Abstract: A device to provide high current, low emittance electron beams with a long life cathode. The device consists of an undulator 7 which provides a source of ultraviolet light 15 for an ultraviolet photocathode 8. The undulator 7 needs a supply of electrons to produce the ultraviolet light which it can get by diverting a portion of a beam from a linear accelerator 3 before E.sub.3 or after E.sub.4 the electron beam traverses a free electron laser 5. The device is self-maintaining once a source of electrons is developed but needs a start-up source of electrons. The start up source can be provided by a pulsed cathode electron gun 1 which has to be on for a short period of time until the ultraviolet photocathode 8 is operated.

Abstract: A semiconductor device comprises an inverted-tray-shaped support frame having a concave inner surface, a semiconductor element supported by the support frame at the center of its inner surface, and a plurality of leads which are formed on the inner surface of the support frame over an insulative layer interposed therebetween, and which extend from the center of the support frame outward to the periphery hereof and are electrically connected at their inner root ends to respective electrodes of the semiconductor element. The support frame reinforces and preserves the mechanical strength of the leads, which can therefore be spaced more closely and accurately.

Abstract: A semiconductor device for producing electro-magnetic radiation consisting of a radiation-emitting element (LED or laser) and an injection element, which can inject hot charge carriers into the active layer of the radiation-emitting element composed of layers of one conductivity type. With the use of active layers having a large band gap, for example GaN, short-wave light can be generated. According to the invention, the radiation-emitting element and the injection element constitute parts of the same epitaxial layer structure, the active layer being connected to the injection element by means of a semiconductor connection layer having a band gap larger than that of the active layer and that of the adjoining layer of the injection element.

Abstract: A high pressure self-sustained gas laser operating at a high specific energy loading and long pulselength. The laser comprises an endless duct for circulating a laser generating gaseous medium and two discharge electrodes for exciting the molecules of the gaseous medium. Behind the discharge cathode electrode is an electron-beam transmitter for transmitting a beam of preionizing electrons into the gaseous medium to preionize the region near the cathode discharge electrode. The region unpreionized by the electron beam is ionized by drifting electrons from the cathode region and avalanche ionization. The applied discharge voltage never exceeds the glow voltage allowing low discharge flush factors under repetitive operation with flowing laser gas.

Abstract: A laser arrangement includes electron beam apparatus comprising a plurality of electrodes, each of which having an aperture therethrough. The apertures are aligned along the longitudinal axis of an envelope which surrounds them and contains gas. The electrodes are electrically connected such that, of an adjacent pair, one is at a lower potential than the other. An electron beam is produced between the first electrode and an adjacent electrode, and is accelerated along the axis through the apertures, the electron current increasing in magnitude. The electron beam produced is used to provide pumping powder to the gas contained within the envelope such that it acts as a laser amplifying medium.

Abstract: A free electron laser (FEL) is disclosed in which the phase of the output electromagnetic beam is inherently adjustable without the use of any extraneous optical phase shifting materials. This is accomplished by implementing the FEL as a pair of series-connected wiggler cavity sections, and varying the relative phases of the bunched electron flow in the first cavity section relative to the second. In a preferred embodiment a series of electrodes are provided in a transition region between the two cavity sections, and variable voltages are applied to the electrodes to electrostatically control the electron transit time through the transition region, and the electron velocity upon exiting from that region. This translates into a control over phase and frequency.

Abstract: A free-electron laser capable of operation at a shorter wavelength than the fundamental lasing wavelength, but without any increase in electron energy requirements. The laser includes a conventional high-energy electron beam source and a wiggler transverse magnetic field through which the beam is passed to produce lasing. Opposed optical mirrors are selected to be reflective at a selected harmonic wavelength as well as at the fundamental wavelength. Lasing is initiated at the fundamental wavelength, but is then supported at the selected harmonic wavelength as well. By appropriate design lasing at the fundamental wavelength may be subsequently terminated without affecting lasing at the harmonic wavelength, which continues at a substantially reduced energy cost than would have been incurred if lasing at the harmonic frequency been initiated in a fundamental mode.

