Investigation of slosh anomaly in Apollo lunar module propellant gage

Analysis of propellant sloshing in lunar module during Apollo 14 flight and resultant erroneous indication of low level of propellan

Automatic closed circuit television arc guidance control Patent

Automatic closed circuit television arc guidance control for welding joint

Excimer lasers

The results of a two-year investigation into the possibility of developing continuous wave excimer lasers are reported. The program included the evaluation and selection of candidate molecular systems and discharge pumping techniques. The K Ar/K2 excimer dimer molecules and the xenon fluoride excimer molecule were selected for study; each used a transverse and capillary discharges pumping technique. Experimental and theoretical studies of each of the two discharge techniques applied to each of the two molecular systems are reported. Discharge stability and fluorine consumption were found to be the principle impediments to extending the XeF excimer laser into the continuous wave regime. Potassium vapor handling problems were the principal difficulty in achieving laser action on the K Ar/K2 system. Of the four molecular systems and pumping techniques explored, the capillary discharge pumped K Ar/K2 system appears to be the most likely candidate for demonstrating continuous wave excimer laser action primarily because of its predicted lower pumping threshold and a demonstrated discharge stability advantage

Spin accumulation in forward-biased MnAs/GaAs Schottky diodes

We describe a new means for electrically creating spin polarization in semiconductors. In contrast to spin injection of electrons by tunneling through a reverse-biased Schottky barrier, we observe spin accumulation at the metal/semiconductor interface of forward-biased ferromagnetic Schottky diodes, which is consistent with a theory of spin-dependent reflection off the interface. Spatiotemporal Kerr microscopy is used to image the electron spin and the resulting dynamic nuclear polarization that arises from the non equilibrium carrier polarization.Comment: 13 pages, 4 figures, submitted for publicatio

Metallicity of Red Giants in the Galactic Bulge from Near-Infrared Spectroscopy

We present K-band spectra of more than 110 M giants in Galactic bulge fields interior to -4 degrees and as close as 0.2 degrees of the Galactic Center. From the equivalent widths of three features in these spectra, EW(Na),EW(Ca), and EW(CO) we calculate [Fe/H] for the stars with a calibration derived from globular clusters Stephens et al (2000). The mean [Fe/H] for each field is in good agreement with the results from Frogel et al. (1999) based on the slope of the giant branch method. We find no evidence for a metallicity gradient along the minor or major axes of the inner bulge (R < 0.6 kpc). A metallicity gradient along the minor axis, found earlier, arises when fields located at larger galactic radius are included. However, these more distant fields are located outside of the infrared bulge defined by the COBE/DIRBE observations. We compute the [Fe/H] distribution for the inner bulge and find a mean value of -0.21 dex with a full width dispersion of 0.30 dex, close to the values found for Baade's Window (BW) by Sadler et al. (1996) and to a theoretical prediction for a bulge formed by dissipative collapse Molla et al (2000).Comment: 32 pages, 10 figures, AJ submitte

Excimer lasers

A theoretical and experimental investigation into the possibility of achieving CW discharge pumped excimer laser oscillation is reported. Detailed theoretical modeling of capillary discharge pumping of the XeF and KXe and K2 excimer systems was carried out which predicted the required discharge parameters for reaching laser threshold on these systems. Capillary discharge pumping of the XeF excimer system was investigated experimentally. The experiments revealed a lower excimer level population density than predicted theoretically by about an order of magnitude. The experiments also revealed a fluorine consumption problem in the discharge in agreement with theory

Impurity Band Conduction in a High Temperature Ferromagnetic Semiconductor

The band structure of a prototypical dilute ferromagnetic semiconductor, Ga$_{1-x}$Mn$_{x}$As, is studied across the phase diagram via optical spectroscopy. We prove that the Fermi energy ($E_{F}$) resides in a Mn induced impurity band (IB). This conclusion is based upon careful analysis of the frequency and temperature dependence of the optical conductivity ($\sigma_{1}(\omega,T)$). From our analysis of $\sigma_{1}(\omega,T)$ we infer a large effective mass ($m^*$) of the carriers, supporting the view that conduction occurs in an IB. Our results also provide useful insights into the transport properties of Mn-doped GaAs.Comment: 4 pages, 4 figure

Closed-circuit television welding- electrode guidance system

Closed-circuit TV camera is mounted parallel to electrode and moves along with it. Camera is scanned along seam so seam is viewed parallel with scan lines on TV monitor. Two fiber optics illuminators are attached to guidance system; they illuminate seam for TV camera