SEARCH · Engineering Papers

Results for “Resonator”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20

All sources NASA NTRS DOE OSTI

NASA NTRS1973

Effects of resonant tesseral gravity coefficients on Viking-type orbits.

A special perturbation technique has been developed for the long-period and secular motion of a Viking-type orbiter. The technique uses a method of singly averaging the perturbations over the mean anomaly to determine changes in orbital elements due to atmospheric drag, solar radiation pressure, solar gravity, and the asymmetrical Mars gravitational field. The technique has been specialized to treat resonant tesseral gravity effects resulting from the commensurability of the satellite orbit period with the rotational period of the primary. Results are presented which indicate that orbiter lifetimes can be significantly reduced by resonant tesserals for orbits near the critical inclination. Conversely, it is shown that lifetimes can be extended via capture in resonant orbits which are stable against small drag forces.

Compton, H. R.↗

NASA NTRS1973

Resonances and librations of some Apollo and Amor asteroids with the Earth.

The orbital evolution of the Apollo asteroids 1620 Geographos and 1685 Toro and Amor asteroids 433 Eros, 1221 Amor, and 1627 Ivar are investigated by numerical integration. All these asteroids, with the exception of Geographos, exhibit systematic orbital couplings with the Earth during the time interval studied (1600-2350 A.D.). 1685 Toro is captured into libration once with Venus due to the 13.5 resonance, and once with the Earth due to the 8:5 resonance. Both librations are unstable because of the effect of the 13:8 near commensurability of the Venus-Earth system. 433 Eros exhibits no libration pattern; the regular variation of its orbital period is due to the beat-effect of the 4:7 resonance with the Earth.

Ip, W.-H.↗

NASA NTRS1973

Finite-aperture waveguide-laser resonators.

A general theory of finite-aperture waveguide-laser resonators is developed which represents the external reflectors by matrices that couple linearly polarized waveguide modes having the same azimuthal symmetry. The theory allows the determination of resonator efficiency, resonator frequencies, and laser near- and far-field patterns. Computations of the coupling loss for the fundamental waveguide mode as a function of mirror curvature, separation, and aperture are in good agreement with recent infinite-aperture calculations in the limit of large apertures and indicate three low-loss configurations: (1) large radius of curvature mirrors close to the guide; (2) large radius of curvature mirrors centered at the guide entrance; and (3) generally smaller curvature mirrors separated by half their curvature from the guide entrance.

Degnan, J. J.↗

NASA NTRS1973

Resonant oscillations of intermediate frequency in a stratified atmosphere.

A class of solutions to a model of forced oscillations in a rotating stratified atmospheric layer is derived and analyzed. The basic model is found to reduce to a boundary value problem with a second-order linear partial differential equation of the hyperbolic type for this range of forcing frequencies. The forced solutions are shown to exhibit resonances with the normal modes of oscillation of the layer. The characteristics of the resonant modes are analyzed in terms of mean tropospheric values of temperature, temperature lapse, wind speed, horizontal and vertical wind shears, latitude, and the frequency and horizontal wavelength of the forcing mechanism. These solutions are compared with solutions to the model for a different (subinertial) range of forcing frequencies. This comparison leads to an elliptic boundary value problem. The solutions in that case do not exhibit the same type of resonance and generally decay away from the region of forcing.

Thompson, O. E.↗

NASA NTRS1973

A new ion and electron detector for ion cyclotron resonance spectroscopy.

A new detector using an extremelly driven tuned circuit has been developed for use in ion cyclotron resonance spectroscopy experiments. Based on the Q-meter circuit, this detector will operate at frequencies greater than 1 MHz at rf levels less than 1 mV. Operation in the frequency range 1-15 MHz allows the use of higher magnetic fields for more efficient storage of low mass ions in the trapping mode of operation. In the frequency range 2-6 MHz electrons can be detected in the ion cyclotron resonance cell by their resonant motion in the trapping plane.