Abstract: The luminescent screen of a cathode ray tube includes an array of monocrystalline or amorphous phosphor rod-like elements which are covered with a reflective coating except for one end of each element which serves as an output face. The phenomenon of the light trapping is advantageously exploited to achieve enhanced brightness. The screen is illuminated with an electron beam which has an essentially oblong cross section and which is oriented along the elongated dimension of the elements. In one embodiment the elements comprise epitaxial Lu.sub.3 Al.sub.3 Ga.sub.2 O.sub.12 :Ce on the top of a YAG substrate, and a light absorbing layer of Lu.sub.3 Al.sub.3.5 Fe.sub.1.5 O.sub.12 is formed on the bottom of the substrate. A printer utilizing such a CRT is described. Also described is a configuration in which each of the rod-like elements functions as a laser.

Abstract: A lighting device is provided for emitting superradiant fluorescent light. First material layers are provided which emit predetermined electromagnetic waves of spontaneous emission when supplied with a predetermined energy (e.g. a pumping ray or beam). Second material layers, transparent to the electromagnetic wave, are stacked between the layers of the first material. To provide an improved light emission, the second material layers are arranged so that the interspaces l between the first material layers are smaller than c.multidot..tau..sub.R, where c is the velocity of said electromagnetic wave and .tau..sub.R is a time constant of the spontaneous emission.

Abstract: An electron gun for emitting a modulated electron beam. The gun includes an evacuated envelope having an output end with a photocathode positioned in the envelope and responsive to light to emit electrons. An anode is positioned between the photocathode and the output end for accelerating the electrons emitted by the photocathode. The gun further includes a source of potential interconnecting the anode and the photocathode for maintaining the anode electrostatically positive relative to the photocathode. A first laser provides a first laser beam at a first frequency illuminating the photocathode, and a second laser provides a second laser beam at a second frequency illuminating the photocathode at the same time. The first frequency differs from the second frequency by a beat frequency, whereby the photocathode provides the electron beam with the electrons spacially bunched in accordance with the beat frequency. A method of providing a modulated electron beam is also disclosed.

Abstract: An ion or electron beam is steered or focussed by a circular magnetic field produced by passing a large electrical current through a straight conducting wire, the magnetic field being co-axial with the wire. Annular beams of charged particles coaxial with the straight wire can be focussed onto a circular spot or, depending upon the entry radius of the annular beam and the magnetic field strength, can be induced to follow a looping trajectory. The effect of the steering or focussing system can be enhanced by the provision of a cylindrical conductor which is co-axial with the straight conducting wire and maintained at a voltage sufficient to produce the desired particle trajectory such that the particle beam passes between the wire and the cylindrical conductor. The beam steering or focussing systems is applicable to the fields of beam current density intensification, ion implantation, ion separation and free electron lasers.

Abstract: A highly efficient laser employs a glow discharge electron gun and includes a solid wall cathode that emits a beam of electrons resulting in a plasma that is a negative glow discharge having an electron distribution that has a larger number of high energy electrons than would be present in a Maxwellian distribution of the same electron density.

Abstract: A device for producing or amplifying coherent radiation includes a semiconductor device such as a laser. By means of electrons of high energy produced by a semiconductor cathode of the device, population inversion is obtained in an active layer of the laser structure. In this manner, laser action is obtained, which offers advantages, especially with II-VI materials which emit radiation of a wavelength shorter than the usual III-V materials, and which do not permit the desired population inversion to be obtained in the same manner as in III-V materials, by means of current injection across a pn junction. The semiconductor cathode and the laser structure can be arranged in mutual separation in a vacuum tube or be realized in one semiconductor body. The short-wave laser is especially advantageous for CD,DOR and VLP applications.

