Search NASA⌕ Search

SEARCH · Search NASA

Results for “ion transport properties”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Transport properties of ions

The strong long-range interactions between (among) charged species require the inclusion of higher order contributions to the transport properties (viscosity, thermal conductivity, diffusion) of ionized gases than are required for neutral gases. These higher order contributions have been rewritten so that they are given in terms of universal functions which can be tabulated. Tables which provide for the rapid calculation of some higher order contributions to the transport properties of both ions and electrons are given. Some results which are useful for calculating the higher order contributions to the transport properties of mixtures of ions are also given. These results are applied to the ionic species in air at high temperatures.

Biolsi, Louis↗
NASA NTRS2003

Benchmark studies of the effectiveness of structural and internal materials as radiation shielding for the international space station

Accelerator-based measurements and model calculations have been used to study the heavy-ion radiation transport properties of materials in use on the International Space Station (ISS). Samples of the ISS aluminum outer hull were augmented with various configurations of internal wall material and polyethylene. The materials were bombarded with high-energy iron ions characteristic of a significant part of the galactic cosmic-ray (GCR) heavy-ion spectrum. Transmitted primary ions and charged fragments produced in nuclear collisions in the materials were measured near the beam axis, and a model was used to extrapolate from the data to lower beam energies and to a lighter ion. For the materials and ions studied, at incident particle energies from 1037 MeV/nucleon down to at least 600 MeV/nucleon, nuclear fragmentation reduces the average dose and dose equivalent per incident ion. At energies below 400 MeV/nucleon, the calculation predicts that as material is added, increased ionization energy loss produces increases in some dosimetric quantities. These limited results suggest that the addition of modest amounts of polyethylene or similar material to the interior of the ISS will reduce the dose to ISS crews from space radiation; however, the radiation transport properties of ISS materials should be evaluated with a realistic space radiation field. Copyright 2003 by Radiation Research Society.

NASA Discipline Radiation Health↗
NASA NTRS1985

Transport properties for some atom-ion interactions in air

The thermal conductivity and viscosity for the N-N(+) and O-O(+) interactions have been calculated, using the kinetic theory of gases, from 500 K-20,000 K. Accurate spectroscopically determined potentials have been used for the calculations. The results are compared with previous results obtained using less accurate potentials.

Biolsi, L.↗
NASA NTRS1999

Solar Particle Event Exposures and Local Tissue Environments in Free Space and on Martian Surface

Solar particle events (SPEs) are a concern to space missions outside Earth s geomagnetic field. The September 29, 1989 SPE is the largest ground-level event since February 23, 1956. It is an iron-rich event for which the spectra are well measured. Because ten times this event matches the ground level data of the February 1956 SPE, it is suggested that an event with ten-times the scaled spectra of the September 29, 1989 SPE be used as a worst case SPE for spacecraft design. For the worst case SPE, the input spectra were reconstructed using Nymmik's (1995) model for protons, the O and Fe ion spectra of Tylka et al. (1997) to evaluate the iron enhancement ratio, and the Solar Energetic Particle Baseline (SEPB) composition of McGuire et al. (1986) for the heavy ions. The necessary transport properties of the shielding materials and the astronaut s body tissues are evaluated using the HZETRN code. Three shield configurations (assumed to be aluminum) are considered: space suit taken as 0.3 g/sq cm, helmet/pressure vessel as 1 g/sq cm, and equipment room of 5 g/sq cm. A shelter is taken as 10 g/sq cm on the Martian surface. The effect of shielding due to the Martian atmosphere is included. The astronaut geometry is taken from the computerized anatomical man (CAM) model.

Kim, M. Y.↗
NASA NTRS1984

Thermal evaporation of spherical clouds - Effects of viscous stresses

The thermal evaporation of a cold spherical cloud embedded in hot gas is analyzed, including the effects of viscous stresses as well as 'saturation' of the conductive heat flux, for the case of equal electron and ion temperatures. The relevant transport properties for an H-He plasma are discussed, including the modification of these transport coefficients when temperature or velocity gradients become large. The fluid-dynamical equations for steady spherical evaporation are given and cast into dimensinless form. Numerical integration of these equations and the results are discussed, emphasizing the novel features of the viscous solutions, astrophysical implications, and uncertainties in the physics.

