Showing papers on "Beam (structure) published in 1970"

Transport: A Computer Program for Designing Charged Particle Beam Transport Systems

Abstract: TRANSPORT is a first- and second-order matrix multiplication computer program intended for the design of static-magnetic beam transport systems. It has been in existence in various evolutionary versions since 1963. The present version, described in the manual given, includes both first- and second-order fitting capabilities. TRANSPORT will step through the beam line, element by element, calculating the properties of the beam or other quantities, described below, where requested. Therefore one of the first elements is a specification of the phase space region occupied by the beam entering the system. Magnets and intervening spaces and other elements then follow in the sequence in which they occur in the beam line. Specifications of calculations to be done or of configurations other than normal are placed in the same sequence, at the point where their effect is to be made.

Relativistic Nonlinear Propagation of Laser Beams in Cold Overdense Plasmas

Abstract: The nonlinear propagation of a very intense laser beam in a cold overdense plasma is analytically investigated; the laser beam is assumed to be intense enough to cause the directed component of electron velocity to be comparable to the velocity of light. Special attention has been given to the case when coupled longitudinal‐cum‐transverse modes propagate in the plasma. An interesting result is that the beam can readily propagate through the overdense plasma, in contrast to what would be expected on the basis of a linear theory of laser propagation.

Propagation of High Current Relativistic Electron Beams

Abstract: Theoretical self‐consistent relativistic electron beam models are developed which allow the propagation of relativistic electron fluxes in excess of the Alfven–Lawson critical‐current limit for a fully neutralized beam. Development of a simple, fully relativistic, self‐consistent equilibrium is described which can carry arbitrarily large currents at or near complete electrostatic neutralization. A discussion of a model for magnetic neutralization is presented wherein it is shown that large numbers of electrons from a background plasma are counterstreaming slowly within the beam so that the net current density in the system, and therefore, the magnetic field, is nearly zero. A solution of an initial‐value problem for a beam–plasma system is given which indicates that magnetic neutralization can be expected to occur for plasma densities that are large compared with beam densities. It is found that the application of a strong axial magnetic field to a uniform beam allows propagation regardless of the magnitude of the beam current. Some comparisons are made with recent experimental data.

Beam-Foil Spectra of Boron 450–5000 Å*

Abstract: Electronic transitions in B by beam foil technique for spectral lines in 450-5000 A range, measuring excited levels mean lives

A Multiple Degree-of-Freedom Approach to Nonlinear Beam Vibrations

Abstract: The steady-state free and forced response and stability for large amplitude motion of a beam with clamped ends is investigated. Elastic restraint of the ends is included in order to relate theory with experiment. A multimode analytical and numerical technique is used to obtain theoretical solutions for both response and stability. Experimental results largely confirm the results of the analysis. It is concluded that, while single mode analyses are adequate in some cases, there are circumstances where a multimode analysis is essential to predict the observed results. Nomenclature Am = amplitude of the rath mode E = Young's modulus F = transverse force FQ = generalized force h = beam thickness I = second moment of area of the cross section Ks = axial spring factor k = axial spring constant ki = rotational spring constant L = beam length PO = initial axial tension Pom = nondimensional amplitude of the generalized harmonic force t = time w = transverse displacement x = axial coordinate Mmkin,Fim, = modal constants GmrsjGmgrs

Electro-optical image-tracing systems, particularly for use with laser beams

Abstract: To provide for digital positioning, without inertia of moving parts, a laser beam is transmitted to a substrate which is to be exposed, etched, or the like, particularly when microcircuits are to be produced, by monitoring the displacement of the substrate, mechanically, in two mutually perpendicular directions and positioning the laser beam, as monitored, in at least one direction by controlling voltages applied to a deflector cell in the path of the laser beam, by digitally, selectively, energizing an electro optical crystal effective to rotate the polarized laser beam through a plane of 90*, followed by a doubly refracting crystal which deviates the path of the laser beam, depending on its direction of polarization with respect to the optical axis of the crystal, so that, by successive deflections, the beam, from the laser, can be positioned in predetermined locations on the substrate The entire arrangement is preferably computer controlled, so that data inserted into the computer will cause deflection of the laser beam in accordance with a predetermined program

Zero-field quantum beats subsequent to beam--foil excitation.

