• Vittrup Sloan posted an update 6 months, 2 weeks ago

    Preliminary data are presented to demonstrate the operation of the apparatus and to illustrate the types of fluid dynamic information that can be captured.A repetitive electron beam driver based on 6-stage Linear Transformer Driver (LTD) cavities is presented. Each cavity consists of two Blumlein pulse forming networks (BPFNs) sharing a laser trigger switch. Voltage adding is obtained by means of Linear Transformer (LT) technology. The LTD cavity consists of two BPFNs connected in parallel, an LT with a ratio of 11, and a laser-triggered spark switch. check details The energy efficiency of a single LTD was investigated. The results show that the energy efficiency of an L-type BPFN and an LT was 94.3% and 92.8%, respectively. An electron beam driver consisting of 6 such cavities was developed with an output voltage of 740 kV, a current of 12.3 kA, and a power of 9.1 GW. The repetition frequency operation results show that the electron beam driver can operate stably for 20 s at 25 Hz with a jitter of approximately 1.7 ns.A versatile, temperature controlled apparatus is presented, which generates deeply cooled liquid microjets of condensed gases, expelling them via a small aperture into vacuum for use in photoelectron spectroscopy (PES). The functionality of the design is demonstrated by temperature- and concentration-dependent PES measurements of liquid ammonia and solutions of KI and NH4I in liquid ammonia. The experimental setup is not limited to the usage of liquid ammonia solutions solely.The small saturation energy density of excimers requires amplifiers of large cross sections for amplification of short pulses of already medium power. Homogeneous excitation of large volumes of fluorine-based gas mixtures by discharge pumping is a critical interplay of the properties of both pumping and preionization, generally necessitating an intense spatially and temporally controlled x-ray preionization. In the present realization, the stringent intensity requirements of preionization are fulfilled by reducing the pulse duration of the x-ray flash to ∼16 ns and by positioning the x-ray source in the near vicinity of the active volume. It is proven both theoretically and experimentally that by proper choice of the positions of two cylindrical x-ray guns, the spatial distribution of preionization can be tuned to (and around) the optimum distribution. In this way, the spatial distribution of the discharge can also be controlled, giving a practical method to compensate for eventual inhomogenities of the E-field of excitation and to tune the discharge to the desired geometry. In this paper, design considerations and experimental realization of a KrF excimer amplifier of ∼5 × 4 cm2 cross section and a spatially tunable x-ray preionization are presented.A remote temperature sensing technique was developed by measuring exponential decay current pulses in a Helmholtz coil. After an initial calibration to extract a mathematical function relating the time constant (τ) to the temperature of the object sensed, the temperature of other similar objects can be estimated with less power, less strict positioning of the object, and more sensitivity than previous techniques, even inside a water-based fluid.A line VISAR (Velocity Interferometer System for Any Reflector) has been designed and commissioned at the Sandia National Laboratory’s Z-machine. The instrument consists of an F/2 collection system, beam transport, and an interferometer table that contains two Mach-Zehnder type interferometers and an eight channel Gated Optical Imaging (GOI) system. The VISAR probe laser operates at the 532 nm wavelength, and the GOI bandpass is 540-600 nm. The output of each interferometer is passed to an optical streak camera with four selectable sweep speeds. The system is designed with three interchangeable optics modules to select a full field of view of 1 mm, 2 mm, or 4 mm. The optical beam transport system connects the target image plane to the interferometers and the gated optical imagers. The target is integrated into a sacrificial final optics assembly that is integral to the transport beamline.Measurement of the phase behavior and (meta)stability of liquid formulations, including surfactant solutions, is required for the understanding of mixture thermodynamics, as well as their practical utilization. We report a microfluidic platform with a stepped temperature profile, imposed by a dual Peltier module, connected to an automated multiwell plate injector and optical setup, for rapid solution phase mapping. The measurement protocol is defined by the temperature step ΔT ≡ T1 – T2 (≲100 °C), volumetric flow rate Q ≡ ΔV/Δt (≲50 μl/min), which implicitly set the thermal gradient ΔT/Δt (≃0.1-50 °C/min), and measurement time (which must exceed the intrinsic timescale of the relevant phase transformation). Furthermore, U-shaped microchannels can assess the reversibility of such transformations, yielding a facile measurement of the metastable zone width of the phase diagram. By contrast with traditional approaches, the platform precisely controls the cooling and heating rates by tuning the flow rate, and the absolute temperature excursion by the hot and cold thermal profile, which remain stationary during operation, thus allowing the sequential and reproducible screening of large sample arrays. As a model system, we examined the transition from the micellar (L1) to the liquid crystalline lamellar phase (Lα), upon cooling, of aqueous solutions of sodium linear alkylbenzene sulfonate, a biodegradable anionic surfactant extensively employed in industry. Our findings are validated with quiescent optical microscopy and small angle neutron scattering data.Herein, we report a significant improvement in the medium- to long-term frequency stability of our pulsed optically pumped (POP) vapor-cell rubidium clock. Such an achievement is established with the better control of our system and the environment. An integrated optical module, including a distributed Bragg reflector laser and an acousto-optic modulator, is developed to improve the stability of the laser. The physics package is sealed in a vacuum chamber with a vacuum of 4 × 10-4 Pa to significantly reduce the impacts of the barometric effect. An AC-driven heater is placed much closer to the cell to enable a better temperature control. The resolution of the servo control voltage is also optimized. With all these improvements, a frequency stability of 4.7 × 10-15 at 104 s in terms of the Allan deviation is obtained. We also estimate the main noise sources that limit the frequency stability of the POP atomic clock.

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