Giuliani, J. L., Jr.↗
NASA NTRS1966

Chemical reactions in electrical plasmas.

Chemical kinetics of electron plasma reactions, discussing energy states, ion-molecule reactions, charge transfer, transport properties, phase interactions, etc

ENERGY LEVEL↗
NASA NTRS2015

NASA Space Radiation Program Integrative Risk Model Toolkit

NASA Space Radiation Program Element scientists have been actively involved in development of an integrative risk models toolkit that includes models for acute radiation risk and organ dose projection (ARRBOD), NASA space radiation cancer risk projection (NSCR), hemocyte dose estimation (HemoDose), GCR event-based risk model code (GERMcode), and relativistic ion tracks (RITRACKS), NASA radiation track image (NASARTI), and the On-Line Tool for the Assessment of Radiation in Space (OLTARIS). This session will introduce the components of the risk toolkit with opportunity for hands on demonstrations. The brief descriptions of each tools are: ARRBOD for Organ dose projection and acute radiation risk calculation from exposure to solar particle event; NSCR for Projection of cancer risk from exposure to space radiation; HemoDose for retrospective dose estimation by using multi-type blood cell counts; GERMcode for basic physical and biophysical properties for an ion beam, and biophysical and radiobiological properties for a beam transport to the target in the NASA Space Radiation Laboratory beam line; RITRACKS for simulation of heavy ion and delta-ray track structure, radiation chemistry, DNA structure and DNA damage at the molecular scale; NASARTI for modeling of the effects of space radiation on human cells and tissue by incorporating a physical model of tracks, cell nucleus, and DNA damage foci with image segmentation for the automated count; and OLTARIS, an integrated tool set utilizing HZETRN (High Charge and Energy Transport) intended to help scientists and engineers study the effects of space radiation on shielding materials, electronics, and biological systems.

Kim, Myung-Hee Y.↗
NASA NTRS1987

High temperature transport properties of air

A general computer code was developed to allow calculation of atom-atom and ion-atom transport collision integrals from accurate potential energy curves described by a set of discrete data points for a broad range of scattering conditions. This code is based upon semiclassical approximations that properly account for quantum mechanical behavior such as tunneling effects near a barrier maximum, resonance charge exchange, and nuclear symmetry effects. Transport collision integrals were determined for N-N, O-O, N(+)-N, and O(+)-O interactions from complete sets of accurate potential functions derived from combined experimental and ab initio structure calculations. For the O-O case, this includes results for excited states. The calculated values of the N(+)-N and O(+)-O resonance charge exchange cross section Q(ex) agree well with measurements from beam experiment that are available at high energies where the diffusion cross section Q(d) satisfies Q(d) approximately equal to 2Q(ex).

Levin, E.↗
NASA NTRS1987

Electrochemical performance and transport properties of a Nafion membrane in a hydrogen-bromine cell environment

The overall energy conversion efficiency of a hydrogen-bromine energy storage system is highly dependent upon the characteristics and performance of the ion-exchange membrane utilized as a half-cell separator. The electrochemical performance and transport properties of a duPont Nafion membrane in an aqueous HBr-Br2 environment were investigated. Membrane conductivity data are presented as a function of HBr concentration and temperature for the determination of ohmic voltage losses across the membrane in an operational cell. Diffusion-controlled bromine permeation rates and permeabilities are presented as functions of solution composition and temperature. Relationships between the degree of membrane hydration and the membrane transport characteristics are discussed. The solution chemistry of an operational hydrogen-bromine cell undergoing charge from 45% HBr to 5% HBr is discussed, and, based upon the experimentally observed bromine permeation behavior, predicted cell coulombic losses due to bromine diffusion through the membrane are presented as a function of the cell state-of-charge.

