Abstract: A high-power coaxial cable is disclosed comprising an inner conductor, an outer conductor coaxially disposed about and spaced from the inner conductor, and insulating fittings disposed between the inner and outer conductors near opposite ends of the cable to maintain a desired spacing between the inner and outer conductors. The insulating fitting at one end of the cable has a plurality of longitudinal holes therethrough to reduce the dielectric constant and the impedance of the fitting. The fitting is formed in two like sections joined at right angles to one another along a substantially 45.degree. interface, thereby defining a short 90.degree. turn for the inner conductor near the end of the cable. The fitting sections are retained in position by a surrounding mounting block, the opposite ends of which respectively receive a conductive sleeve and an end of the outer coaxial conductor in press-fit relationship.

Abstract: We disclose and claim a process for fabricating wraparound solar cells wherein vertical slots are scribed in a semiconductor wafer to initially define the lateral dimensions of the cell. Thereafter, photolithographic masking, etching and diffusion steps are used to define the geometry of a p-n junction of the cell. Then, using lift-off photolithography and a multiple-element metal deposition process, the solar cell grid lines are formed on one surface of the cell and p- and n-type metal contacts are extended around to the opposite surface of the cell. In this manner, the dimensions of the cell can be made less than the diameter of the semiconductor wafer from which it is made.

Abstract: A bistable latch circuit is disclosed which can be electrically programmed to be stable in only one of its two states so that this same state is always set when power is applied to the circuit. The circuit can be electrically reprogrammed at will to select either of its stable states, and it draws no dc current during either the program mode or read mode. During the read mode, the potentials on the circuit nodes are such that long data retention times are achieved.

Abstract: A gaseous mixture containing elementary particles (atoms or molecules) of first and second isotopes is exposed to laser radiation at a predetermined frequency to excite elementary particles of the first isotope without substantially exciting elementary particles of the second isotope. An electric discharge is established in the gaseous mixture to produce preferential ionization of elementary particles of the first isotope. Electrophoresis in the discharge (either cataphoresis or the formation of a plasma sheath at the lateral extremity of the discharge) causes preferential migration of elementary particles of the first isotope to a first location and preferential migration of elementary particles of the second isotope to a second location. Portions of the gaseous mixture enriched in the first and second isotopes, respectively, are removed from the respective first and second locations.

Abstract: A dual-mode electron gun for a traveling-wave tube is disclosed which selectively generates an electron beam of two different cross-sectional areas. The electron gun includes radially inner and annular control grids as well as a shadow grid disposed between the cathode and the control grids along the electron beam path. The shadow grid is provided with a suppressor ring which precludes electron emission from an annular portion of the cathode immediately radially outwardly of the cathode region over which the inner control grid projects, thereby eliminating generation of a spurious beam portion radially outwardly from the desired smaller cross-section beam.

Abstract: A gaseous mixture containing elementary particles (atoms or molecules) of first and second isotopes is exposed to laser radiation at a predetermined frequency to excite elementary particles of the first isotope without substantially exciting elementary particles of the second isotope. An electric discharge is established in the gaseous mixture to produce preferential ionization of elementary particles of the first isotope. Electrophoresis in the discharge (either cataphoresis or the formation of a plasma sheath at the lateral extremity of the discharge) causes preferential migration of elementary particles of the first isotope to a first location and preferential migration of elementary particles of the second isotope to a second location. Portions of the gaseous mixture enriched in the first and second isotopes, respectively, are removed from the respective first and second locations.

Abstract: A waveguide gas laser is disclosed excited with bursts of a transverse rf electric field at a frequency ranging from about 30 MHz to about 3 GHz. The bursts have a duration ranging from about 0.1 .mu.sec. to about 10 .mu.sec. and a repetition rate ranging from about 500 Hz to about 100 kHz. This excitation is sufficiently rapid to produce gain switching in the laser gas, resulting in high peak power, short duration, single-line laser output pulses.

