Showing papers by "Varian Associates published in 1968"

Production of High-Energy Neutral Atoms by Scattering of Ions at Solid Surfaces and Its Relation to Sputtering

Abstract: Experiments performed with an rf-induced gas discharge demonstrate the existence of neutral atoms with sufficient energy to cause secondary emission of electrons. Evidence is presented that these energetic neutrals are produced by ion neutralization and reflection at the target electrode surface.

Improved photoemitters using GaAs and InGaAs

Abstract: A luminous sensitivity of 900 µA/lm in a GaAs-Cs-O photocathode, and a photothreshold of 1.16 eV in an InGaAs photocathode with Cs-O or Cs-H 2 O surface layers, are reported.

Microwave window having dielectric variations for tuning of resonances

Abstract: A high-power microwave window structure is disclosed. The window structure includes a hollow waveguide having a dielectric wave permeable gastight partition sealed thereacross to form the window assembly. The window structure is capable of being impedance matched to the waveguide structure to provide a relatively wide passband. In certain windows the passband can be as wide as the recommended bandwidth for the waveguide itself. Such window structures are plagued by ''''trapped'''' and ''''ghost'''' resonant modes which are excited into resonance by slight asymmetries in the window structure. At their resonant frequencies, these modes couple energy from the main propogating mode to produce an impedance mismatch and at high-power levels, overheating and failure of the window structure. Thus, operation at high-power levels is typically restricted to frequency ranges between a pair of such resonant modes. The frequency separation between the resonant modes is increased to provide broader band operation by selectively tuning the resonant frequencies of these modes by selectively varying the electrical path length through the window structure for one or more of these modes. For example, the window is made thicker near the periphery where one of the resonant modes has its most intense electric fields and made thinner near the center where another of the modes has its intense electric fields to tune one of the modes higher in frequency, while the other mode is being tuned lower in frequency. The mean thickness of the window is maintained approximately constant such as not to change appreciably the passband for the main propagating mode. Alternatively, the dielectric constant for various portions of the window can be changed for changing the electrical path length through the window as aforedescribed.

Nonelectron emissive electrode structure utilizing ion-plated nonemissive coatings

Abstract: A nonemissive electrode structure is disclosed together with a method for fabricating same. The nonelectron emissive electrode structure includes a core member which may be made of any one of a number of different metals such as molybdenum, copper, tantalum or tungsten. A nonelectron emissive material is deposited over the core metal. The nonemissive deposited layer may be any one of a number of different materials which will provide electron emission inhibiting characteristics in the presence of surface contamination by barium and/or strontium. Examples of such electron emission inhibiting materials include titanium, chromium, zirconium, or silicon. An outer coating of carbon is formed over the emission inhibiting layer to further enhance the nonelectron emissive characteristics of the electrode. Alternatively, the nonemissive deposited layer and carbon coating may be codeposited into a single covering layer deposited over the core material. The electrode structure is especially suitable as a grid structure in an electron discharge device employing either an oxide coated cathode or a dispenser cathode of the type containing barium and/or strontium.

R.f.sputter plating method and apparatus employing control of ion and electron bombardment of the plating

Abstract: AN R.F. SPUTTER PLATING METHOD AND APPARATUS IS DISCLOSED. THE PLATING APPARATUS INCLUDES A PARTIALLY EVACUATED DEPOSITION CHAMBER CONTAINING A PAIR OF ELECTRODES EXCITED WITH RADIO FREQUENCY ENERGY TO PRODUCE A RADIO FREQUENCY PLASMA DISCHARGE IN THE REGION THEREBETWEEN. THE R.F. DISCHARGE DEFINING ELECTRODES ARE OPERATED AT A FLOATING POTENTIAL SUCH THAT, BY THE NATURE OF THE PLASMA DISCHARGE, RELATIVELY HIGH NEGATIVE SELF-BIAS POTENTIAL IS ESTABLISHED ON THE R.F. ELECTRODES. A TARGET MATERIAL IS PLACED ON THE R.F. ELECTRODES TO BE SPUTTERED BY ION BOMBARDMENT, SUCH IONS EMANATING FROM THE PLASMA DISCHARGE. A COLLECTOR ELECTRODE IS DISPOSED TO RECEIVE THE SPUTTERED TARGET MATERIAL TO PLATE THE COLLECTOR ELECTRODE OR ITEMS CARRIED THEREON. A PAIR OF TRANSPARENT GRID STRUCTURES ARE DISPOSED INTERMEDIATE THE COLLECTOR ELECTRODE AND THE PLASMA DISCHARGE REGION. A FIRST ONE OF THE GRID STRUCTURES, ADJACENT THE PLASMA DISCHARGE, IS OPERATED AT GROUND POTENTIAL TO PREVENT PERTURBATION OF THE DISCHARGE, WHEREAS THE SECOND GRID STRUCTURE DISPOSED INTERMEDIATE THE FIRST GRID STRUCTURE AND THE COLLECTOR STRUCTURE IS OPERATED AT A POTENTIAL POSITIVE WITH RESPECT TO THE DISCHARGE FOR REPELLING POSITIVE IONS. THE COLLECTOR STRUCTURE IS OPERATED AT A POTENTIAL NEGATIVE WITH RESPECT TO THE SELF-BIAS POTENTIAL ON THE TARGET ELECTRODES TO REPEL ELECTRONS EMANATING FROM THE DISCHARGE REGION, WHEREBY ION AND ELECTRON BOMBARDMENT OF THE ITEMS BEING PLATED IS CONTROLLED.