Abstract: A preferred embodiment of an excimer laser has a heat pipe oven adapted to raise sodium therein to a temperature of about 800 Kelvin and thereby vaporize the sodium at a pressure of no more than about 0.1 atmosphere, the heat pipe oven having substantially transparent ends. A ring cavity made up of a plurality of mirrors and an adjustable birefringent filter circulates violet light of a desired wavelength through the transparent ends of the heat pipe oven, and a pump laser introduces radiation into the heat pipe oven at an energy high enough to ionize sodium therein to form Na.sub.3.sup.+ ions and free electrons. The recombination of Na.sub.3.sup.+ ions and free electrons causes the ions to dissociate into free sodium atoms and excited Na.sub.2 molecules which, when stimulated by violet light of the desired wavelength, further dissociate into two free sodium atoms and emit additional violet light of the desired wavelength.

Abstract: The reduction of the grazing angle of electrons in an electron gun with a cathode emitting a beam of electrons which pass through a thin foil into a chamber is accomplished by geometrically tailored electron gun foil supports. One embodiment of the invention replaces the conventional rectangular shaped ribs with a set of triangular shaped ribs which produce a grazing angle A given by the equation ##EQU1## where T=the base width of the ribS=space between ribs at the baseH=height of the ribA=the angle the rib side makes with the incident electron which is perpendicular to the baseA=also the angle the electron scatters at from the rib surface.Another embodiment of the tailored foil supports entails the addition of triangular shaped caps to existing rectangular shaped ribs. The resultant reduction of the grazing angle of electrons improves the transmission efficiency of the electron gun and reduces the heat buildup on the supports and foil.

Abstract: Visible and ultraviolet lasers is based on excimer transitions in the diatomic homonuclear halogen molecules. Electron beam pumping of argon and hydrogen iodide gas mixtures produces a strong green emission in I.sub.2 centered at 505 nm and a full width of half maximum (FWHM) of the gain spectrum of approximately 15 nm. The transition for the green I.sub.2 band is bound-to-free, so a laser on this transition is continuously tunable. The result is a room temperature excimer laser that is potentially tunable over a region of 150 .ANG. in the blue-green.

Abstract: A method and apparatus for obtaining uniform, high-energy, large-volume electrical discharges in the lasing medium of a gas laser whereby a high-energy electron beam is used as an external ionization source to ionize substantially the entire volume of the lasing medium which is then readily pumped by means of an applied potential less than the breakdown voltage of the medium. The method and apparatus are particularly useful in CO.sub.2 laser systems.

Abstract: High-frequency acoustic waves generated in the cavity 14 of an E-beam laser are suppressed by placing wedges 20 in the cavity. Each wedge 20 runs in alignment with and adjacent to a foil-support rib 12 so that the foil 10 lies between the rib 12 and the wedge 20. The wedges 20 are configured to fill the electron-shadow regions cast by the support ribs 12 and to efficiently scatter the acoustic waves so that they propagate longitudinally in the cavity 14 and can be absorbed by acoustic mufflers located upstream and downstream of the laser gas flow 16.

Abstract: A high power, electrically excited laser is disclosed wherein a laser gas is caused to flow through an excitation region in which an electric discharge is established along a direction transverse to the direction of flow of the laser gas between an anode and a porous cathode disposed on opposite sides of the excitation region, and wherein an electron beam is introduced into the excitation region along a direction parallel to the direction of the discharge. A first quantity of an auxiliary gas (preferably helium) having a normal glow current density at least an order of magnitude less than that of the laser gas is introduced into the upstream end of the excitation region adjacent to the cathode and caused to flow across the cathode surface along a direction parallel to that of the laser gas. A second quantity of the auxiliary gas is "bled" through the porous cathode and gradually added to the auxiliary gas stream flowing across the cathode surface.

