tunable plasma switch capable of operation at 100 W, and (b) an octave-tunable antenna and/or antenna array that would effectively utilize such a switch. Begin characterization of radiation properties at this power level within the tunable frequency range.The Phase I Option, if exercised, will include the initial design specifications and identify risks and propose a plan to mitigate the risks in Phase II. Prepare a Phase II plan.PHASE II: Develop, characterize, and demonstrate a frequency-tunable plasma antenna and/or antenna array operating above 100 W and with a plasma switch that enables an octave frequency tuning at all power levels. Develop and validate a model to describe the plasma behavior in these devices. Develop optimal designs for both the switch and antenna using the model, given relevant use cases. Characterize the device lifetime under extreme thermal and shock conditions expected in applications. Prepare a Phase III development plan to transition the technology for Navy use and potential commercial use.It is probable that the work under this effort will be classified under Phase II (see Description section for details).PHASE III: Refine the designs developed in Phase II. Work with the Navy on integration of the devices into the application platforms and testing their performance in the relevant conditions. Based on the integration and testing, further refine the designs.The tunable high-power plasma switches and antennas are expected to be applicable for non-military applications such as cell phone towers.KEYWORDS: Rapidly Tuned Impedance Elements, Plasma, Plasma Discharges, Plasma-based Switch, Plasma-based Limiter, Antennas, Antenna ArraysReferences:1. Semnani, A., Peroulis, D. and Macheret, S. “Plasma-Enabled Tuning of a Resonant LC Circuit.” IEEE Transactions on Plasma Science, Vol. 44, No. 8, Part 2, 2016, pp. 1396-1404. https://ieeexplore.ieee.org/document/7516629
2. Semnani, A., Peroulis, D. and Macheret, S. “A High-Power Widely Tunable Limiter Utilizing an Evanescent-Mode Cavity Resonator Loaded With a Gas Discharge Tube.” IEEE Transactions on Plasma Science, Vol. 44, No. 12, 2016, pp. 3271 3280. https://ieeexplore.ieee.org/document/7756341
3. Semnani, A., Macheret, S. and Peroulis, D. “A Quasi-Absorptive Microwave Resonant Plasma Switch for High-Power Applications.” IEEE Transactions on Microwave Theory and Techniques, Vol. 44, No. 12, May 2018, pp. 1 9. doi: 10.1109/TMTT.2018.2834925
4. Khomenko A. and Macheret, S. “Capacitively coupled radio-frequency discharge in alpha-mode as a variable capacitor.” Journal of Physics D: Applied Physics, Vol. 52, No. 44. https://doi.org/10.1088/1361-6463/ab3367
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