Satellite Frequencies Research Articles

PAC study on111Cd in antiferromagnetic CuO

400 keV111In+ ions were implanted into CuO powder. After annealing at 570 K, more than 50% of the implants were found on substitutional sites in the monoclinic CuO lattice. PAC-spectra taken below the Neel temperatureTN≈230 K revealed a broadening of the quadrupole spectrum and additional satellite frequencies caused by combined electric and magnetic hyperfine interaction. Assuming that the orientation of the electric field gradient is given by the point charge model and taking the 〈010〉 direction of the supertransferred fieldBtr in CuO from neutron diffraction, we find a Larmor frequency of ωL≈40 MHz corresponding toBtr≈2.7 T at 60 K.

Gravitomagnetic interaction and laser ranging to Earth satellites.

The contribution of the ``gravitomagnetic'' interaction to a well-measured perturbation term in the orbits of Earth satellites is calculated. Laser-ranging determination of the Moon's orbit and Lageos-satellite orbit require the precise participation of the gravitomagnetic interaction; otherwise anomalous orbital perturbations exist. For the Lageos-satellite orbit, the gravitomagnetic interaction's contribution to the orbit is a 100-m altitude variation of frequency \ensuremath{\omega}-\ensuremath{\Omega} (\ensuremath{\omega} and \ensuremath{\Omega} are satellite and Earth orbital angular frequencies, respectively), but which is nullified by effects from other well established post-Newtonian gravitational potentials.

Emergent markets for orbit spectrum assignments: An idea whose time has come

Market-type forces increasingly appear in contests for space satellite frequencies and positions in the geostationary orbit. This article examines the latest moves of advanced satellite companies to gain access to the orbit spectrum by the help of other countries. Company mergers to combine transponder capacity with transmission rights are also examined. The author discusses the buying and selling of terrestrial spectrum and orbital broadcast slots, with particular reference to the US and UK markets.

Yearly variations of rain-rate statistics at Wallops Island and their impact on modeled slant path attenuation distributions

Rain gauge measurements at Wallops Island, VA over a five-year period have been reduced and cumulative rain-date distributions have been determined for yearly, successively combined years, and overall average cases. Yearly variations of the predicted slant path attenuation statistics for two International Radio Consultative Committee (CCIR) models (referred to as modified method I and method II) and the global model at 28.56 GHz were calculated using the yearly measured rain rates at Wallops Island. This frequency was selected as it coincided with the beacon frequency of the COMSTAR geostationary satellite which was also simultaneously monitored at Wallops Island for a period of three years enabling a comparison with the measured rain-fade statistics. The year to year variations of the predicted fades as well as the percent deviations relative to the five-year average case were examined.

Analytic vortices and magnetic resonances in rotating superfluidHe3−AII.

The earlier analysis of the vortex lattices in rotating $^{3}\mathrm{He}\ensuremath{-}A$ is extended to lower temperatures. It is shown that, contrary to the earlier assertion, the observed satellite frequencies lie in between those associated with the circular and the hyperbolic vortices when the temperature-dependent corrections are properly included. Therefore, we conclude that the vortex lattice of the circular-hyperbolic type is indeed realized in the Helsinki experiment.

Temporally and spatially resolved plasma satellites in a hollow-cathode source

Observations of the temporal dependence of plasma satellites to the forbidden component of He I 447 nm in a hollow-cathode source show, firstly, that the satellite intensities can exceed the forbidden component intensity and secondly, that, for a brief period, the near-satellite intensity increases by the same amount as the far-satellite intensity decreases. A splitting of the forbidden component was observed when the frequency separation of the satellites and forbidden component reached half the value of the separation between the allowed and forbidden components. The satellite frequencies observed along the symmetry axis in the negative glow as well as in the dark spaces (below spiking threshold) are constant.

Domain walls inHe3−Ain a parallel-plate geometry

Pure $\stackrel{^}{l}$ domain walls in superfluid $^{3}\mathrm{He}$ confined between two parallel plates with gap $d$ ($\ensuremath{\sim}{\ensuremath{\xi}}_{\ensuremath{\perp}}$, the dipole coherence length) are considered theoretically. The spatial conformation of the domain wall as well as the domain-wall energy are determined. The domain walls give rise to satellite resonances in NMR experiments. The satellite frequencies are determined.

Composite solitons inHe3-Ain the presence of superflow

We have studied theoretically the effect of superflow on the composite solitons in $^{3}\mathrm{He}$-$A$ for $\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}\ensuremath{\parallel}{\stackrel{\ensuremath{\rightarrow}}{\mathrm{v}}}_{s}$ and $\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}\ensuremath{\perp}{\stackrel{\ensuremath{\rightarrow}}{\mathrm{v}}}_{s}$. Here $\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}$ is a static magnetic field and ${\stackrel{\ensuremath{\rightarrow}}{\mathrm{v}}}_{s}$ is the superfluid velocity. The domain-wall energy as well as related NMR satellite frequencies are determined as functions of ${v}_{s}$. In the parallel geometry ($\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}\ensuremath{\parallel}{\stackrel{\ensuremath{\rightarrow}}{\mathrm{v}}}_{s}$), we predict hysteresis in the satellite frequencies when the superfluid velocity ${v}_{s}$ is changed, due to the existence of two branches of stable textures. In both configurations there exist critical velocities ${v}_{s}(\ensuremath{\lesssim}1 \mathrm{mm}/sec)$, at which the domain-wall energy becomes negative indicating the global instability of the uniform texture.