Photoemitter having a p-type semiconductive substrate overlaid with cesium and n-type cesium oxide layers

Abstract: A junction-type photoemitter is disclosed. The photoemitter includes a heavily doped P-type semiconductive substrate for absorbing photons of radiation to be converted into electrons to be emitted. An alkali metal layer such as cesium metal is formed over the substrate member for filling the surface energy states of the P-semiconductive substrate. Finally, a layer of cesium oxide is formed over the alkali metal layer to provide a low-work function surface facing the vacuum into which the electrons are emitted from the photoemitter. The substrate member may be made of a III-V compound semiconductor or an alloy of two different III-V compound semiconductors (each compound semiconductor including one element from the third group of Periodic Table and another element of the fifth group of the Periodic Table) to provide a semiconductive band-gap energy which is equal to or slightly more than the work function of the cesium oxide layer. The P-type semiconductive substrate member is heavily doped with a concentration of acceptor dopant greater than 3 X 1018 acceptors per cubic centimeter. Likewise, the cesium oxide layer is heavily doped with donor atoms of cesium to provide the relatively low-work function characteristic of such material. In a preferred embodiment, the P-semiconductive substrate is formed of InP or an alloy of InP and InAs. The photoemitter has improved conversion efficiency in the wavelength range from 0.5 microns to 1.37 microns wavelength.

Superconducting magnet for persistent operation

Abstract: AN APPARATUS FOR PROVIDING A SUPERCONDUCTIVE MAGNET OF NIOBIUM-TIN RIBBON FOR PERSISTENT OPERATION AND INCLUDING AS NOVEL MEANS FOR ALLOWING THE COIL WINDING ENDS TO BE EXTRACTED FROM THE WINDING BOBBIN WITHOUT KINKING, A NOVEL MEANS OF SPLICING THE ENDS OF THE SUPERCONDUCTIVE RIBBON TO A PERSISTENT SWITCH MEANS, AND A MEANS FOR SUPPORTING THE SPLICED RIBBON OUTSIDE OF THE INTENSE MAGNETIC FIELD PRODUCED BY THE SOLENOID.

Method for growing tin-doped n-type epitaxial gallium arsenide from the liquid state

Abstract: A charge consisting of gallium, gallium arsenide, and tin was heated to produce a liquid molten solution of gallium, arsenic, and tin with the atom fraction of tin being below 80 percent in the solution. The charge and a gallium arsenide substance are preferably heated in a refractory boat contained within a hydrogen furnace tube, such boat being tilted at an angle such that the substrate wafer is above the liquid level of the solution. The boat is then tipped to cover the heated surface of the gallium arsenide substrate member with the liquified charge solution. The furnace is then allowed to cool, resulting in an epitaxial growth of tin-doped n-type gallium arsenide upon the gallium arsenide substrate member. Growth of the epitaxial layer occurs within a few minutes, after which the excess charge is scraped from the layer and the substrate member and is then treated with a solution of molten tin bromide to facilitate removal of the excess tin and gallium. The tin bromide and excess tin and gallium are removed from the epitaxial surface by treatment with hydrochloric acid. By varying the atom fraction of tin in the liquified solution, the net donor carrier concentration in the resultant epitaxial layer can be readily varied within the range from 1016 to 1018 per cubic centimeter.

Electron impact time of flight spectrometer

Abstract: An electron impact time of flight spectrometer including means providing monochromatic electrons of a predetermined kinetic energy which are caused to impinge upon a sample material so that some of the electrons experience an energy transition in passing through the material. The electrons are then differentially accelerated such that electrons having similar energy levels will be caused to converge and arrive at a detector in tightly formed bunches.

