Laser beam assists in precision welding
Laser beam aiming method eliminates trial-and-error beam alinement in electron-beam welding.
Tolmei, V. R.↗
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Results for “BEAMS”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Laser beam color separator
Multiwavelength laser beam is separated into series of parallel color beams using prism and retroreflector. Setup is inexpensive and needs no critical adjustments. It can incorporate several prisms to increase dispersion and reduce overall size. Transmission grating can be used instead of prism with sacrifice in efficiency. Spatial filter can remove unwanted beams.
Franke, J. M.↗
RF beam center location method and apparatus for power transmission system
The receiving element in wireless power transmission systems intercepts the greatest possible portion of the transmitted energy beam. Summing the output energy of all receivers in a planar array makes it possible to determine the location of the center of energy of the incident beam on a receiving array of antenna elements so that the incident beam is in the microwave region.
Dickinson, R. M.↗
A simple element for multilayer beams in NASTRAN thermal stress analysis
In the application of NASTRAN, structural members are usually represented by bar elements with multipoint constraint cards to enforce the interface conditions. While this is a very powerful method in principle, it was found that in practice the process for specification of constraints became tedious and error prone, unless the geometry was simple and the number of grid points low. An alternative approach was found within the framework of the NASTRAN program. This approach made use of the idea that a thermal distortion in a multilayer beam may be similar to a homogeneous beam with a thermal gradient across the cross section. The exact mathematical derivation for the equivalent beam, and all the necessary formulae for the equivalent parameters in NASTRAN analysis are presented. Some numerical examples illustrate the simplicity and ease of this approach for finite element analysis.
Chen, W. T.↗
Observation of beam-generated VLF hiss in a large laboratory plasma
The paper describes a lab experiment on a beam-plasma instability under conditions for which the theory of VLF hiss is applicable. An energetic electron beam is injected into a cold, dense, almost collisionless magnetoplasma. Beam and plasma dimensions are so large that oblique whistler wave propagation and growth are readily observable. The observations of frequency and wave number spectra, growth rate, and instability level are consistent with theory and satellite observation in regions of electron precipitation.
Stenzel, R. L.↗
Experiments on current-driven three-dimensional ion sound turbulence. I - Return-current limited electron beam injection. II - Wave dynamics
Pulsed electron beam injection into a weakly collisional magnetized background plasma is investigated experimentally; properties of the electron beam and background plasma, as well as the low-frequency instabilities and wave dynamics, are discussed. The current of the injected beam closes via a field-aligned return current of background electrons. Through study of the frequency and wavenumber distribution, together with the electron distribution function, the low-frequency instabilities associated with the pulsed injection are identified as ion acoustic waves driven unstable by the return current. The frequency cut-off of the instabilities predicted from renormalized plasma turbulence theory, has been verified experimentally.
Stenzel, R. L.↗
Nonlinear flap-lag-axial equations of a rotating beam with arbitrary precone angle
In an attempt both to unify and extend the analytical basis of several aspects of the dynamic behavior of flexible rotating beams, the second-degree nonlinear equations of motion for the coupled flapwise bending, lagwise bending, and axial extension of an untwisted, torsionally rigid, nonuniform, rotating beam having an arbitrary angle of precone with the plane perpendicular to the axis of rotation are derived using Hamilton's principle. The derivation of the equations is based on the geometric nonlinear theory of elasticity and the resulting equations are consistent with the assumption that the strains are negligible compared to unity. No restrictions are imposed on the relative displacements or angular rotations of the cross sections of the beam other than those implied by the assumption of small strains. Illustrative numerical results, obtained by using an integrating matrix as the basis for the method of solution, are presented both for the purpose of validating the present method of solution and indicating the range of applicability of the equations of motion and the method of solution.
