Drive system employing frictionless bearings including superconducting matter

A device employing frictionless bearings including a mass of superconductor material having a superconducting temperature Tc above about 77° K, magnet having an axis of symmetry being levitated from said mass of superconductor material so as to be rotatable about its axis of symmetry, and a support member attached to the magnet. The support member is driven so as to cause the magnet to rotate about its axis of symmetry. It also includes a frictionless commutator where a signal beam is intermittently interrupted by a member attached to the magnet, the support member being driven so as to cause the magnet to rotate about its axis of symmetry

Impact Broadening, Shifting, and Asymmetry of the D1 and D2 Lines of Alkali-Metal Atoms Colliding With Noble-Gas Atoms

The Anderson Talman theory of spectral line broadening is used together with potential energy curves calculated at the spin-orbit multi-reference configuration interaction level to compute broadening, shifting, and asymmetry coefficients of the D1 and D2 lines of alkali-metal atoms M, as they collide with noble gas atoms N, where M=K, Rb, and Cs, and N=He, Ne, and Ar. Our calculated coefficients are compared to experimental results for a variety of temperatures. In all cases general agreement is observed for the broadening coefficients, while significant disagreement is observed for the shifting coefficients. We also compare our K+He broadening and shifting results with fully quantum-mechanical calculations that employ the Baranger theory of collisional line broadening, and we compare our results with other semiclassical calculations. As with the comparison to experiment, closer agreement is observed for the broadening coefficients while the shifting coefficients exhibit significant disagreement. We use the natural variation between the difference potentials of the nine M+N pairs to explore the relationship between potential and line shape as determined by Anderson-Talman theory and develop a picture for the mechanism that underlies the general agreement between theoretical and experimental results on the broadening coefficient and the general disagreement on shifting coefficients

A Fully Quantum Calculation of Broadening and Shifting Coefficients of the D\u3csub\u3e1\u3c/sub\u3e and D\u3csub\u3e2\u3c/sub\u3e spectral lines of alkali-metal atoms colliding with noble-gas atoms

We use the Baranger model to compute collisional broadening and shift rates for the D1 and D2 spectral lines of M + Ng, where M = K, Rb, Cs and Ng = He, Ne, Ar. Scattering matrix elements are calculated using the channel packet method, and non-adiabatic wavepacket dynamics are determined using the split-operator method together with a unitary transformation between adiabatic and diabatic representations. Scattering phase shift differences are weighted thermally and are integrated over temperatures ranging from 100 K to 800 K. We find that predicted broadening rates compare well with experiment, but shift rates are predicted poorly by this model because they are extremely sensitive to the near-asymptotic behavior of the potential energy surfaces. © 2020 The Author(s). Published by IOP Publishing Ltd

Kinetics of High Pressure Argon-helium Pulsed Gas Discharge

Simulations of a pulsed direct current discharge are performed for a 7% argon in helium mixture at a pressure of 270 Torr using both zero- and one-dimensional models. Kinetics of species relevant to the operation of an optically pumped rare-gas laser are analyzed throughout the pulse duration to identify key reaction pathways. Time dependent densities, electron temperatures, current densities, and reduced electric fields in the positive column are analyzed over a single 20 μs pulse, showing temporal agreement between the two models. Through the use of a robust reaction rate package, radiation trapping is determined to play a key role in reducing Ar(1s5) metastable loss rates through the reaction sequence Ar(1s5)+e− → Ar(1s4)+e− followed by Ar(1s4) → Ar + ℏω⁠. Collisions with He are observed to be responsible for Ar(2p9) mixing, with nearly equal rates to Ar(2p10) and Ar(2p8) ⁠. Additionally, dissociative recombination of Ar2+ is determined to be the dominant electron loss mechanism for the simulated discharge conditions and cavity size

Effect of Ar(3p\u3csup\u3e5\u3c/sup\u3e4p; 2p)+M -\u3e Ar(3p\u3csup\u3e5\u3c/sup\u3e4s; 1s)+M branching ratio on optically pumped rare gas laser performance

Optically pumped rare gas laser performance is analyzed as a function of the Ar(3p54p; 2p) + M → Ar(3p54s; 1s) + M branching ratios. Due to the uncertainty in the branching ratios, a sensitivity study is performed to determine the effect on output and absorbed pump laser intensities. The analysis is performed using a radio frequency dielectric barrier discharge as the source of metastable production for a variety of Argon in Helium mixtures over pressures ranging from 200 to 500 Torr. Peak output laser intensities show a factor of 7 increase as the branching ratio is increased from 0.25 to 1.00. The collection of Ar* in Ar(1s4) is inversely proportional to the branching ratio and decreases output laser intensity by reducing the density of species directly involved with lasing

Analytic Non-adiabatic Derivative Coupling Terms for Spin-orbit MRCI Wavefunctions. I. Formalism

Analytic gradients of electronic eigenvalues require one calculation per nuclear geometry, compared to at least 3n + 1 calculations for finite difference methods, where n is the number of nuclei. Analytic nonadiabatic derivative coupling terms (DCTs), which are calculated in a similar fashion, are used to remove nondiagonal contributions to the kinetic energy operator, leading to more accurate nuclear dynamics calculations than those that employ the Born-Oppenheimer approximation, i.e., that assume off-diagonal contributions are zero. The current methods and underpinnings for calculating both of these quantities, gradients and DCTs, for the State-Averaged MultiReference Configuration Interaction with Singles and Doubles (MRCI-SD) wavefunctions in COLUMBUS are reviewed. Before this work, these methods were not available for wavefunctions of a relativistic MRCI-SD Hamiltonian. Calculation of these terms is critical in successfully modeling the dynamics of systems that depend on transitions between potential energy surfaces split by the spin-orbit operator, such as diode-pumped alkali lasers. A formalism for calculating the transition density matrices and analytic derivative coupling terms for such systems is presented

