Abstract:
This disclosure relates to a microwave amplifier (22) having an active X-Band microwave cavity (33) for use in electron paramagnetic resonance (EPR) measurements on large, lossy, irradiated, samples such as a human finger. The amplifier comprises an input section (31), a drift section (32) and an output section (33) which is the aforementioned active microwave cavity. An electron beam is used to input RF energy into the cavity. The input and output section have small helical couplers (34) for coupling RF energy onto and off of the electron beam. The RF wave is essentially "trapped" in the cavity because of the non-reciprocal nature of the electron beam medium and because the guide (i.e., drift section) at the input to the cavity has dimensions such that the frequency of the RF microwave energy is below the guides lower cut-off frequency. Also, a frequency "locking" effect occurs in the output cavity. The input frequency can be varied from 1-2% yet the output frequency does not change. The active microwave cavity has a cylindrically shaped window (41) located at the back-end of the cavity which extends inward towards the region of high RF fields inside the cavity. A large, lossy, irradiated sample such as a finger can be inserted into or behind this window and analyzed for radiation damage.
Abstract:
A transverse field interaction multi-beam amplifier device comprising a structure having, for example, a plurality of discrete cathodes cylindrically located in succession along a central axis of RF propagation. In registration with the cathodes are a respective number of annular collectors located within an outer cylinder which also acts as the structure housing. Intermediate the cathodes and collectors are two additional coaxial cylinders, one having a relatively smaller diameter than the other, with the smaller diameter cylinder including respective number of discrete grids, while the larger cylinder comprises a structure preferably having a rippled or undulating slow wave wall surface and a respective number of annular slots formed therein. The cathodes emit radial beams of electrons which pass through and are bunched by the grids and then accelerated by the slots to the collectors while interacting with and being modulated by an input RF beam propagating along the central axis of the coaxial structure between a first pair of cylinder walls including the grids and cathodes and inducing an output beam in a second pair of cylinder walls including the slots in the slow wave wall surface and the grids.
Abstract:
A device for generating and radiating pulses of radio frequency/microwave energy in response to pulses of laser light in which a metal layer is ohmically bonded to each side of a substrate of semiconductior material and an antenna bowtie pattern is ohmically bonded to the metal layers to form a feed structure for a Luneburg lens type antenna. There is at least one aperture available on the substrate of the semiconductor material for permitting laser light to reach the disk to produce photoconduction. The photoconductive switch is electrically connected to the storage device to facilitate fast discharge of the stored energy through the switch. The feed structure is mounted on a motorized support stand, which is connected to a center post by an arm that can rotate 360° in the azimuthal direction and ±90° in elevation. The feed structure is located on the outermost shell of the Luneburg lens, and is concave to conform to the focal radius of curvature of the outermost shell. The feed structure remains at a fixed radius from the center of the Luneburg lens as it rotates about the outermost shell. One embodiment uses a hemispherical Luneburg type lens to produce a highly directional beam by having the rays from the feed structure enter the Luneburg lens and reflect off of the ground plane. The other embodiment uses a spherical, or an almost spherical Luneburg type lens to produce a highly directional beam by having the radiation from the feed structure enter the Luneburg lens and speadout to emerge from the opposite diagonal point as a parallel beam. Both embodiments can rapidly scan 360° in the azimuthal direction and approximately ±90° in elevation.
Abstract:
A projectile with an Air Pressure Wave Generator, a battery, fuze, safe and arm system, detonator system, and ancillary circuitry. The Air Pressure Wave Generator contains a supersonic or subsonic nozzle, an ogive, and a secondary propellant chamber, which contains a conventional high explosive and is consistent with the “form-fit” of the weapon rifling system, and designed so as to produce the desired Air Pressure Wave impulse on the target. The projectile also has chemical agent(s) and marker(s) inside the secondary propellant chamber, and/or inside the Air Pressure Wave Generator section that is located intermediate between the nozzle and projectile housing. The types and amounts of chemical agent(s) and marker(s) are consistent with the Air Pressure Wave Generator design to entrap the chemical agent(s) and marker(s) in the core or central section of the APW packet. The properties and parameters of the chemical agent(s) and marker(s) are chosen to produce the desired target effects and minimize unwanted spillage.