Baldwin, Richard S.↗
NASA NTRS2004

An improved Green's function for ion beam transport

Ion beam transport theory allows testing of material transmission properties in the laboratory environment generated by particle accelerators. This is a necessary step in materials development and evaluation for space use. The approximations used in solving the Boltzmann transport equation for the space setting are often not sufficient for laboratory work and those issues are the main emphasis of the present work. In consequence, an analytic solution of the linear Boltzmann equation is pursued in the form of a Green's function allowing flexibility in application to a broad range of boundary value problems. It has been established that simple solutions can be found for high charge and energy (HZE) ions by ignoring nuclear energy downshifts and dispersion. Such solutions were found to be supported by experimental evidence with HZE ion beams when multiple scattering was added. Lacking from the prior solutions were range and energy straggling and energy downshift with dispersion associated with nuclear events. Recently, we have found global solutions including these effects providing a broader class of HZE ion solutions. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

NASA Center LaRC↗
NASA NTRS2003

An Improved Green's Function for Ion Beam Transport

Ion beam transport theory allows testing of material transmission properties in the laboratory environment generated by particle accelerators. This is a necessary step in materials development and evaluation for space use. The approximations used in solving the Boltzmann transport equation for the space setting are often not sufficient for laboratory work and those issues are the main emphasis of the present work. In consequence, an analytic solution of the linear Boltzmann equation is pursued in the form of a Green's function allowing flexibility in application to a broad range of boundary value problems. It has been established that simple solutions can be found for the high charge and energy (HZE) by ignoring nuclear energy downshifts and dispersion. Such solutions were found to be supported by experimental evidence with HZE ion beams when multiple scattering was added. Lacking from the prior solutions were range and energy straggling and energy downshift with dispersion associated with nuclear events. Recently, we have found global solutions including these effects providing a broader class of HZE ion solutions.

Tweed, J.↗
NASA NTRS2026

Highly Porous Polyimide Gel for Use as Battery Separator with Room Temperature Ionic Liquid Electrolytes

Advanced aerospace vehicular concepts require advances in many existing technologies, including space power and energy storage systems. Batteries represent one of the major areas in need of improvement, both in terms of energy density and safety, with growing concerns over the fire safety of commercial lithium-ion batteries. This has prompted efforts to develop nonflammable battery components, namely the electrolyte and separator. Existing commercial lithium-ion batteries utilize polyolefin microporous membranes as separators with an electrolyte consisting of a lithium salt dissolved in a mixture of cyclic carbonate solvents. This separator/electrolyte combination has ionic conductivities in the range of 10 −2 to 10 −3 S/cm. However, the cyclic carbonate solvents are inherently flammable. Room-temperature ionic liquids (RTILs) appear to be a safer alternative. They offer good ionic conductivities and are inherently nonvolatile and nonflammable, giving them a safety advantage. However, many promising RTILs for battery electrolytes are not compatible with commercial polyolefin separator materials. Alternative separator materials, such as polyimides, are non-flammable and are capable of accepting RTILs into their structure. Polyimide gels, with a composition of 4,4′-oxydianiline, 3,3′,4,4′-tetracarboxylic dianhydride and cross-linked with Desmodur N3300A, possess an open-porous, fibrillar network architecture which offers a high degree of porosity (typically greater than 85% porosity) for lithium-ion transport and conduction, as well as good mechanical properties. Furthermore, these polyimide gels are compatible with selected imidazolium-based RTILs. Nonflammable separator/electrolyte systems with room-temperature conductivities in the range of 10 −3 S/cm have been evaluated. It has been demonstrated that 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide was the most promising among six RTILs screened, in terms of both ionic conductivity and constant current cycling.

Polyimide↗
NASA NTRS1988

Atmospheric Emissions Photometric Imaging (AEPI) experiment

Space plasma physics will be studied on the Atmospheric Laboratory for Applications and Science (ATLAS 1) NASA mission during the Atmospheric Emissions Photometric Imaging (AEPI) experiment. The basic scientific objective of the AEPI is the investigation of the upper atmosphere-ionosphere and the space shuttle environment. The experiment areas of the AEPI include: (1) the investigation of ionospheric transport processes by observing Mg(+) ions; (2) studies of optical properties of artificially induced electron beams; (3) measurement of electron cross sections for selected atmospheric species; (4) studies of natural airglow; and (5) studies of natural auroras. On ATLAS 1, optical emissions generated by the shuttle (shuttle ram glow) will also be investigated.

Mende, S. B.↗