vacuum electron devices, namely, backward wave oscillators and traveling wave tubes; components of vacuum electron devices, namely, cathodes, electron guns, slow wave structures, electron collectors, magnets, magnetic circuits, and vacuum envelopes; millimeter wave electronic systems, consisting primarily of signal sources, amplifiers, detectors, modulators, demodulators, power supplies, phase shifters, and attenuators for wireless communications; and terahertz electronic systems, consisting primarily of signal sources, amplifiers, spectrometers, power supplies, mirrors, lenses, and detectors for use in detection of cancerous tissue, toxic solids, gases and liquids, concealed explosives and contraband, biomarkers, chemical/biological threats, and pathogens