Abstract: A termination device for absorbing RF energy waves in the termination chamber of a traveling wave tube. The termination device is formed by modifying two wedge shaped termination devices of the prior art. Specifically, two well known single wedge termination devices are sliced in half to produce two wedges each one half the thickness of the prior art single wedge device. The two halves are positioned with their newly formed surface, formed by the slicing, in opposed facing contact. The new double wedge thus has the same thickness as the prior single wedge and is readily accommodated within the termination chamber. The double wedge termination device greatly reduces small signal gain variations across the operating frequency band of the traveling wave tube.

Abstract: A laser beam flow tube arrangement is disclosed in which the Ranque-Hilsch effect is advantageously utilized to reduce thermal blooming in a laser beam. The arrangement includes a tubular member through which the laser beam is propagated longitudinally and a vortical flow generator in gas flow communication with the interior of the tubular member. The flow generator produces vortical flow of a gas having low absorption properties at the wavelength of the laser beam and introduces the vortically flowing gas into the tubular member. The gas flows along a helical path within the tubular member with a tangential velocity selected to provide a negative temperature gradient between the wall and axis of the tubular member which is substantially equal in magnitude to the positive temperature gradient therebetween due to the thermal blooming.

Abstract: A multi-line NH.sub.3 laser is disclosed pumped by a multi-longitudinal mode and multi-transverse mode laser beam from a high-pressure CO.sub.2 laser operating on the R(30) 9.2 .mu.m transition. The resulting comb of pumping wavelengths simultaneously pumps several close-lying sR(5,K) transitions in ammonia from the symmetric ground state to the antisymmetric .nu..sub.2 =1 state, providing simultaneous lasing on a plurality of sP(7,K) transitions of different K-values. A plurality of sP(5,K) ammonia laser lines originating in the .nu..sub.2 =1 antisymmetric band and terminating in the depleted lower pump levels are also generated.

Abstract: A broadband group delay waveguide lens utilizing an array of half wave plates is disclosed. The lens is comprised of an array of uniformly spaced sections of waveguide having various lengths. The waveguide lengths are selected so as to provide an equal time delay to all rays from the focal point to the aperture plane of the lens. Since equal time delay does not ensure equality of phase at the aperture plane, half wave plates are inserted in the waveguide elements for adjusting the phase of each ray to obtain a constant phase plane over the aperture plane at the design frequency. The inner surface of the lens is spherical with the radius of the sphere equalling the focal length of the lens. The outer surface may be ellipsoidal having a semi-minor axis equal to the focal length and the semi-major axis is dependent upon the waveguide cross section dimensions and the design frequency. Such a lens has a low aperture phase error over a relatively large frequency range.

Abstract: Millimeter wave transmission lines are disclosed for propagating electromagnetic waves of a wavelength ranging from about 10 mm to about 0.4 mm. The transmission lines comprise a fiber of co-crystallized thallium bromo-iodide consisting of from about 40 mole percent to about 46 mole percent thallium bromide and from about 60 mole percent to about 54 mole percent thallium iodide. The fiber may be cladded with a dielectric material having a dielectric constant less than that of the fiber. A number of alternate fiber and cladding cross-sectional configurations are disclosed including circular, square, rectangular, and elliptical.

Abstract: Optical devices are disclosed which rely upon Stark-induced resonant, tunable, and saturable birefringence and dichroism to provide both digital and linear amplitude optical modulators, optical shutters, tunable optical filters, and optical cutoff limiters. A Stark cell is disposed along a light beam path between two crossed polarizers with its electric field direction at 45.degree. to the polarizer pass directions. The Stark cell contains a medium exhibiting a dichroic absorption resonance at a predetermined frequency as well as birefringence at frequencies slightly above and slightly below the frequency of the absorption resonance. By applying an appropriate control voltage between the Stark cell electrodes, an electric field is generated within the Stark cell to tune the absorption resonance to overlap the frequency of an input laser beam and thereby vary the transmission through the device from maximum near resonance to zero at frequencies far away from resonance.

Abstract: A dye laser is disclosed wherein a plastic disk containing laser dye is moved within a cylindrical race relative to a stationary pumping laser beam such that the pumping beam effectively scans the surface of the laser disk along a cycloidal path as the disk rolls along the race surface. The cycloidal illumination pattern on the disk enables a significantly increased amount of laser material to be exposed to the pumping beam.