Abstract:
A high-gain, dielectric loaded, slotted waveguide antenna having a photonic bandgap, a high-impedance electromagnetic structure, in contact with the waveguide surface containing longitudinal slots, and a tailored dielectric material structure in contact with the outer surface of the photonic bandgap structure. The tailored dielectric structure at the inner most surface has the same effective dielectric constant of the waveguide material and the photonic bandgap structure. The effective dielectric constant is then incrementally or continuously reduced to have a dielectric constant close to that of the free-space value at the outer surface further distance from the waveguide array. The tailoring of the effective dielectric constant is achieved by layering a given number of slabs of different dielectric constants with sequentially reduced values, or by varying the chemical composition of the material, or by varying the density of the material imbedded with high dielectric constant particles.
Abstract:
A photoconductive switch coupled to an energy storage device wherein the tch is comprised of photoconductive semiconductor material while the energy storage device comprises two discrete dielectric mediums. Each medium having a conductive electrode on the top and bottom surfaces to essentially form parallel capacitors wherein the parallel capacitors are separated by a predetermined gap distance. A photoconductive switch electrically connected to each medium such that the switches are located on the opposite sides of their respective mediums. The predetermined gap distance (between the electrodes) and the photoconductive switches (on opposite sides of the storage devices) provide suppression of surface flashover between very high voltage, charged electrodes. Such flashover suppression allowing for very high power pulse generation.
Abstract:
A high voltage sub-nanosecond pulser and radiator including a radial transsion line consisting of a dielectric member sandwiched between two patterned layers of metallization, one of which comprises a plurality of radiating elements. A photoconductive semiconductor gallium arsenide switch is embedded in the dielectric member which has a constant thickness. The other layer of metallization includes an apertured grid adjacent one surface of the switch for application of an energization pulse of laser light.
Abstract:
Microwave oscillators and amplifiers which utilize a superconducting slow-wave circuit. The slow circuit is made from materials which exhibit superconductivity at relatively high critical temperatures. The slow wave circuit is integral with the device's vacuum housing. Coolant exterior to the vacuum housing maintains the circuit in the superconducting state. The slow-wave circuit, which protrudes into the vacuum housing provides modulation of an electron beam which traverses the interior of the vacuum housing. Output power is ultimately extracted from the slow wave circuit.
Abstract:
A broadband transverse field interaction continuous beam amplifier device mprised of an elongated continuous cathode modulating grid structure, an elongated continuous demodulating grid-collector structure, first or input waveguide transmission line means including the modulating grid for propagating an input RF wave transversely to an electron beam traveling from the cathode-grid structure to the output-collector structure where the electrons are bunched or modulated by the process of transverse wave interaction, and second or output waveguide transmission line means including the demodulating grid for propagating an induced amplified RF output wave resulting from prebunched electrons traversing the demodulator grid. Both input and output transmission line means include slow wave structures which are implemented in the grid structures.
Abstract:
A printed circuit Traveling-Wave Tube (TWT) with a vacuum housing containing either a pair of identical meanderline slow-wave interaction circuits or a pair of multi-arm spiral slow-wave interaction circuits printed on two identical Photonic Band Gap crystal structures, and a gridded electron gun assembly. Printed on the two identical Photonic Band Gap crystal structures are electrical connections to connect the heater, cathode, grid and acceleration electrodes of the electron gun assembly to a power supply, RF input and output connectors surrounded by ground planes, a depressed collector, and a set of electrical connections to the depressed collector. Zig-zag metal spacers between the two identical Photonic Band Gap crystal structures are used to form the electron beam vacuum gap. Printed conducting metal strips on each side of the meanderline slow-wave interaction circuits are used for electrostatic focusing and to reduce beam edge effects of a sheet electron beam.