Gang tuner for a multicavity microwave tube

Abstract: A multicavity microwave amplifier tube is disclosed. The tube includes a plurality of cavity resonators successively arranged along a beam path for successive electromagnetic interaction with the beam to produce output-amplified microwave energy. Translatable cavity tuners are provided within a plurality of the cavity resonators for tuning the frequency of the resonators. The external tuning structure includes a plurality of rotatable cam wheels mechanically interconnected for synchronous rotation. Each cam wheel includes a set of cams. A plurality of cam followers are connected to the cavity tuners and each includes a bearing surface for engaging one of the cams in one the set of cams for tuning the respective cavity resonators in accordance with the position of the respective cam in the set of cams on the cam wheel. Means are provided for disengaging the cam followers from the cams before rotation of the cam wheels to new tuner positions. A stop is provided for the preventing rotation of the cam wheels while the cam followers are in engagement with the cams to alleviate wear on the engaging surfaces of the cams and the cam followers, whereby the microwave amplifier tube can be precisely and repeatedly tuned to certain preselected channel frequencies within a band of frequencies.

Retarding field electron diffraction spectrometer having improved resolution

Abstract: A retarded field electron diffraction spectrometer is disclosed which includes an electron gun for directing substantially monoenergetic electrons onto the surface to be examined of a target to produce scattered electrons from such surface. A spherical retarding grid structure is concentrically disposed of the target in the space between the target electrode and a concentric spherical fluorescent screen. A retarding potential applied to the retarding grid permits only those target scattered electrons having a potential greater than the potential of the retarding electrode to reach the fluorescent screen. The retarding grid electrode has grid openings defining electron passageways having a characteristic diameter less than three times the characteristic length thereof to improve the uniformity of the retarding field. A spherical shield grid electrode is concentrically disposed of and has a radius within the range of 0.3 to 0.8 of that of the retarding grid to enhance the resolution of the spectrometer.

O-ring with integral stem sealing means and butterfly valve using same

Abstract: 1,242,637. Valves. VARIAN ASSOCIATES. 3 Feb., 1969 [19 Feb., 1968], No. 5759/69. Heading F2V. In a butterfly valve 1, proper sealing in all states of the valve between the valve shaft 5, valve member 7 and valve housing bore 3, is achieved by locating a one-piece sealing ring 13 within a peripheral groove 11 formed in valve member 7, the ring having integral radially inwardly directed sleeve portions 16 which are located in appropriate recesses 12 formed in the valve member and serve to embrace the shaft 5, and furthermore, having annular portions 14 which serve to ensure sealing between the shaft and the shaft bores 4 and 4 1 . An adjustable movement-limiting screw 24 is provided on one of the faces of the valve member.

Charged particle trapping means employing a voltage divider and a plurality of simple conductors to produce complex trapping fields

Abstract: 1293148 Particle spectrometers VARIAN ASSOCIATES 17 Oct 1969 [21 Oct 1968] 51147/69 Heading H1D Apparatus for generating an electric field for trapping charged particles comprises a number of electrically isolated conducting elements, 1, 2 ... 7 for example, arranged to surround the space in which the field is to be generated and a voltage distribution arrangement which, when supplied with A.C. and D.C. voltages, provides appropriate voltages on the elements 1, 2 ... 7 to form the field, the lines of force of which extend through the space to end on respective conducting elements. Each conducting element defines in operation an equipotential line in a surface formed by the boundary of the space and the conducting elements are so arranged that this surface is not one for which the Laplace equation is satisfied for the desired trapping field. The equipotential lines of the field symmetrically intersect a plane to which an axis of symmetry of the space is perpendicular. As shown in Fig. 2, the elements 1, 2 ... 7 are straight, parallel, equispaced wires, forming a square in cross-section, which, when connected through linear voltage divider 12 to A.C.-D.C. source 10, produces the two-dimensional hyperbolic field distribution shown dashed and which may be used as a conventional quadrupole type mass filter. Adjustable capacitors 14 may also be provided to ensure proper division of the A.C. component. The voltages supplied to each element of each of a plurality of symmetrically disposed elements may be in phase and of equal amplitude. In Fig. 3 (not shown) the wires form a circle in transverse cross-section and a hyperbolic field may be formed either (a) with equally spaced wires and a non-linear voltage division or (b) with non-uniform wire spacing and a linear voltage division. A threedimensional trap is shown in Fig. 5 which has a set of circular equally spaced conducting rings 34 which are contiguous to a pair of facing right circular cones and connected to a linear potential divider, as in Fig. 2, to give equipotentials which are hyperboloids of revolution. Fig. 4 shows an arrangement similar to Fig. 5 in which the wires are replaced by concentric wires 36 which terminate to form the enclosed conical region. In a further embodiment, Figs. 6 and 7 (not shown), the rings or cylinders are made contiguous to a pair of facing right elliptical cones.