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  1. Plasma-based water purification involves the transport of reactive species across the gas–liquid interface. This process is limited by slow diffusion driven mass transport of reactive species across the interface. Additionally, the plasma gas–liquid contact area is typically limited, contributing to reduced dose delivery. These key factors make it difficult to scale up the treatment process to input flows of industrial interest. In this work, turbulence is explored as a means to introduce a fine grain structure, thus greatly increasing the interfacial surface area, leading to large property gradients and more efficient mass transport. Such a fine scale structure can also enhance the local electric field. The test apparatus explored in this work is the packed bed reactor that places thin water jets into contact with plasma. It is theorized that introducing turbulence, via increasing Reynolds number in such thin jets, may enhance the effective plasma dose at fixed plasma power. In this work, changes in the flow regime, from laminar to turbulent, of water jets in a packed bed water reactor (PBR) configuration are investigated experimentally. Methylene blue dye, a model contaminant, was tested in the PBR to demonstrate enhanced treatment via reduced treatment times. Plasma surface morphology around themore »jets noticeably changed with the flow regime, and turbulent flow demonstrated a faster hydrogen peroxide uptake, along with slower temperature, electrical conductivity, and a pH change in a batch treatment process, compared to laminar flow. The dye was destroyed significantly faster in the turbulent flow, indicating an increased effective plasma dose.« less
    Free, publicly-accessible full text available March 7, 2024
  2. IMECE2022-88299 Midwest Engineered Systems Inc. has created a novel laser wire metal deposition process, ADDere manufacturing. ADDere has a much higher deposition rate than powder bed fusion, making it ideal for large components. In this project, the mechanical properties of ADDere printed materials were tested and compared to typical values found in ASM publications to show the quality of materials manufactured by the ADDere printing process. A detailed material analysis was performed on samples made from Ti-6Al-4V and 17-4 PH stainless steel. This work builds upon an earlier study of samples made from 17-4 PH that were produced using a single direction pattern. In this project, the 17-4 PH samples were printed in a cross hatched pattern, and testing results were compared to existing data from single direction samples of the previous research. The Ti-6Al-4V samples were created in two builds. One using the uni-directional method and the other with the crossed pattern. Testing specimens were removed from the samples using a water jet cutter and further machined into ASTM tensile bars and metallurgic mounts to perform a thorough material evaluation. The Ti-6Al-4V sample met the expected values in the ASM literature, and the cross hatched 17-4 PH exhibited amore »higher hardness and better microstructure than the single direction samples from the previous work. It was also observed that when the Ti64 samples were manufactured in the cross hatched pattern, the properties indicated slight improvement and more homogeneity than those printed in single layer direction. The obtained results indicate that ADDere’s printing process can produce highly refined materials that are customizable with their expected uses. This work showcases an excellent industry collaboration of an undergraduate research experience.« less
    Free, publicly-accessible full text available November 1, 2023
  3. Exploring dark matter via observations of extreme astrophysical environments -- defined here as heavy compact objects such as white dwarfs, neutron stars, and black holes, as well as supernovae and compact object merger events -- has been a major field of growth since the last Snowmass process. Theoretical work has highlighted the utility of current and near-future observatories to constrain novel dark matter parameter space across the full mass range. This includes gravitational wave instruments and observatories spanning the electromagnetic spectrum, from radio to gamma-rays. While recent searches already provide leading sensitivity to various dark matter models, this work also highlights the need for theoretical astrophysics research to better constrain the properties of these extreme astrophysical systems. The unique potential of these search signatures to probe dark matter adds motivation to proposed next-generation astronomical and gravitational wave instruments. Note: Contribution to Snowmass 2021 -- CF3. Dark Matter: Cosmic Probes
  4. Abstract The Van Allen Probes Electric Fields and Waves (EFW) instrument provided measurements of electric fields and spacecraft floating potentials over a wide dynamic range from DC to 6.5 kHz near the equatorial plane of the inner magnetosphere between 600 km altitude and 5.8 Re geocentric distance from October 2012 to November 2019. The two identical instruments provided data to investigate the quasi-static and low frequency fields that drive large-scale convection, waves induced by interplanetary shock impacts that result in rapid relativistic particle energization, ultra-low frequency (ULF) MHD waves which can drive radial diffusion, and higher frequency wave fields and time domain structures that provide particle pitch angle scattering and energization. In addition, measurements of the spacecraft potential provided a density estimate in cold plasmas ( $<20~\text{eV}$ < 20 eV ) from 10 to $3000~\text{cm}^{-3}$ 3000 cm − 3 . The EFW instrument provided analog electric field signals to EMFISIS for wave analysis, and it received 3d analog signals from the EMFISIS search coil sensors for inclusion in high time resolution waveform data. The electric fields and potentials were measured by current-biased spherical sensors deployed at the end of four 50 m booms in the spacecraft spin plane (spin period $\sim11~\text{sec}$ ∼ 11 secmore ») and a pair of stacer booms with a total tip-tip separation of 15 m along the spin axis. Survey waveform measurements at 16 and/or 32 S/sec (with a nominal uncertainty of 0.3 mV/m over the prime mission) were available continuously while burst waveform captures at up to 16,384 S/sec provided high frequency waveforms. This post-mission paper provides the reader with information useful for accessing, understanding and using EFW data. Selected science results are discussed and used to highlight instrument capabilities. Science quantities, data quality and error sources, and analysis routines are documented.« less
    Free, publicly-accessible full text available December 1, 2023
  5. Abstract Magnetized plasma interactions are ubiquitous in astrophysical and laboratory plasmas. Various physical effects have been shown to be important within colliding plasma flows influenced by opposing magnetic fields, however, experimental verification of the mechanisms within the interaction region has remained elusive. Here we discuss a laser-plasma experiment whereby experimental results verify that Biermann battery generated magnetic fields are advected by Nernst flows and anisotropic pressure effects dominate these flows in a reconnection region. These fields are mapped using time-resolved proton probing in multiple directions. Various experimental, modelling and analytical techniques demonstrate the importance of anisotropic pressure in semi-collisional, high- β plasmas, causing a reduction in the magnitude of the reconnecting fields when compared to resistive processes. Anisotropic pressure dynamics are crucial in collisionless plasmas, but are often neglected in collisional plasmas. We show pressure anisotropy to be essential in maintaining the interaction layer, redistributing magnetic fields even for semi-collisional, high energy density physics (HEDP) regimes.
  6. We have developed a low-cost approach for accurately measuring short-term vertical motions of the seafloor and maintaining a continuous long-term record of seafloor pressure without the requirement for costly ship time. We equipped the University of Hawai‘i Liquid Robotics Wave Glider with an integrated acoustic telemetry package, a dual-frequency geodetic-grade global positioning system (GPS) receiver, meteorological pressure sensor, processing unit, and cellular communications. The Wave Glider interrogates high accuracy pressure sensors on the seafloor to retrieve their pressure and temperature data. We correct the seafloor pressure measurements using sea surface kinematic GPS location and atmospheric pressure data collected by the Wave Glider payload. By combining the concurrent seafloor and sea surface observations, we demonstrate the capability to provide timely, continuous, and high-accuracy estimation and monitoring of centimeter-scale vertical seafloor motions.