M + Ng Potential Energy Curves Including Spin-orbit Coupling for M = K, Rb, Cs and Ng = He, Ne, Ar

X2Σ+1/2 ⁠, A2Π1/2, A2Π3/2, and B2Σ+1/2 potential energy curves and associated dipole matrix elements are computed for M + Ng at the spin-orbit multi-reference configuration interaction level, where M = K, Rb, Cs and Ng = He, Ne, Ar. Dissociation energies and equilibrium positions for all minima are identified and corresponding vibrational energy levels are computed. Difference potentials are used together with the quasistatic approximation to estimate the position of satellite peaks of collisionally broadened D2 lines. The comparison of potential energy curves for different alkali atom and noble gas atom combinations is facilitated by using the same level of theory for all nine M + Ng pairs

Influence of Basis-set Size on the X\u3csup\u3e2\u3c/sup\u3eΣ\u3csup\u3e+\u3c/sup\u3e\u3csub\u3e1/2\u3c/sub\u3e, A\u3csup\u3e2\u3c/sup\u3eΠ\u3csub\u3e1/2\u3c/sub\u3e, A\u3csup\u3e2\u3c/sup\u3eΠ\u3csub\u3e3/2\u3c/sub\u3e, and B\u3csup\u3e2\u3c/sup\u3eΣ\u3csub\u3e1/2\u3c/sub\u3e potential-energy curves, A\u3csup\u3e2\u3c/sup\u3eΠ\u3csub\u3e3/2\u3c/sub\u3e 2 vibrational energies, and D\u3csub\u3e1\u3c/sub\u3e and D\u3csub\u3e2\u3c/sub\u3e line shapes of Rb+He

The X 2 Σ + 1 / 2 , A 2 Π 1 / 2 , A 2 Π 3 / 2 , and B 2 Σ + 1 / 2 potential-energy curves for Rb+He are computed at the spin-orbit multireference configuration interaction level of theory using a hierarchy of Gaussian basis sets at the double-zeta (DZ), triple-zeta (TZ), and quadruple-zeta (QZ) levels of valence quality. Counterpoise and Davidson-Silver corrections are employed to remove basis-set superposition error and ameliorate size-consistency error. An extrapolation is performed to obtain a final set of potential-energy curves in the complete basis-set (CBS) limit. This yields four sets of systematically improved X 2 Σ + 1 / 2 , A 2 Π 1 / 2 , A 2 Π 3 / 2 , and B 2 Σ + 1 / 2 potential-energy curves that are used to compute the A 2 Π 3 / 2 bound vibrational energies, the position of the D 2 blue satellite peak, and the D 1 and D 2 pressure broadening and shifting coefficients, at the DZ, TZ, QZ, and CBS levels. Results are compared with previous calculations and experimental observation

Metastable Ar(1s\u3csub\u3e5\u3c/sub\u3e) Density Dependence on Pressure and Argon-helium Mixture in a High Pressure Radio Frequency Dielectric Barrier Discharge

Simulations of an α-mode radio frequency dielectric barrier discharge are performed for varying mixtures of argon and helium at pressures ranging from 200 to 500 Torr using both zero and one-dimensional models. Metastable densities are analyzed as a function of argon-helium mixture and pressure to determine the optimal conditions, maximizing metastable density for use in an optically pumped rare gas laser. Argon fractions corresponding to the peak metastable densities are found to be pressure dependent, shifting from approximately 15% Ar in He at 200 Torr to 10% at 500 Torr. A decrease in metastable density is observed as pressure is increased due to a diminution in the reduced electric field and a quadratic increase in metastable loss rates through Ar*2 formation. A zero-dimensional effective direct current model of the dielectric barrier discharge is implemented, showing agreement with the trends predicted by the one-dimensional fluid model in the bulk plasma

Space Station Freedom automation and robotics: An assessment of the potential for increased productivity

This report presents the results of a study performed in support of the Space Station Freedom Advanced Development Program, under the sponsorship of the Space Station Engineering (Code MT), Office of Space Flight. The study consisted of the collection, compilation, and analysis of lessons learned, crew time requirements, and other factors influencing the application of advanced automation and robotics, with emphasis on potential improvements in productivity. The lessons learned data collected were based primarily on Skylab, Spacelab, and other Space Shuttle experiences, consisting principally of interviews with current and former crew members and other NASA personnel with relevant experience. The objectives of this report are to present a summary of this data and its analysis, and to present conclusions regarding promising areas for the application of advanced automation and robotics technology to the Space Station Freedom and the potential benefits in terms of increased productivity. In this study, primary emphasis was placed on advanced automation technology because of its fairly extensive utilization within private industry including the aerospace sector. In contrast, other than the Remote Manipulator System (RMS), there has been relatively limited experience with advanced robotics technology applicable to the Space Station. This report should be used as a guide and is not intended to be used as a substitute for official Astronaut Office crew positions on specific issues