Abstract: M sub L alignment creation due to beam foil excitation process demonstrated with zero field quantum beats in He and H emission spectra

Evanescent field coupling into a thin-film waveguide

Abstract: We have derived expressions for the field induced in a thin-film waveguide by plane waves incident upon an adjacent frustrated total reflecting interface. From these, we have deduced an expression for the coupling coefficient for a Gaussian TEM 00 beam into such a guide as a function of the guide and beam parameters.

Optical field flattening devices

Abstract: An optical device, for imposing a preselected degree of curvature upon an optical field associated with an image-bearing incident light beam, employs a light-polarizing beam splitter for splitting the incident light beam into a transmitted first beam and a reflected second beam, which first and second beams are linearly polarized in mutually perpendicular respective directions. Respective concave mirrors reflect the first and second beams so as to return them to the beam splitter, but respective polarization-changing members, mounted between the beam splitter and the concave mirrors, rotate the directions of linear polarization of the first and the second beams through 90* in the course of their passage from and back to the beam splitter. As a result, the returned first beam is reflected by the beam splitter, and the returned second beam is transmitted thereby for recombination with the first beam to form a single output beam.

Simultaneous multiple lead bonding

Abstract: The bonding of multiple leads on an individual basis is a tedious, time-consuming operation which is often impractical and uneconomical. For example, in bonding individual leads with a beam of radiant energy such as a laser beam, it is frequently impractical and uneconomical to align the lead with a bonding site, align the bonding site and the lead with the beam of radiant energy, apply the laser beam and then repeat the process for each lead to be bonded. As disclosed herein, a beam of radiant energy is shaped into a predetermined pattern so that the beam can be simultaneously applied to a plurality of leads. A composite cylindrical lens is disclosed, for example, which includes a plurality of cylindrical lens segments wherein a line formed by each segment when a collimated beam of radiant energy strikes the composite lens forms a side of a polygon. A perimeter pattern may be formed in this manner which is suitable for simultaneous multiple lead bonding. For example, in simultaneously bonding a plurality of leads extending from a beam leadlike device, the perimeter pattern may have essentially the same configuration as the device so that radiant energy may be applied simultaneously to the leads to be bonded without applying the radiant energy directly to the device itself.

Method of and apparatus for the separation of isotopes

Abstract: A method of and apparatus for the separation of an isotope from a working medium wherein a beam of atoms comprising the working medium may be generated in an oven and collimated with a suitable collimator. The collimated beam of atoms is directed through an evacuated region where two photon beams are applied to the beam and function respectively to excite and ionize a selected isotopic constituent of the atomic beam. The ionized isotope may then be removed from the atomic beam by electric or magnetic fields and collected on a collecting plate.

Excitation of the dominant mode of a round fiber by a Gaussian beam

Abstract: The excitation of the dominant HE 11 mode of a round optical fiber by a gaussian beam has been calculated. The calculation is based on the assumption that reflected waves can be neglected. It is thus applicable only to fibers with low index difference between core and cladding. It is found that optimum excitation of the HE 11 mode is achieved for loosely guided beams if the product of the beam half-width w times the radial decay constant γ of the HE 11 mode outside of the guide is unity, γw = 1. For tightly coupled modes 2½w must be equal to the core radius in order to achieve optimum excitation. As much as 99 percent of the power can be transferred to the HE 11 mode. Also investigated are the effects of an off-set or tilted beam on the mode excitation. The mode excitation drops to 36 percent if the amount of off-set equals the beam half-width. The effect of tilts depends on the parameter kd, free space propagation constant times core radius of the fiber. For small values of kd or loosely guided modes, the mode excitation is very sensitive to tilts of the gaussian beam. As long as the HE 11 mode is the only mode that can propagate, increasing values of kd lead to less sensitivity with respect to tilts. For multimode operation of the fiber, the sensitivity to tilts increases with increasing values of kd. The minimum of tilt sensitivity coincides with the minimum spot size of the guided mode.

