ABSTRACT
Many surfaces found on the Moon, asteroids, Mars, moons, and other planetary bodies are covered in a fine granular material known as regolith. Increased knowledge of the physical properties of extraterrestrial regolith surfaces will help advance the scientific knowledge of these bodies as well as the development of exploration (e.g., instrument and robotic) and in situ resource utilization (ISRU) systems. The Center for Space Resources at the Colorado School of Mines as part of the Institute for Modeling Plasma, Atmospheres, and Cosmic Dust of NASA's Solar System Exploration Research Virtual Institute has developed a novel system, called the ISRU Experimental Probe (IEP) that can support studies of dry and icy regolith from -196 to 150 °C and pressure from laboratory ambient pressure to 10-7 Torr. The IEP system and proof-of-concept results are presented in this paper.
ABSTRACT
The high-temperature, high-pressure, entrained-flow, laboratory-scale gasifier at the Colorado School of Mines, including the primary systems and the supporting subsystems, is presented. The gasifier is capable of operating at temperatures and pressures up to 1650 °C and 40 bar. The heated section of the reactor column has an inner diameter of 50 mm and is 1 m long. Solid organic feedstock (e.g., coal, biomass, and solid waste) is ground into batches with particle sizes ranging from 25 to 90 µm and is delivered to the reactor at feed rates of 2-20 g/min. The maximum useful power output of the syngas is 10 kW, with a nominal power output of 1.2 kW. The initial characterization and demonstration results of the gasifier system with a coal feedstock are also reported.
ABSTRACT
Electronic and structural properties of the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulonyl)imide are studied using density functional theory (DFT) methods in addition to infrared and UV-vis spectroscopy. The DFT methods were conducted for both gas phase and solution phase using the integral equation formalism polarizable continuum model, while optical absorption experiments were conducted using neat and dilute methanol solutions. Three energetically similar conformers were obtained for each of the gas phase and solution phase DFT calculations. These multiple configurations were considered when analyzing the molecular interactions between the ion pair and for a molecular-level interpretation of the experimental IR and UV-vis spectroscopy data. Excitation energies of low-lying singlet excited states of the conformers were calculated with time-dependent DFT and experimentally with UV-vis absorption spectra. Difference density plots and excited-state calculations in the gas phase are found to be in good agreement with the experimental findings, while the implicit solvation model calculations adversely impacted the accuracy of the predicted spectra.
ABSTRACT
Cavity ringdown spectroscopy (CRDS) is a gas sensing technique in which an optical cavity is formed by two or more highly reflective mirrors. Herein we present an overview and historical perspective of CRDS implementations that seek to reduce or eliminate some of the disadvantages of conventional CRDS by modifications to the ringdown cavity (RDC). The hollow waveguide (HWG) CRDS concept that we introduce in this paper reduces some of the disadvantages of conventional CRDS by utilizing a hollow waveguide as the RDC. We develop the basic mathematical theory and model for the HWG-CRDS concept and provide an initial in-depth study of the Bragg waveguide for CRDS applications. We also discuss various aspects of design and performance characteristics of HWG-CRDS, including waveguide attenuation losses with and without gases in the waveguide core, transverse and longitudinal mode propagation behavior, and methods and analysis for the HWG-CRDS excitation.
