Current pathways model for hall thruster plumes in ground-based vacuum test facilities: measurements and observations.

A previous companion paper introduced a current pathways model that represents the electrical coupling between the Hall effect thruster (HET) and the ground-based vacuum test facility operational environment. In this work, we operated a 7-kW class HET at 4.5 kW, 15 A and 6 kW, 20 A on krypton to quantify aspects of the current pathways model to characterize the role metal vacuum chambers play in the thruster's discharge circuit as a function of discharge current.

Using plasma-activated water for decontamination of Salmonella spp. on common building surfaces in poultry houses.

Plasma-activated water (PAW) has been shown to have antimicrobial properties, making it a promising tool for surface decontamination. This study evaluated the ability of PAW generated from high voltage atmospheric cold plasma to remove Salmonella from common surfaces (stainless steel (SS), polyvinyl chloride (PVC), concrete, and wood) found in poultry houses. PAW was generated by exposing distilled water to atmospheric cold plasma in 80% humid air at 90 kV and 60 Hz for 30 min.

Hall effect thruster impedance characterization in ground-based vacuum test facilities.

Hall effect thrusters (HETs) are typically regarded as DC electric propulsion devices as they are operated with isolated DC power supplies. However, it is well known that the HET's discharge current possesses oscillations of varying magnitudes and frequencies and is thus a function of time with AC characteristics. The observed oscillations are caused by plasma processes associated with ion, electron, and neutral particle dynamics that occur inside the HET's discharge channel and in the plume as the HET electrically interacts with its local operating environment.

Bayesian plasma model selection for Thomson scattering.

Laser Thomson scattering (LTS) is a measurement technique that can determine electron velocity distribution functions in plasma systems. However, accurately inferring quantities of interest from an LTS signal requires the selection of a plasma physics submodel, and comprehensive uncertainty quantification (UQ) is needed to interpret the results. Automated model selection, parameter estimation, and UQ are particularly challenging for low-density, low-temperature, potentially non-Maxwellian plasmas like those created in space electric propulsion devices.

Pregelatinized Drum-Dried Wheat Starch of Different Swelling Behavior as Clean Label Oil Replacer in Oil-in-Water Emulsions.

Drum-drying results in pregelatinized starch with relatively low starch fragmentation and a great ability to absorb water and swell at room temperature. However, the effect of the degree of cold particle swelling and the thickening potential of drum-dried starch on its suitability as oil replacer in low-fat oil-in-water emulsions has received little attention. In this work, the potential of three pregelatinized drum-dried starches with almost identical molecular structure (as measured by size exclusion chromatography) and Water Binding Capacity (WBC), but different swelling behavior, was investigated to replace up to 60% oil in a mayonnaise-like emulsion system.

Bayesian framework for THz-TDS plasma diagnostics.

Terahertz time-domain spectroscopy (THz-TDS) is an optical diagnostic used to noninvasively measure plasma electron density and collision frequency. Conventional methods for analyzing THz-TDS plasma diagnostic data often do not account for measurement artifacts and do not quantify parameter uncertainties. We introduce a novel Bayesian framework that overcomes these deficiencies.

ELECTROMAGNETICALLY INDUCED DISTORTION OF A FIBRIN MATRIX WITH EMBEDDED MICROPARTICLES.

Blood clots occur in the human body when they are required to prevent bleeding. In pathological states such as diabetes and sickle cell disease, blood clots can also form undesirably due to hypercoagulable plasma conditions. With the continued effort in developing fibrin therapies for potential life-saving solutions, more mechanical modeling is needed to understand the properties of fibrin structures with inclusions.

Maize leaf PPDK regulatory protein isoform-2 is specific to bundle sheath chloroplasts and paradoxically lacks a Pi-dependent PPDK activation activity.

In C4 plants, the pyruvate phosphate dikinase regulatory protein (PDRP) regulates the C4 pathway enzyme pyruvate phosphate dikinase (PPDK) in response to changes in incident light intensity. In maize (Zea mays) leaves, two distinct isoforms of PDRP are expressed, ZmPDRP1 and ZmPDRP2. The properties and C4 function of the ZmPDRP1 isoform are well understood.

Recommended Practice for Thrust Measurement in Electric Propulsion Testing.

Accurate, direct measurement of thrust or impulse is one of the most critical elements of electric thruster characterization, and one of the most difficult measurements to make. This paper summarizes recommended practices for the design, calibration, and operation of pendulum thrust stands, which are widely recognized as the best approach for measuring N- to mN-level thrust and Ns-level impulse bits. The fundamentals of pendulum thrust stand operation are reviewed, along with the implementation of hanging pendulum, inverted pendulum, and torsional balance configurations.

rf power system for thrust measurements of a helicon plasma source.

A rf power system has been developed, which allows the use of rf plasma devices in an electric propulsion test facility without excessive noise pollution in thruster diagnostics. Of particular importance are thrust stand measurements, which were previously impossible due to noise. Three major changes were made to the rf power system: first, the cable connection was changed from a balanced transmission line to an unbalanced coaxial line.

Peripheral ocular aberrations in mild and moderate keratoconus.

Purpose: To investigate the influence of keratoconus on peripheral ocular aberrations.

Methods: Aberrations in seven mild and five moderate keratoconics were determined over a 42° horizontal × 32° vertical visual field, with a modified aberrometer. Control data were obtained from an emmetropic group.

High-power, null-type, inverted pendulum thrust stand.

This article presents the theory and operation of a null-type, inverted pendulum thrust stand. The thrust stand design supports thrusters having a total mass up to 250 kg and measures thrust over a range of 1 mN to 5 N. The design uses a conventional inverted pendulum to increase sensitivity, coupled with a null-type feature to eliminate thrust alignment error due to deflection of thrust.