A5039749538- Quantum, superfluid, helium dynamics
- Atomic and Subatomic Physics Research
- Spacecraft and Cryogenic Technologies
- Planetary Science and Exploration
- Physics of Superconductivity and Magnetism
- Phase Equilibria and Thermodynamics
- Superconducting Materials and Applications
- Methane Hydrates and Related Phenomena
- Adaptive optics and wavefront sensing
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced MRI Techniques and Applications
- Stellar, planetary, and galactic studies
- Geophysics and Sensor Technology
- High-pressure geophysics and materials
- Astro and Planetary Science
- Advanced Measurement and Metrology Techniques
- Theoretical and Computational Physics
- Superconducting and THz Device Technology
- Spectroscopy and Quantum Chemical Studies
- Astronomy and Astrophysical Research
- Seismic Waves and Analysis
- Advanced Thermodynamics and Statistical Mechanics
- Calibration and Measurement Techniques
- Electron Spin Resonance Studies
- Ionosphere and magnetosphere dynamics
Jet Propulsion Laboratory
2012-2024
California Institute of Technology
1996-2010
University of Bayreuth
2006
University of Southern California
1990-1998
Southern California University for Professional Studies
1995
This review provides an overview of the progress in using low-gravity environment space to explore critical phenomena and test modern theoretical predictions. Gravity-induced variations hydrostatic pressure resulting density gradients adversely affect ground-based measurements near fluid points. Performing a can significantly reduce these difficulties. A number significant experiments have been performed low-Earth orbit. Experiments lambda transition liquid helium explored regime large...
We have measured the initial magnetic suppression of B phase superfluid $^{3}\mathrm{He}$ at pressures from zero to 29 bars. This suppression, which is asymptotically quadratic in field strength, always significantly greater than weak-coupling prediction, even pressure. also provide first values A-phase specific-heat jump for below polycritical point. Microscopic models normal liquid do not conform these experimental constraints. Consequently, it possible that conventional identification...
The difference between total thermodynamic magnetizations in the $A$ and $B$ phases of superfluid ${}^{3}\mathrm{He}$ was measured at equilibrium $A$- transition temperature over entire range applicable magnetic fields pressures from 0 to 27 bars. We present evidence that dynamic measurements (NMR) only partially account for magnetization changes superfluid. experiment also measures nontrivial strong-coupling correction field coupling strength Landau-Ginzburg free energy.
An Inverse Synthetic Aperture LADAR (ISAL) system is capable of providing high resolution surface mapping near Earth objects which an ability that has gained significant interest for both exploration and hazard assessment. The use ISAL over these long distances often presents the need to operate optical in photon-starved conditions. This leads a necessity understand implications photon detector noise system. Here Carrier-to-Noise Ratio derived similar other imaging CNR definitions. value...
In the modern theory of critical phenomena, liquid-vapor density diameter in simple fluids is generally expected to deviate from a rectilinear law approaching point. However, by performing precise scannerlike optical measurements position ${\mathrm{SF}}_{6}$ meniscus, an approach much closer criticality temperature and than earlier measurements, no deviation can be detected. The observed meniscus far ($10\phantom{\rule{0.28em}{0ex}}\mathrm{K}$) extremely close...
We have developed a compact, high-resolution, angle measurement instrument based on heterodyne interferometer. Common-path interferometer metrology is used to measure displacements of reflective target surface. In the set up, an optical mask sample laser beam reflecting back from four areas From relative displacement measurements surface areas, we can simultaneously determine angular rotations around two orthogonal axes in plane perpendicular propagation direction. The device testbed for...
Near the critical point of fluids, opalescence results in light attenuation, or turbidity increase, that can be used to probe universality behavior. Turbidity measurements SF6 under weightlessness conditions on board International Space Station are performed appraise such behavior terms both temperature and density distances from point. Data obtained a range, far (1 K) extremely close (a few μK) phase transition, unattainable previous experiments Earth. analyzed with renormalization-group...
Broadband seismometers and gravitational wave detectors make use of mechanical resonators with a high quality factor to reduce Brownian noise. At low frequency, noise is ultimately dominated by internal friction in the suspension, which has 1/f compared white arising from viscous dissipation. Internal typically modeled as frequency-dependent loss can be challenging measure reliably through experiment. In this work, we present physics experimental implementation electrostatic frequency...
Parametric expressions are used to calculate the isothermal susceptibility, specific heat, order parameter, and correlation length along critical isochore coexistence curve from asymptotic region crossover region. These based on minimal-subtraction renormalization scheme within $\phi^4$ model. Using two adjustable parameters in these expressions, we fit theory globally recently obtained experimental measurements of susceptibility heat curve, early light scattering intensity $^3$He near its...
Future space-based optical interferometers, such as the space interferometer mission (SIM), require thermal stability of wavefront to level picometers in order produce astrometric data at micro-arc-second level. In SIM, internal path will be measured with a small metrology beam whereas starlight fringe position is estimated from large concentric annular beam. To achieve observation goal for it necessary maintain difference between central and outer annulus portions front-end telescope optics...
We present high-resolution measurements of the isothermal susceptibility pure 3He near liquid-gas critical point. PVT were performed in single-phase region over reduced temperature range 3 x 10(-5)<T/Tc-1<1.5 10(-1). The crossover behavior along isochore was analyzed using a field-theoretical renormalization-group calculation based on phi4 model. A similar analysis previously obtained Xe measurements. comparison rescaled for and shows theoretically predicted universal behavior.
A small, high-resolution paramagnetic susceptibility thermometer was developed using a GdCl/sub 3/ salt. The device uses superconducting quantum interference (SQUID) magnetometer to determine the temperature dependent magnetization of salt in magnetic field. field is provided by pair small samarium cobalt permanent magnet disks situated inside housing. This eliminates need for heavy, charging solenoid used conventional SQUID-based system. can resolve approximately 10/sup -9/ K near...