Huntress, W. T., Jr.↗

NASA NTRS1973

Effects of size, shape, and frequency on the antiferromagnetic resonance linewidth of MnF

The research concerning the properties and application of solid state materials at submillimeter frequencies is summarized. Work reported includes: far infrared Fourier spectroscopy; studies of the antiferromagnetic resonance line in MnF2 at millimeter wavelengths; numerical solution of the equations of motion of a general two-sublattice antiferromagnet; study of antiferromagnetic resonance line in NiO powder; and resonance investigations of several indium thisospinels at millimeter wavelengths.

Obrien, K. C.↗

NASA NTRS1973

Analytical and experimental study of resonance ignition tubes

The application of the gas-dynamic resonance concept was investigated in relation to ignition of rocket propulsion systems. Analytical studies were conducted to delineate the potential uses of resonance ignition in oxygen/hydrogen bipropellant and hydrazine monopropellant rocket engines. Experimental studies were made to: (1) optimize the resonance igniter configuration, and (2) evaluate the ignition characteristics when operating with low temperature oxygen and hydrogen at the inlet to the igniter.

Stabinsky, L.↗

NASA NTRS1973

Resonances observed on mother-daughter rocket flights in the ionosphere

Resonance phenomena have been observed in swept frequency experiments carried out on two mother-daughter Nike-Tomahawk rocket flights at auroral latitudes. The experimental method is briefly described and characteristic samples of the results are presented. A possible interpretation of some main resonances is offered, involving cold plasma cone resonances.

Folkestad, K.↗

NASA NTRS1974

Open and Closed Loop Stability of Hingeless Rotor Helicopter Air and Ground Resonance

The air and ground resonance instabilities of hingeless rotor helicopters are examined on a relatively broad parametric basis including the effects of blade tuning, virtual hinge locations, and blade hysteresis damping, as well as size and scale effects in the gross weight range from 5,000 to 48,000 pounds. A special case of a 72,000 pound helicopter air resonance instability is also included. The study shows that nominal to moderate and readily achieved levels of blade inertial hysteresis damping in conjunction with a variety of tuning and/or feedback conditions are highly effective in dealing with these instabilities. Tip weights and reductions in pre-coning angles are also shown to be effective means for improving the air resonance instability.

Young, M. I.↗

NASA NTRS1973

Semiprecision calculations of electron-hydrogen resonances

Results of a calculation of the lowest (1 S) resonance below the first excitation threshold in electron-hydrogen scattering. This calculation is based on a precision Hylleraas calculation of the resonant wave function, combined with various reasonable physically motivated approximations for the nonresonant continuum. These approximations are basically the exchange- and polarized-orbital approximations. The values obtained, together with previous results obtained for the two higher (3 P and 1 D) resonances, are compared with the previous most accurate calculations, and some differences are noted.

Bhatia, A. K.↗

NASA NTRS1973

A new effect in the depolarization of resonant light scattering from molecules in the vapor phase: I2

Theoretical discussions of the depolarization ratios in two types of resonance processes are given. These processes are discrete state resonance fluorescence, and Raman scattering when the resonance is between a bound state and evanescent-dissociative states. Theory predicts a dramatic difference for these two cases due to a quantum mechanical phase cancellation in the case of virtual dissociative states. The predictions have been verified experimentally.

Silverstein, S. D.↗

NASA NTRS1973

Valence resonance states of N2/-/

Resonant scattering observed in the transmission of electrons between 9 and 11 eV in collision with N2 has been attributed to the attachment of the scattered electron to an excited valence state. Resonance valence excited states of N2(-) are calculated that could support this hypothesis. Although calculated and observed resonance energies are in close agreement, the calculations do not reflect the observed complex angular behavior of the scattered electron.

