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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.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

LET spectra measurements of charged particles in the P0006 experiment on LDEF

Measurements are under way of the charged particle radiation environment of the Long Duration Exposure Facility (LDEF) satellite using stacks of plastic nuclear track detectors (PNTD's) placed in different locations of the satellite. In the initial work the charge, energy, and linear energy transfer (LET) spectra of charged particles were measured with CR-39 double layer PNTD's located on the west side of the satellite (Experiment P0006). Primary and secondary stopping heavy ions were measured separately from the more energetic particles. Both trapped and galactic cosmic ray (GCR) particles are included, with the latter component being dominated by relativistic iron particles. The results from the P0006 experiment will be compared with similar measurements in other locations on LDEF with different orientation and shielding conditions. The remarkably detailed investigation of the charged particle radiation environment of the LDEF satellite will lead to a better understanding of the radiation environment of the Space Station Freedom. It will enable more accurate prediction of single event upsets (SEU's) in microelectronics and, especially, more accurate assessment of the risk - contributed by different components of the radiation field (GCR's, trapped protons, secondaries and heavy recoils, etc.) - to the health and safety of crew members.

Benton, E. V.↗
NASA NTRS1998

A Coupled Plasma Dynamics and Gas Flow Model for Semiconductor Processing

A continuum modeling approach by self-consistently coupling plasma dynamics and gas flow will be presented for the analysis of high density plasma reactors. Experimental data shows that gas flow distribution affects the etch rate uniformity even at low pressures (6-20 mTorr) and flow rates (20-70 sccm). This study will investigate the effects of gas flow and gas energy on bulk plasma densities and temperatures using a continuum model. The model solves multidimensional equations of mass balance for neutrals and ions, gas momentum, separate energy equations for electrons and neutrals and Maxwell's equations for power coupling. A test case of N2 plasma in a 300mm TCP etch reactor, for which hybrid model and Langmuir probe data are available, is chosen for this analysis. Our preliminary results show that modeling gas flow and energy improves the predictions of electron density and its spatial variation in the reactor when compared with the experimental data. The aim of this study is to identify the operating conditions for the TCP reactor when a self-consistent modeling of gas flow is important.

Bose, Deepak↗
NASA NTRS1986

Method and apparatus for rebalancing a redox flow cell system

A rebalance cell is provided for a REDOX electrochemical system of the type having anode and cathode fluids which are aqueous HCl solutions with two metal species in each. The rebalance cell has a cathode compartment and a chlorine compartment separated by an ion permeable membrane. By applying an electrical potential to the rebalance cell while circulating cathode fluid through the cathode compartment and while circulating an identical fluid through the chlorine compartment, any significant imbalance of the REDOX system is prevented.

Gahn, Randall F.↗
NASA NTRS2016

Cold Ion Demagnetization near the X-line of Magnetic Reconnection

Although the effects of magnetic reconnection in magnetospheres can be observed at planetary scales, reconnection is initiated at electron scales in a plasma. Surrounding the electron diffusion region, there is an Ion-Decoupling Region (IDR) of the size of the ion length scales (inertial length and gyroradius). Reconnection at the Earths magnetopause often includes cold magnetospheric (few tens of eV), hot magnetospheric (10 keV), and magnetosheath (1 keV) ions, with different gyroradius length scales. We report observations of a subregion inside the IDR of the size of the cold ion population gyroradius (approx. 15 km) where the cold ions are demagnetized and accelerated parallel to the Hall electric field. Outside the subregion, cold ions follow the E x B motion together with electrons, while hot ions are demagnetized. We observe a sharp cold ion density gradient separating the two regions, which we identify as the cold and hot IDRs.