Abstract: A simple and compact testing device is disclosed for enabling the boresight alignment of a laser designator to be quickly and readily checked. The device includes a tubular housing having a closed end and an open end adapted to be attached to the designator. A target disk and a converging meniscus lens provided with a reflective coating on its surface facing the target disk are snugly disposed within the housing adjacent to its closed and open ends, respectively, with a tubular spacer member interposed between and abutting the target disk and the lens. A portion of the laser light emitted from the designator is directed by the lens toward the target disk such that after a predetermined number of reflections from the target disk and the coating on the lens this laser light is focused to a small area on the target disk. The target disk emits visible light which travels back into the designator to provide an indication of the location of the spot of impingement of the laser light on the target disk.

Abstract: An electrically excited laser is disclosed wherein a laser gas is caused to flow along a gas flow channel and through an excitation region thereof in which an electric discharge is established between an anode and a cathode disposed substantially flush with respective opposing walls of the gas flow channel, and wherein an electron beam is introduced into the excitation region along a direction parallel to the discharge direction. A shield arrangement is provided immediately downstream from the laser excitation region to confine the discharge to the region directly between the anode and the cathode. The shield arrangement includes a plurality of planar electrically insulating rack members disposed across the gas flow channel in respective spaced planes parallel to both the direction of the discharge and the gas flow direction, and a plurality of planar shelf members carried by the rack members and oriented with their board surfaces transverse to the rack members.

Abstract: Helical slow-wave structure assemblies including a helical dielectric supporting member are disclosed along with methods for fabricating such assemblies. After the slow-wave structure helix is wound on a mandrel, a masking helix is coaxially wound about the slow-wave structure helix in the same sense as the slow-wave structure helix over the helical space between turns of the slow-wave structure helix and in overlapping relationship with portions of adjacent turns of the slow-wave structure helix. The supporting helix is formed by plasma spraying dielectric material into the helical space between turns of the masking helix. The dielectric material is ground to a predetermined radial dimension, and the mandrel and the masking helix are removed. By utilizing a masking helix of tapered width, a dielectric supporting helix of tapered width may be fabricated to provide a slow-wave structure assembly with a tapered phase velocity.

Abstract: Narrow-band optical filters are disclosed utilizing a birefringent crystal exhibiting a change in sign in birefringence at a predetermined wavelength and relying upon wave coupling between ordinary and extraordinary polarizations of light at or near the predetermined wavelength. The crystal is disposed along the light path between appropriately oriented polarizers, and a dc electric field is applied to the crystal either parallel or perpendicular to the light path. The dc electric field produces the aforementioned wave coupling for light at the center wavelength of the filter which normally is equal to the predetermined wavelength. The filter center wavelength may be displaced from the predetermined wavelength by employing a spatially periodic electric field.

Abstract: A beam of ammonia molecules including the isotopes N.sup.15 H.sub.3 and N.sup.14 H.sub.3 is generated wherein some of the molecules of each isotope reside in an asymmetric energy state and other of the molecules of each isotope reside in a symmetric energy state. The symmetric state molecules are removed from the beam in a first state selector to provide a beam containing substantially only asymmetric state molecules of each isotope. The latter beam is fed to a resonant microwave cavity where it interacts with microwaves of a frequency inducing asymmetric state to symmetric state transitions for molecules of one of the isotopes but not for molecules of the other isotope. Either the asymmetric state molecules or the symmetric state molecules are removed from the resultant beam in a second state selector to provide a beam containing substantially only molecules of the other energy state enriched in the isotope N.sup.15 H.sub.3.

Abstract: Electronically tunable optical filters are disclosed wherein a spatially varying dc electric field is applied to successive regions of a birefringent crystalline medium disposed between a pair of suitably oriented polarizers along the path of a light beam to be filtered. The dc electric field, which may be either parallel or perpendicular to the light path, electro-optically produces in the birefringent medium an effective oscillation of the optic axis of the medium about the pass direction of the input polarizer in a plane perpendicular to the light path as a function of distance along the light path with a predetermined spatial variation to achieve a desired filter transmission characteristic. The electric field is generated from programmable control voltages to provide a wide variety of filter passband or stopband characteristics.