Observation of the Simultaneous Additive Effect of Several Xenon Perturbers on the Cs6s−9pDoublet

Multiple satellites appear in absorption spectra on both components of the Cs $6s\ensuremath{-}9p$ doublet perturbed by xenon at densities of the order of ${10}^{19}$ atoms/${\mathrm{cm}}^{3}$. The profiles of these perturbed lines computed with the Anderson-Talman theory, and the density dependence of the absorption at the multiple satellite frequencies, definitely identify the origin of the satellites as the combined additive effect of one to four perturbers.

Field-induced surface texture in 3He-A in the presence of superflow

The effect of superflow on the magnetic field-induced surface texture in /sup 3/He-A is studied theoretically. We find that in the presence of small superflow the surface texture becomes nonplanar. The NMR satellite frequencies associated with the surface texture are obtained.

MATH]-TEXTURE EFFECTS ON MAGNETIC RESONANCE IN SUPERFLUID 3He

We calculate the effects on the satellite frequencies in NMR due to the changes in spatial variation length scale of the [MATH] vector.

Bound spin-wave states associated withn→solitons in superfluidHe3−B

Extending an earlier work on $\stackrel{\ensuremath{\rightarrow}}{\mathrm{n}}$ solitons in superfluid $^{3}\mathrm{He}\ensuremath{-}B$, we study in greater details the bound spin-wave states trapped by the $\stackrel{\ensuremath{\rightarrow}}{\mathrm{n}}$ soliton. The NMR satellite frequencies, intensities, and widths of these satellites are determined.

Composite solitons and magnetic resonance in superfluidHe3−A. II

A recent study on composite solitons in $^{3}\mathrm{He}\ensuremath{-}A$ is extended to more general configurations and to all temperatures. The texture free energy and the NMR satellite frequencies are determined. In particular, the satellite frequency associated with the splay composite soliton appears to account for the transverse satellite observed by Gould and Lee.

Planarl^textures and magnetic resonances in superfluidHe3-A

The three typical planar $\stackrel{^}{l}$ textures in the presence of magnetic fields and currents are studied. Their texture profiles, energies, and associated magnetic resonance satellite frequencies are calculated. We propose that the splay $\stackrel{^}{l}$ texture is responsible to the transverse satellite observed by Gould and Lee in their magnetic resonance experiment.

Double-Peaked Longitudinal and Transverse NMR Spectra in SuperfluidHe3−A

New NMR resonances in bulk /sup 3/He-A have been investigated. These appear in both longitudinal and transverse modes as small satellites on the low-frequency sides of the already-well-studied resonances predicted by theory. It is found that the satellite frequencies in the two modes have slightly different temperature dependences. It is also found that the satellites are enhanced by rapid temperature changes and are suppressed in a confined geometry. (AIP)

Beat frequency waves in an experiment on the interaction between a low frequency instability and an RF field near the LHR

Plasma waves at the beat or satellite frequencies f+or-=f0+or-f' are excited by the application of an r.f. field (with frequency f0) to a plasma column in which there pre-exists an instability (at a frequency f' approximately 100 kHz). The behaviour of the pump and satellite waves near the l.h.r. is investigated. Radial profiles of the r.f. potential amplitude and phase for the waves are obtained for a range of pump frequencies between 1 and 20 MHz.

Spectres interatomiques induits. Bandes satellites “bleues” observees pres des raies d'absorption atomiques en presence de gaz rares—I aspect experimental

We give an empirical expression for calculation of the blue satellite frequencies as functions of the perturbing-atom densities and temperatures, as well as of the polarizabilities and masses of the atoms present. This expression is discussed in view of a large number of experimental results, most of which are unpublished.

Behavioural Dimorphism in Male Ruffs, Philomachus Pugnax (L.)

Behavioural Dimorphism in Male Ruffs, Philomachus Pugnax (L.)

Trapped-Particle Instability

A simple model for a new instability resulting from particles trapped in a large-amplitude electrostatic wave is invoked to explain the generation of satellite frequencies in a recently reported experiment by Wharton, Malmberg, and O'Neil. The model predicts satellites on the large-amplitude wave at a frequency separation proportional to $\sqrt{E}$, where $E$ is the amplitude of the large wave. The predicted growth rates reasonably account for the observed growth of these satellites.

Satellite resonances and librations associated with Tesseral harmonics of the geopotential

The motion of a satellite under the influence of the longitude-dependent terms of the geopotential is examined in a frame of reference rotating with the mean motion of the satellite. The orbits are assumed to be near-circular but unrestricted with respect to inclination. In general the effect of the tesseral harmonics is to induce short-period perturbations of small amplitude. Under special conditions, however—when the satellite's mean motion is commensurable with the earth's rotation—two distinct types of resonance may be set up. The physical behavior, as well as the mathematical description, of the motion is inherently different in the separate resonances. Specifically, dynamical resonances occur when the impressed frequency due to some Jnm term is equal to the natural frequency of the satellite's orbital motion. In this case the amplitude of the induced oscillation builds up with time, the eccentricity increases, and the orbit is unstable in the sense that it will be driven out of the resonance state. For other commensurabilities librational resonances occur when the satellite is in a localized potential well in the moving frame. In this situation the periodic motion of the satellite in the potential trough is analogous to pendulum motion. In turn, this manifests itself as a long-period libration in longitude of the satellite's ground track. For near-equatorial motion, only the 24-hour orbit is librational; the orbits in dynamical resonance are confined to the range from 12 to 48 hours, clustering around but not including the 24-hour orbit.