Toledo-Redondo, Serio↗
NASA NTRSDate not supplied

Microcalorimeter Absorber Optimization for 0.2 to 12 keV X-Rays

The Advanced Telescope for High ENergy Astrophysics (ATHENA) mission requires high quantum efficiency (QE) x-ray absorption, >90.6% at 7 keV and low specific heat capacity, 0.731 pJ/K. The designed ATHENA x-ray absorbers are cantilevered square tiles (pitch of 317 microns) of 1.05 μm thick Au and 5.51 μm thick Bi electroplated films supported by stems that connect the absorber to the detector below. We discuss some of the methods used to produce x-ray absorbers meeting these specifications for ATHENA. To tune the thermal conductance of the device and the effect on the normal-to superconducting transition shape, the stems need to be small diameter and can have a weak bottle-neck connection to the substrate. A funnel shape of the stem using a proximity exposed photoresist mold has been developed to improve the strength of the connections. Further requirements on the absorbers include low levels of fine particulate remaining on the substrate after production and zero shorts between absorbers due to incomplete ion milling or trapped fine particular between absorbers. To optimize for post patterning substrate cleanliness and absorber yield, we have examined several methods of absorber fabrication. Three such methods are 1) an ion mill/wet etch combination, 2) a photoresist mold for electroplating followed by wet or dry etch to remove the seed layer, and 3) an electroplating process with leveling to smooth the surface followed by ion mill to separate the absorbers. The different combinations of wet and dry etches lead to different yields and surface appearance of the absorber sidewalls. We present results on the achieved pixel yields and the energy resolution of pixels made with the various fabrication methods. We discuss the impact of absorber patterning method on performance, uniformity, and yield.

Edward J Wassell↗
NASA NTRS1993

Vorticity equation for MHD fast waves in geospace environment

The MHD vorticity equation is modified in order to apply it to nonlinear MHD fast waves or shocks when their extent along the magnetic field is limited. Field-aligned current (FAC) generation is also discussed on the basis of this modified vorticity equation. When the wave normal is not aligned to the finite velocity convection and the source region is spatially limited, a longitudinal polarization causes a pair of plus and minus charges inside the compressional plane waves or shocks, generating a pair of FACs. This polarization is not related to the separation between the electrons and ions caused by their difference in mass, a separation which is inherent to compressional waves. The resultant double field-aligned current structure exists both with and without the contributions from curvature drift, which is questionable in terms of its contribution to vorticity change from the viewpoint of single-particle motion.

Yamauchi, M.↗
NASA NTRS2010

Particle Access and Charging Environments in the Lunar Wake

A plasma wake a region of low density, high temperature plasma forms on the far side of the Moon when solar wind, magnetosheath, and magnetotail plasma flows past the Moon [Manka, 1973; Ogilvie et al., 1996; Farrell et al., 1998; Halekas et al., 2005]. Ion populations in these flows typically have much smaller thermal velocity than bulk speed and are therefore excluded from the plasma wake while the large thermal electron velocity allows the lighter negatively charged particles to stream ahead of the ions into the wake. Charge separation due to electrons streaming ahead of the ions into the wake from the wake boundary establishes an ambipolar electric field which impedes the motion of electron flow and accelerates ions into the wake [Ogilvie et al., 1996; Farrell et al., 1997]. We have conducted a theoretical study of acceleration (and deceleration) of charged particles in lunar plasma environments, which investigated the mechanisms responsible for allowing solar wind entry into the lunar wake, and for producing energetic particle distributions observed within the lunar wake. To this end, the investigation utilized a macroscale 3D hybrid particle-in-cell numerical model of the interaction of the Moon with external plasma environments to compute electric fields in the lunar environment for a variety of external plasma conditions and interplanetary magnetic field orientations. Ion dynamics were attained from the hybrid code while electron dynamics were determined by considering electron test particle trajectories through the fields established in the hybrid code. Results from the code will be presented to evaluate charging environments within the lunar wake.