Kvaternik, R. G.↗
Continuum models for beam-like and plate-like lattice structures
A simple, rational approach is presented for developing continuum models for large repetitive beam-like and plate-like lattices with arbitrary configurations subjected to static, thermal and dynamic loadings. The continuum models for these structures are shear flexible beams and plates. They account for local effects in the repeating element of the actual structure and are characterized by their thermoelastic strain and kinetic energies from which the equations of motion and constitutive relations can be derived. The procedure for developing the expressions for thermoelastic strain and kinetic energies of the continuum involves introducing basic assumptions regarding the variation of the temperature, displacement and strain components in one or two directions (for plate-like and beam-like lattices) and obtaining effective thermoelastic and dynamic coefficients of the continuum in terms of material properties and geometry of the original lattice structure. The high accuracy of the continuum models developed is demonstrated by means of numerical examples.
Noor, A. K.↗
Development of a beam builder for automatic fabrication of large composite space structures
The composite material beam builder which will produce triangular beams from pre-consolidated graphite/glass/thermoplastic composite material through automated mechanical processes is presented, side member storage, feed and positioning, ultrasonic welding, and beam cutoff are formed. Each process lends itself to modular subsystem development. Initial development is concentrated on the key processes for roll forming and ultrasonic welding composite thermoplastic materials. The construction and test of an experimental roll forming machine and ultrasonic welding process control techniques are described.
Bodle, J. G.↗
Latitudinal beaming of Jupiter's low frequency radio emissions
By comparing RAE-1 and IMP-6 satellite measurements of Jupiter's radio emission near 1MHz with recent Voyager-1 and 2 observations in the same frequency range, the properties of the low frequency radiation pattern over a 10 deg range of latitudes with respect to the Jovian rotation equator can be studied. These observations, which cover a wider latitudinal range than is possible from the earth, are consistent with many aspects of earlier ground-based measurements used to infer a sharp beaming pattern for the decameter wavelength emissions. Marked, systematic changes are found in the statistical occurrence probability distributions with system 3 central meridian longitude as the jovigraphic latitude of the observer changes over this range. Simultaneous observations by the two Voyager spacecraft suggest that the instantaneous beam width may be no more than a few degrees at times. The new hectometer-wave results can be interpreted in terms of a narrow, curved sheet at a fixed magnetic latitude into which the emission is beamed to escape the planet.
Alexander, J. K.↗
Mapping of electrical potential distribution with charged particle beams
Potentials were measured using a beam of soft X-rays in air at 2 x 10 to the -5 power Torr. Ions were detected by a continuous-dynode electron multiplier after they passed through a retarding field. Ultimate resolution depends upon the diameter of the X-ray beam which was 3 mm. When the fields in the region of interest were such to disperse the ions, only a small fraction were detected and the method of measurement was not very reliable. Yet reasonable data could be collected if the ions traveled in parallel paths toward the detector. Development should concentrate on increasing the aperture of the detector from the pinhole which was used to something measured in centimeters. Also increasing the strength of the source would provide a stronger signal and more reliable data. Measurements were made at an estimated ion current to 10 to the -15 power A from a 10 cm length of the X-ray beam, this current being several orders of magnitude below what would have a perturbing effect on the region to be measured. Consequently, the source strength can be increased and prospects for this method of measurement are good.
Robinson, J. W.↗
Possibilities and limitations of rod-beam theories
Rod-beam theories are founded on hypotheses such as Bernouilli's suggesting flat cross-sections under deformation. These assumptions, which make rod-beam theories possible, also limit the accuracy of their analysis. It is shown that from a certain order upward terms of geometrically nonlinear deformations contradict the rod-beam hypotheses. Consistent application of differential geometry calculus also reveals differences from existing rod theories of higher order. These differences are explained by simple examples.
Peterson, D.↗
The nonlinear behavior of elastic slender straight beams undergoing small strains and moderate rotations
The nonlinear behavior of slender and initially straight beams is investigated. A set of equilibrium equations for a beam undergoing moderate rotations and small strains is derived. The derivation includes several assumptions which are clearly stated and explained. These equations are used to investigate the deformations of a cantilevered beam which is loaded by a concentrated transverse load at the free end. The numerical results are in very good agreement with the experimental results.