Forward scatter optical turbidimeter apparatus

Abstract: An optical turbidimeter including a light source for generating a ribbon-shaped light beam for transmission through a fluid process stream, a first light detector for measuring the intensity of the light beam after passage through the process stream, a second light detector responsive to light scattered in the forward direction by the direct beam, spatial filtering optics for focusing the scattered light only from a center section of the direct beam onto the second detector and electronic signal processing means responsive to the signals generated by the two detectors for developing an output signal proportional to the ratio of the scattered light to the transmitted light beam.

Radiant energy beam scanning method and apparatus

Abstract: A radiant energy beam scanning method and apparatus having means for projecting a beam of radiant energy toward and bringing the beam to focus within a scanning plane, scanning means for deflecting the beam laterally to cause scanning motion of the beam along a prescribed scan track within the scanning plane, and servo means for sensing lateral departure of the beam from the scan track, generating tracking error signals related to the direction of such departure, and controlling the scanning means in response to the tracking signals to maintain the beam on the scan track. A recording and playback method and apparatus embodying the scanning apparatus for recording a data track on a record and subsequently playing back the data track.

Arc deposition apparatus

Abstract: A deposition process comprising emitting a beam of particles consisting of atoms and ions of source material, each particle having a kinetic energy between about 10 and 100 electron volts. The particles are deposited onto an object to coat the object with a thin film of source material. A beam gun is provided having an anode and a cathode and is supplied with current of such magnitude as to cause an arc discharge to occur between the anode and cathode to emit the beam.

Method of making printing masks with high energy beams

Abstract: A STENCIL MASK SUITABLE FOR PRINTING ELECTRONIC CIRCUITS AND THE LIKE IS MADE BY APPLYING A BEAM OF HIGH-ENERGY EMMISIONS SUCH AS AN ELECTRON BEAM OR A LASER BEAM TO AN ORIGINAL BLANK COMPRISING TWO LAYERS OF DIFFERENT VOLATILLZABILITY IN RESPONSE TO IMPRINGMENT BY THE BEAM. THE BEAM IS APPLIED TO THE LAYER WHICH IS MORE READILY VOLATILIZED TO FORM A GROOVE THERETHROUGH BOTTOMING AT THE INNER SURFACE OF THE SECOND LAYER. PERFORATIONS EXTENDING ENTIRELY THROUGH THE BLANK ARE PRODUCED WHERE DESIRED BY INCRESING THE BEAM ENERGY APPLIED TO SELECTED POINTS ALONG THE BOTTOM OF THE GROOVE. BECAUSE THE SECOND LAYER IS LESS READILY VOLATILIZED, UNCONTROLLED VARIATIONS IN THE DEPTHS OF THE GROOVES AND THE DANGER OF HAVING A GROOVE BREAK ENTIRELY THROUGH THE BLANK WHERE THIS IS NOT DESIRED ARE MINIMIZED.

ELECTRON MEAN FREE PATH NEAR 2 keV IN ALUMINUM

Abstract: : The mean free path for elastic scattering and for plasmon production was determined from beam attenuation measurements on films of various thicknesses. (Author)

Temperature Effects on High‐Frequency Beam Plasma Interaction

Abstract: The dispersion equation corresponding to the interaction of an electron beam with a Maxwellian plasma has been solved in quasistatic and infinite geometry approximations. Two representative beams are considered: a parallel beam with isotropic velocity spread and a helical beam with different longitudinal and transverse temperatures. The aim of the work is to predict the frequency, growth rate, and wavenumbers of the most unstable waves as functions of the basic beam and the plasma parameters. The results of the calculations are presented in graphs suitable for comparison with the experiments. The effect of plasma and beam temperatures on the spectrum of the instabilities is discussed in detail. It is shown that the plasma temperature reduces the growth rate of the instabilities at cyclotron harmonic frequencies while a velocity spread in the helical beam suppresses the instabilities everywhere, except in the vicinity of the cyclotron harmonics.

