Innovative Vacuum Electronics

Brief Program Description

    A collaboration has been formed between the six premier universities actively engaged in all aspects of multidisciplinary basic research and graduate instruction in innovative microwave vacuum electronics (MIT, Stanford, University of California, Davis, University of Maryland - College Park, University of Michigan, and University of Wisconsin). The goal is to answer the basic research issues required to maintain U.S. pre- eminence in this field of critical importance to the DoD through the 21st century and to train the required future leaders. The participating institutions possess unparalleled facilities ranging from state-of-the-art measurement and diagnostic instrumentation to complete prototype manufacturing and hot test capability. Strong emphasis is placed on collaboration with government laboratories including AFRL/Philhips Lab. JPL, NASA Glenn Lab., MIT Lincoln Lab. and NRL as well as will industries, such as CPI, Litton, Boeing, Teledyne, Northop Grumman . The program is administrated by Dr. Robert Barker of AFOSR and is coordinated with ARO and ONR.

    The consortium plans an intensive activity aimed at developing comprehensive, enhanced computational modeling capabilities and new algorithms addressing aspects of MVE devices spanning the spectrum from large signal interaction codes to advanced Green's function based simulation tools to augment particle-in-cell codes. Theoretical studies to be pursued include fundamental studies of noise mechanisms in MVE devices, development of basic theory and self-consistent simulation code for a photonic-band-gap- structure (PBG) aided gyroamplifier, and the investigation of mechanisms and control of electron beam halo and beam loss in MVE devices. Extensive analytic and numerical analyses are aimed at an understanding of the complicated physics of multitoned ultrawideband traveling wave tubes. Advanced signal processing methologies will be applied for predistortion equalization of UWB TWTAs. A custom-modified well diagnosed experimental test TWT permits the investigation of beam-wave interaction and the nonlinear time and space evolution of the carrier(s) and intermodulation products.

    Fundamental research will be conducted in novel electron emitters, ranging from oxide and active metal matrix thermionic cathodes to photo-enhanced field emitter arrays and ferroelectric arrays as well as plasma cathodes Significant emphasis will be placed on fundamental materials science issues, including the use of plasma deposition/ implantation for the metallization of high purity ceramics and millimeter wave sintering and tailoring of ceramics (lossy materials, windows, etc.) for MVE devices as well as plasma processing of high gradient surfaces. An intensive activity in novel solid state/MVE hybrid devices is expected to result in power output in excess of 100 W at 94 GHz and 140 GHz from small modules as well as high speed solid state controllers and novel beam steering techniques together with new linearization techniques. Fundamental studies of the effect of plasma introduction in MVE devices will be conducted. Novel light weight millimeter wave klystrinos will be investigated which employ advanced microfabrication techniques and which can be configured in arrays. The use of photonic bandgap based structures will be investigated for advanced source concepts. A wide range of fast wave amplifier concepts are under investigation at frequencies ranging from 15 GHz to 1 THz. Issues such as low operating magnetic field and voltage as well as compactness are particularly emphasized. An intensive, collaborative program of gyro-amplifier research will be conducted to demonstrate high efficiency, wide bandwidth devices in the Ka- and W-Bands, both in fundamental and harmonic operation. Several novel electron beam based frequency multiplication techniques are under investigation. Advanced solid state materials engineering and optical sensors permit new approaches ranging from TWT linearization to the control of "smart" tubes.

    Strong emphasis will be placed on innovative distance learning approaches which will facilitate the dissemination of MVE knowledge to the DoD and industry including both instructional materials and research findings. The increased bandwidth provided by Internet 2 will be extensively utilized to facilitate web based learning employing streaming video and real time video transmission of sessions using advanced numerical tools. On a longer timescale, it is envisioned that extensive use will be made of the wavelength division mutliplexed optical networks funded by DARPA. These provide the enormous bandwidth (10's of Gb/sec and eventually Tb/sec) required for the high speed data and image transmission and visualization required by the MVE program. A particularly serious issue is that of data archiving and mining and is consequently a subject of high priority for the MURI program. This will utilize a web based architecture to provide for microwave education, data archival, and the handling of large simulation codes.

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