Measurement of NO plus plus e minus dissociative recombination in expanding air flows

Measurement of nitric oxide ion-electron dissociative recombination in expanding air flow

Sources of electron energy in weakly ionized expansions of nitrogen

Sources of electron energy in weakly ionized expansions of nitroge

Catalysis of hydrogen-atom recombination in rocket nozzles

Oxygen and oxygen-nitrogen mixtures as catalysts for hydrogen atom recombination in rocket nozzle

Characteristics of the motions, turbulence intensity, diffusivity, flux of momentum and sensible heat in the upper atmosphere

Analyses of the meteorological rocket data obtained from an experiment conducted at 3-hour intervals at 8 western meridional rocket stations are presented. Large variations in the meridional wind contribute substantially to overall turbulence in the tropical stratosphere. The solar semidiurnal component of wind oscillations in the tropics was observed to be much higher than predicted by theory, often exceeding the magnitude of the diurnal amplitude throughout the stratosphere. The observed value of the solar diurnal amplitude in the stratosphere was in line with theoretical prediction. The solar terdiurnal amplitudes for temperature, meridional and zonal winds were non-negligible and must be considered in any harmonic analysis. Phase angle variation with height was rapid for all harmonics; however, there was general agreement between predicted and observed phase angles. Because of large changes in the mean winds in the mesosphere with season, harmonic determinations are difficult. There appear to be large zonal wind changes even within the same season as mentioned previously. Turbulence diffusivity in the upper stratosphere is greater near the equator than in the mid-latitudes

On the transonic aerodynamics of a compressor blade row

Linearized analyses have been carried out for the induced velocity and pressure fields within a compressor blade row operating in an infinite annulus at transonic Mach numbers of the flow relative to the blades. In addition, the relationship between the induced velocity and the shape of the mean blade surface has been determined. A computational scheme has been developed for evaluating the blade mean surface ordinates and surface pressure distributions. The separation of the effects of a specified blade thickness distribution from the effects of a specified distribution of the blade lift has been established. In this way, blade mean surface shapes that are necessary for the blades to be locally nonlifting have been computed and are presented for two examples of blades with biconvex parabolic arc sections of radially tapering thickness. Blade shapes that are required to achieve a zero thickness, uniform chordwise loading, constant work spanwise loading are also presented for two examples. In addition, corresponding surface pressure distributions are given. The flow relative to the blade tips has a high subsonic Mach number in the examples that have been computed. The results suggest that at near-sonic relative tip speeds the effective blade shape is dominated by the thickness distribution, with the lift distribution playing only a minor role

Estimates of nonequilibrium ionization phenomena in the inviscid Apollo plasma sheath

Nonequilibrium ionization in asymmetric plasma sheath determined for Apollo spacecraft at superorbital velocity reentr

A Quantum Theory of Temporally Mismatched Homodyne Measurements with Applications to Optical Frequency Comb Metrology

The fields of precision timekeeping and spectroscopy increasingly rely on optical frequency comb interferometry. However, comb-based measurements are not described by existing quantum theory because they exhibit both large mode mismatch and finite strength local oscillators. To establish this quantum theory, we derive measurement operators for homodyne with arbitrary mode overlap. These operators are a combination of quadrature and intensity-like measurements, which inform a filter that maximizes the quadrature measurement signal-to-noise ratio. Furthermore, these operators establish a foundation to extend frequency-comb interferometry to a wide range of scenarios, including metrology with nonclassical states of light.Comment: 5 pages plus appendice

The performance of random bosonic rotation codes

Bosonic error correcting codes utilize the infinite dimensional Hilbert space of a harmonic oscillator to encode a qubit. Bosonic rotation codes are characterized by a discrete rotation symmetry in their Wigner functions and include codes such as the cat and binomial codes.We define two different notions of random bosonic rotation codes and numerically explore their performance against loss and dephasing. We find that the best random rotation codes can outperform cat and binomial codes in a certain parameter regime where loss is large and dephasing errors are small.Comment: 9 Pages, 9 Figs, Reuploaded to fix incorrect figure generatio

First principles calculation of point defects and mobility degradation in bulk AlSb for radiation detection application

The development of high resolution, room temperature semiconductor radiation detectors requires the introduction of materials with increased carrier mobility-lifetime ({mu}{tau}) product, while having a band gap in the 1.4-2.2 eV range. AlSb is a promising material for this application. However, systematic improvements in the material quality are necessary to achieve an adequate {mu}{tau} product. We are using a combination of simulation and experiment to develop a fundamental understanding of the factors which affect detector material quality. First principles calculations are used to study the microscopic mechanisms of mobility degradation from point defects and to calculate the intrinsic limit of mobility from phonon scattering. We use density functional theory (DFT) to calculate the formation energies of native and impurity point defects, to determine their equilibrium concentrations as a function of temperature and charge state. Perturbation theory via the Born approximation is coupled with Boltzmann transport theory to calculate the contribution toward mobility degradation of each type of point defect, using DFT-computed carrier scattering rates. A comparison is made to measured carrier concentrations and mobilities from AlSb crystals grown in our lab. We find our predictions in good quantitative agreement with experiment, allowing optimized annealing conditions to be deduced. A major result is the determination of oxygen impurity as a severe mobility killer, despite the ability of oxygen to compensation dope AlSb and reduce the net carrier concentration. In this case, increased resistivity is not a good indicator of improved material performance, due to the concomitant sharp reduction in {mu}{tau}