Young's and Shear Moduli of Unidirectional Composites by a Resonant Beam Method

Abstract: The resonant frequencies of unidirectional graphite epoxy com posite beams were found to deviate markedly from classical beam theory predictions at higher modes of vibration. Timoshenko beam theory was used to account quantitatively for the dependence of ex perimental resonant frequencies on mode of vibration, length/thickness ratio, and the ratio of Young's modulus/shear modulus of the com posite beam. By using reasonable values for the longitudinal-trans verse shear moduli, the longitudinal Young's modulus of anisotropic composite beams under vibration agreed well with values determined by static tests and became independent of mode of vibration and L/t. The vibrating beam test method was employed for the deter mination of E11, E22, and G12.

Acoustical Beam Patterns for Bats: Some Theoretical Considerations

Abstract: Acoustical beam patterns for emission from several different bats are calculated assuming a piston source in an infinite baffle, both as single and as double emitters. The calculated beam patterns agree well enough with experimental values available in the literature to justify the assumptions used. For those bats which possess no facial appendages to serve as a baffle, the simple acoustical model does not work, as anticipated. The calculated beam patterns are for fixed frequencies in the examples used; however, some aspects of frequency modulated beams are briefly discussed.

Beam Spread of Laser Light Propagating in a Random Medium

Abstract: We consider here the beam spread of laser light when it propagates in a random medium. The analysis is given in terms of the coherence function. Explicit results are obtained principally for the region of multiple scatter. In this region, it is shown that the irradiance pattern is always gaussian and that the characteristic beam diameter increases at a rate proportional to z32, where z is the propagation distance. The proportionality constant is determined for an arbitrary index-of-refraction spectrum, and the Kolmogorov spectrum is given as a special case. The results obtained are considered in atmospheric and oceanographic applications.

Effects of Absorption at 10.6 μ on Laser-Beam Transmission

Abstract: Theoretical evaluation of the effects of absorption of a laser beam at 10.6 μ has been investigated using the techniques of geometric optics. The interaction is nonlinear because the refractive index depends, through the mechanism of absorption, upon the irradiance distribution in the propagating wave. Atmospheric absorption at 10.6 μ is caused by CO2 and H2O in the atmosphere. Associated with absorption by CO2 and transverse flow caused by atmospheric winds or beam motion are vibrational relaxation effects, which can either heat or cool the atmosphere. If the atmosphere is cooled, the beam is self-focused. The velocity-altitude dependences of the heating and cooling regimes are defined. The amount of cooling increases with increasing altitude and decreasing relative humidity. Numerical results for the irradiance distribution in each regime are presented. At low altitudes the initially circular contours of the constant irradiance have been deformed into crescent-shaped contours and the beam has deflected into the wind. At high altitudes where significant cooling has occurred, the contours of constant irradiance are oval shaped with significant enhancement of the peak irradiance.

Anticorrelation in Two-Photon Attenuated Laser Beam

Abstract: The density matrix in the $P$ representation of a beam of radiation amplified by a two-photon amplifier has been derived up to the lowest order in the time-dependent perturbation theory without placing any restriction on the population of the state of the atom. It is shown that a laser beam containing noise in addition to the harmonic signal exhibits anticorrelation after being passed through such an amplifier, if less than one-sixth of the total number of atoms are maintained in the excited state.

Column approximation effects in high resolution electron microscopy using weak diffracted beams

Abstract: It is pointed out, and confirmed by calculation in a specific case, that the effects of the column approximation in calculating weak beam images of defects can be greatly reduced if the weak beams used make small angles with the Bragg planes.