Rosen, A.↗
Temperature characteristics of electron beams and ambient particles
The temperature characteristics of electron beams and trapped particles of large pitch angles during substorms have been studied by examining the plasma data of the University of California at San Diego experiment on board the geostationary ATS 6 satellite. Approximating the observed distribution functions by a single Maxwellian or a superposition of two Maxwellians, it has been deduced that the electron distribution function is characterized by two temperatures, approximately 1 and 3 keV. The 3-keV component is observed at all pitch angles from 10 to 90 deg. The 1-keV component initially appears only within the electron beams which are confined to small pitch angles (approximately 30 deg). With time, this low-temperature component appears at larger pitch angles (approximately 30 deg). This observation has been interpreted in terms of scattering of the electron beams to large pitch angles.
Lin, C. S.↗
Latitudinal beaming of Jupiter's low frequency radio emissions
Observations of Jupiter's radio emissions from Jovigraphic latitudes greater than 3.3 deg are reported. The measurements were obtained from the Voyager 2 spacecraft at declinations up to 6.5 deg, and when these results are compared with simultaneous observations from Voyager 1 near the ecliptic plane (at a Jovigraphic latitude of about 3 deg), they indicate that the latitudinal-beaming effects persist and may even become stronger with higher latitudes. The results were combined with earlier low-frequency measurements from periods with De as low as -3 deg in order to show the beaming effects the occurrence of the emission over a full 10 deg range of altitude. The results of observations at frequencies near 1 MHz are also discussed, which were obtained from Voyager 1 and 2 in 1978, Rae 1 in 1969, and Imp 6 in 1971-1972. The implications of the new results for models of Jupiter's radio-emission beam pattern are considered.
Alexander, J. K.↗
Homogeneous alignment of nematic liquid crystals by ion beam etched surfaces
A wide range of ion beam etch parameters capable of producing uniform homogeneous alignment of nematic liquid crystals on SiO2 films are discussed. The alignment surfaces were generated by obliquely incident (angles of 5 to 25 deg) argon ions with energies in the range of 0.5 to 2.0 KeV, ion current densities of 0.1 to 0.6 mA sq cm and etch times of 1 to 9 min. A smaller range of ion beam parameters (2.0 KeV, 0.2 mA sq cm, 5 to 10 deg and 1 to 5 min.) were also investigated with ZrO2 films and found suitable for homogeneous alignment. Extinction ratios were very high (1000), twist angles were small ( or = 3 deg) and tilt-bias angles very small ( or = 1 deg). Preliminary scanning electron microscopy results indicate a parallel oriented surface structure on the ion beam etched surfaces which may determine alignment.
Wintucky, E. G.↗
Alternative Beam Efficiency Calculations for a Large-aperture Multiple-frequency Microwave Radiometer (LAMMR)
The fundamental definition of beam efficiency, given in terms of a far field radiation pattern, was used to develop alternative definitions which improve accuracy, reduce the amount of calculation required, and isolate the separate factors composing beam efficiency. Well-known definitions of aperture efficiency were introduced successively to simplify the denominator of the fundamental definition. The superposition of complex vector spillover and backscattered fields was examined, and beam efficiency analysis in terms of power patterns was carried out. An extension from single to dual reflector geometries was included. It is noted that the alternative definitions are advantageous in the mathematical simulation of a radiometer system, and are not intended for the measurements discipline where fields have merged and therefore lost their identity.
Schmidt, R. F.↗
On the nonlinear deformation geometry of Euler-Bernoulli beams
Nonlinear expressions are developed to relate the orientation of the deformed beam cross section, torsion, local components of bending curvature, angular velocity, and virtual rotation to deformation variables. The deformed beam kinematic quantities are proven to be equivalent to those derived from various rotation sequences by identifying appropriate changes of variable based on fundamental uniqueness properties of the deformed beam geometry. The torsion variable used is shown to be mathematically analogous to an axial deflection variable commonly used in the literature. Rigorous applicability of Hamilton's principle to systems described by a class of quasi-coordinates that includes these variables is formally established.
Hodges, D. H.↗