Abstract: Room temperature laser action is achieved in a cathode ray tube (CRT) in which the target includes a plurality of semiconductor layers: a thin, wide bandgap buffer layer; a thicker, narrow bandgap active layer; and a much thicker wide bandgap cavity-length-adjusting layer. The light beam direction is essentially parallel to the e-beam direction and hence is scannable.

Abstract: A method and apparatus for constructing a continuous wave (CW) free elect laser (FEL) system capable of providing tunable high power laser radiation at short wavelengths using low-energy recirculating DC electron beams. This method replaces the static periodic magnetic field used in conventional FEL systems with an equivalently intense and continuous electromagnetic pump field having spatial periodicity less than 1 cm. The pump field is generated by a low-energy recirculated DC electron beam interacting with a transverse static periodic magnetic field.

Abstract: A low energy electron beam magnetometer that utilizes near-monoenergetic electrons thereby reducing errors due to electron energy spread and electron nonuniform angular distribution. In a first embodiment of the invention (FIGS. 3 and 4) atoms in an atomic beam 30 of an inert gas are excited to a Rydberg state (lasers 32, 33 and 34) and then electrons of near zero energy are detached from the Rydberg atoms (gas chamber 35 ). The near zero energy electrons are then accelerated by an electric field V.sub.acc to form the electron beam 21. In a second embodiment of the invention (FIG. 5) a filament 42 emits electrons into an electrostatic analyzer 40 which selects electrons at a predetermined energy level within a very narrow range. These selected electrons make up the electron beam that is subjected to the magnetic field being measured.

Abstract: Electromagnetic radiation (10) is provided in a gas mixture (12) including helium in the X(1) state and nitrogen in the Y(1) state.

Abstract: The onset of electric discharge instability in rare-gas monofluoride lasers pumped by electron beam sustained electric discharges (e.g., KrF*) is delayed by employing a laser gas mixture (such as 0.95 Ar, 0.05 Kr, and 0.005 F.sub.2) which includes a small amount of a halogen compound (NF.sub.3) having a rate coefficient for electron dissociative attachment which is much larger than that for fluorine (such as 0.0005 NF.sub.3). The addition of nitrogen trifluoride to the gas mixture modifies the halogen kinetics in a manner to reduce the effect that consumption of the fluorine fuel has on the growth of secondary electrons, and therefore the occurrence of instability in the discharge. The rare-gas metastable quenching coefficient for the nitrogen trifluoride is sufficiently small (on the order of six times smaller than that of the fluorine) so that the small amount of nitrogen trifluoride utilized to stabilize the discharge exerts little or no influence on the other laser processes.

Abstract: The onset of electric discharge instability in electron beam enhanced electric discharge lasers employing halides, such as rare-gas monohalides (e.g., KrF*) and mercury vapor halide (e.g., HgBr*), is delayed by limiting the production of secondary electrons during laser pulse generation, to account for critical loss of halogen or halide fuel. Secondary electron production is controlled, in order to extend the pulse duration before the onset of discharge instability, by temporal tailoring of the primary electron concentration in the electric discharge region across the temporal expanse of possible laser action; the population of primary electrons can be temporally restrained by temporal decrease of the current density of the electron gun output, as a function, for instance, of gun driving voltage, or by temporal defocusing of the electron beam so as to provide reduced densities within the electric discharge region.

Abstract: An electron beam device having a vacuum chamber in which an electron beam generator generates a directed stream of electrons. An electron beam window comprising a foil which seals the vacuum chamber is in the path of the stream of electrons and permits passage of the stream of electrons into a working region exterior of the chamber and adjacent the electron beam window. An electrode is positioned closely adjacent the foil and a second electrode is spaced from the foil to form an elongated working or, in the case of a laser, a lasing region between them. The electrodes are maintained at a high electrical potential which, along with the electron beam, molecularly excites a gaseous working medium between the electrodes. The included angle of electrons passing through and scattered by the foil is limited and the electron beam confined to a desired region by an external shield or bezel overlying the foil.