Physics Commons^™

The Effect Of A Tilted Magnetic Field On The Equilibrium Of A Pure Electron Plasma, Grant W. Hart

Faculty Publications

If the magnetic field in a pure electron plasma containment device is not aligned with the axis of the conducting walls, the electrons in the device will accumulate at the ends of the plasma where the magnetic field lines come closest to the walls and the electrons bound to the field lines can be closest to their image charges. If the plasma is also offset radially from the center (as with an l=1 diocotron mode), then more density will accumulate at one end than the other. As the plasma revolves around the center, the electrons will slosh from one end …

Polarization Of Astronomical Maser Radiation, Moshe Elitzur

Physics and Astronomy Faculty Publications

The polarization of maser radiation when the source is permeated by an aligned magnetic field is derived for arbitrary angular momenta of the transition states. This generalization is made possible by an analysis of the structure of the propagating waves in a frame aligned with the magnetic axis. The key elements in determining the polarization properties are the assumption of independent and incoherent pump and loss processes for all magnetic sublevels, and the beaming of maser radiation. The radiation propagating in the direction of maximal intensity growth is polarized according to the solutions derived by Goldreich, Keeley, and Kwan for …

Fluctuations In Astronomical Masers, Moshe Elitzur

Physics and Astronomy Faculty Publications

The radiation of astronomical masers fluctuates on the time scale 1/Gamma, where Gamma is the levels' loss rate. These intensity fluctuations reflect fluctuations of the level poulations around their mean, steady state values over the length scale λ_c = c/Γ. In saturated masers, the intensity fluctuations are dominated by passage through the unsaturated core. The effects of the saturated zones and of the seed radiation that the masers amplify can be neglected.

These fluctuations may have been detected in recent observations by Clegg and Cordes (1991) of Galactic H II/OH masers, providing a possible direct determination of the …

Theory Of An Atomic Beam Splitter Based On Velocity-Tuned Resonances, Scott Glasgow, P. Meystre, M. Wilkens, E. M. Wright

Faculty Publications

We develop the theory of an atomic beam splitter in which a monoenergetic beam of two-level atoms is incident normally to a classical standing-wave light field. The incident atomic wave function can be split into two coherent components with transverse momenta ±(2n + 1)fzk using velocity-tuned resonances, where n is the order of the resonance. We discuss the cases of zero- and first-order resonances in detail, and show that the velocity-tuned resonances are renormalized due to a high-frequency Stark shift. Numerical results that display the effects of a finite momentum spread in the incident atomic beam are presented.

Radiative Transfer In Astronomical Masers. Iii. Filamentary Masers, Moshe Elitzur, Christopher F. Mckee, David J. Hollenbach

Physics and Astronomy Faculty Publications

This paper, the last in a series, presents the complete solution of a filamentary maser. The contribution of rays emanating from the filament sidewall is essential for the solution self-consistency during saturation. We develop an integral equation to calculate this contribution, devise an iteration scheme to solve it, and perform the first two iterations. The solution provides complete expressions for the distributions of intensity and flux across the source as functions of position and direction with regard to the axis. One consequence of radiation beaming, somewhat surprising at first, is that the filament appears smaller when viewed off-axis, at angles …

A Search For Embedded Young Stellar Objects In And Near The Ic 1396 Complex, Richard Schwartz, Bruce Wilking, Armen Giulbudagian

Physics Faculty Works

The IRAS data base is used to locate young stellar object candidates in and near the IC 1396 complex located in the Cepheus OB2 association. Co-added survey data are used to identify all sources with a flux density Snu(100) greater than 10 Jy and with Snu(100) greater than Snu(60). The 15 sources located at the positions of globules and dark clouds are further analyzed using the in-scan slices to assess the source profiles

Diffuse Band Profiles In The Spectrum Of Hd 29647: Evidence For A Molecular Origin?, Theodore P. Snow, C G. Seab

Physics Faculty Publications

High signal-to-noise ratio spectra have been obtained of the diffuse interstellar bands at 5780 and 5797 Å in the spectrum of HD 29647, a heavily reddened star within or behind a portion of the Taurus dark cloud complex. The observations were made using the coudé spectrograph on the Canada-France-Hawaii Telescope. The Reticon detector combined with the coudé spectrograph and excellent observing conditions allowed S/N ratios as high as 200 for this star, which was V=8.37 and E(B–V)=1.03. In two separate exposures both bands were found to be narrower and weaker than normal values for …

Nonequilibrium Processes In Polymers Undergoing Interchange Reactions. Part 2: Reaction-Diffusion Processes, Alejandro Garcia, J. Pojman, D. Kondepudi, C. Van De Broeck

Faculty Publications

A reactiodffusion system of polymers undergoing interchange reactions is studied. The equation that describes the dynamics of the system is similar to the Boltzmann equation for a gas of hard spheres. We consider a one-dimensionsl system in which the average length and the concentrations at the boundaries are fixed. The resulting steady states are obtained analytically and with numerical integration of equations obtained by using a local equilibrium approximation. Monte Carlo simulations of experimentally realizable conditions were performed and compared. The results reveal a nonlinear distribution of molecular concentration and mass. The entropy of the polymer distributions is calculated as …

Forbidden Lines Of Np^Q Ions. Ii. Line Intensities, J. P. Lynch, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

Ground state forbidden transitions of np^q ions of C, N, 0, Ne, Mg, Si, S, and Fe can provide important information on the state of cosmic ionized gases. Wavelengths of these lines are in the far- and near-UV visible and near- and far-IR regions of the spectrum. The line intensity ratios of particular transitions in q = 2, 4 ions can provide information on the temperature of the gas and in q = 3 ions information on the density of the gas. In the present work we have tabulated the line intensities of 95 transitions of these ions, which include …

Structure And Optical Characterization Of Znxcd1-Xte Thin Films Prepared By The Close Spaced Vapor Transport Method, David D. Allred, Jesus González-Hernández, O. Zelaya, J. G. Mendoza-Alverez, E. López-Cruz, D. A. Pawlik

Faculty Publications

Zinc cadmium telluride (ZnxCd1-xTe) solid solution films with 0≤x≤0.12 were deposited by the close spaced vapor transport method and characterized using photoluminescence, x-ray diffraction, and scanning electron microscopy. The two former techniques indicate that films with high crystalline quality can be prepared with moderate substrate temperatures and low argon pressures. Under these conditions deposition rates of up to 1000 Å/s are achieved and Zn concentration in the film is the same as that of the source. The electron micrographs show grain sizes comparable to the film thickness.

The Transmittances Of Thin Polymer Films And Their Suitability As A Supportive Substrate For A Soft X-Ray Solar Filter, Memorie Williams, Evan Hansen, A. Reyes-Mena, David D. Allred

Faculty Publications

This paper discusses soft x-ray filter designs for the Brigham Young University "Goldhelox Project". Three polymers intended for use as a supportive substrate for a soft x-ray solar filter, having a passband centered at 171 angstroms are examined. The use of polymer substrates is examined because of vibrational and mechanical stresses associated with the shuttle launch, preventing the use of a free standing filter, and because of Goldhelox's special need to locate the filter near the imaging plane. The uniform consistency of a polymer support will prevent any imaging of the filter support structure, as would occur if a traditional …