Krauss, M.↗

NASA NTRS1974

A resonance phenomenon observed in a swept frequency experiment on a mother-daughter ionospheric rocket

The report presents observations obtained in a swept frequency experiment conducted in a mother-daughter rocket flight at auroral latitudes. The discussion is essentially restricted to the possible interpretation of the experimental signal structures noted at and in the vicinity of a resonance frequency where signal components apparently are generated by nonlinear mechanisms. Various resonance frequencies have been considered in attempts to identify this multichannel response frequency. It is concluded that of all the possibilities invoked, the best consistency is provided by identifying the frequency concerned with the cone resonance frequency demonstrated experimentally in the case of a laboratory plasma by Fisher and Gould (1971).

Folkestad, K.↗

NASA NTRS1974

Application of the Brown-Shook model to the Kirkwood gaps and resonant asteroids

The mathematical model developed by Brown and Shook is used to explain the absence of asteroids in the Kirkwood gaps as well as the existence of some resonant asteroids with orbital periods commensurable to that of Jupiter. In addition, this model can possibly explain the biased number distributions at the commensurable positions of both resonant gaps and clusters. However, this resonant model is probably not applicable to the Saturnian ring system due to the possible cosmogonic plasma process during its formation.

Ip, W. H.↗

NASA NTRS1974

Eleventh-order geopotential resonance on the orbit of Vanguard 3

The orbit of Vanguard 3 (1959-7A) is strongly resonant with eleventh-order and odd degree terms in the geopotential. It affords an excellent opportunity to determine a significant linear constraint between these terms. Tracking data on this satellite (in the form of mean Kepler elements) are analyzed over a 3.5-year period in the early 1960s, which ends with the orbit having just passed through perfect commensurability. The eccentricity e and inclination I show the deep resonance variations (up to .0002 in e and 0.02 deg in I) with great clarity. Previous and current geopotential solutions fail to explain these perturbations. A constraint for the deep resonant terms is determined in fully normalized harmonics.

Wagner, C. A.↗

NASA NTRS1974

Pre-resonance Raman spectra of some simple gases

The pre-resonance Raman spectra of SO2, N2O, and H2S were investigated using the 4880 A, 4727 A, and 4579 A lines of the argon ion laser. Although these molecules have electronic absorption bands in the near ultraviolet, none exhibit any pre-resonance enhancement within our experimental error of + or - 10%. Possible explanations taking into account the current theories for resonance Raman are discussed.

Low, P. W.↗

NASA NTRS1975

Resonance lines of Cs II, Ba III, and La IV

The resonance line spectra of ions in the Xe I isoelectronic sequence, consisting of the five transitions to the 5p6 150 ground state from levels with J = 1 in the 5p5 5d and 6s configurations, have been observed for Cs II, Ba III, and La IV. The observations were made with a sliding spark on the 10.7-m normal-incidence vacuum spectrograph at NBS. The resonance transitions from the 5p5 6d and 7s configurations were also observed for these ions, except for that from 5p5 6d 3P1 of Ba III. Several resonance transitions from higher nd and ns levels were also observed. Estimated values for the J = 1 levels of the 5p5 7s configuration of Ce V were obtained by extrapolation. The derived ionization energies in eV are Cs II 23.17(4), Ba III 35.79(6), La IV 45.95(6), Ce V 65.55(25).

Reader, J.↗

NASA NTRS1975

The resonant orbit of the Lost City meteorite

An integration of the long-period perturbations of Jupiter and Saturn on the orbit of the Lost City meteorite shows that the average nodal rate of the meteorite was nearly the same as the nodal rates of Jupiter and Saturn. This near equality of rates led to a large resonant variation in the inclination of the meteorite's orbit with a period on the order of 1 million years. The resonance makes the orbital evolution too sensitive to the deficiencies of the perturbation calculations and to the values of the elements at impact to allow definitive calculations. It is shown that an orbit similar to the meteorite's orbit can spend approximately 88% of its time with an eccentricity too small to allow for intersections with the earth's orbit. The ordinary cosmic ray exposure age of the Lost City meteorite does not suggest that its collisional lifetime was unusual, but the role of resonances in determining the lifetime of typical meteorites is unknown.

Williams, J. G.↗