Parker, Linda↗
NASA NTRS2014

A New Cell-Centered Implicit Numerical Scheme for Ions in the 2-D Axisymmetric Code Hall2de

We present a new algorithm in the Hall2De code to simulate the ion hydrodynamics in the acceleration channel and near plume regions of Hall-effect thrusters. This implementation constitutes an upgrade of the capabilities built in the Hall2De code. The equations of mass conservation and momentum for unmagnetized ions are solved using a conservative, finite-volume, cell-centered scheme on a magnetic-field-aligned grid. Major computational savings are achieved by making use of an implicit predictor/multi-corrector algorithm for time evolution. Inaccuracies in the prediction of the motion of low-energy ions in the near plume in hydrodynamics approaches are addressed by implementing a multi-fluid algorithm that tracks ions of different energies separately. A wide range of comparisons with measurements are performed to validate the new ion algorithms. Several numerical experiments with the location and value of the anomalous collision frequency are also presented. Differences in the plasma properties in the near-plume between the single fluid and multi-fluid approaches are discussed. We complete our validation by comparing predicted erosion rates at the channel walls of the thruster with measurements. Erosion rates predicted by the plasma properties obtained from simulations replicate accurately measured rates of erosion within the uncertainty range of the sputtering models employed.

electric propulsion↗
NASA NTRS1995

Solar Particle Induced Upsets in the TDRS-1 Attitude Control System RAM During the October 1989 Solar Particle Events

The three large solar particle events, beginning on October 19, 1989 and lasting approximately six days, were characterized by high fluences of solar protons and heavy ions at 1 AU. During these events, an abnormally large number of upsets (243) were observed in the random access memory of the attitude control system (ACS) control processing electronics (CPE) on-board the geosynchronous TDRS-1 (Telemetry and Data Relay Satellite). The RAM unit affected was composed of eight Fairchild 93L422 memory chips. The Galileo spacecraft, launched on October 18, 1989 (one day prior to the solar particle events) observed the fluxes of heavy ions experienced by TDRS-1. Two solid-state detector telescopes on-board Galileo, designed to measure heavy ion species and energy, were turned on during time periods within each of the three separate events. The heavy ion data have been modeled and the time history of the events reconstructed to estimate heavy ion fluences. These fluences were converted to effective LET spectra after transport through the estimated shielding distribution around the TDRS-1 ACS system. The number of single event upsets (SEU) expected was calculated by integrating the measured cross section for the Fairchild 93L422 memory chip with average effective LET spectrum. The expected number of heavy ion induced SEU's calculated was 176. GOES-7 proton data, observed during the solar particle events, were used to estimate the number of proton-induced SEU's by integrating the proton fluence spectrum incident on the memory chips, with the two-parameter Bendel cross section for proton SEU'S. The proton fluence spectrum at the device level was gotten by transporting the protons through the estimated shielding distribution. The number of calculated proton-induced SEU's was 72, yielding a total of 248 predicted SEU'S, very dose to the 243 observed SEU'S. These calculations uniquely demonstrate the roles that solar heavy ions and protons played in the production of SEU's during the October 1989 solar particle events.

Croley, D. R.↗
NASA NTRS2009

A Review of State-of-the-Art Separator Materials for Advanced Lithium-Based Batteries for Future Aerospace Missions

As NASA embarks on a renewed human presence in space, safe, human-rated, electrical energy storage and power generation technologies, which will be capable of demonstrating reliable performance in a variety of unique mission environments, will be required. To address the future performance and safety requirements for the energy storage technologies that will enhance and enable future NASA Constellation Program elements and other future aerospace missions, advanced rechargeable, lithium-ion battery technology development is being pursued with an emphasis on addressing performance technology gaps between state-of-the-art capabilities and critical future mission requirements. The material attributes and related performance of a lithium-ion cell's internal separator component are critical for achieving overall optimal performance, safety and reliability. This review provides an overview of the general types, material properties and the performance and safety characteristics of current separator materials employed in lithium-ion batteries, such as those materials that are being assessed and developed for future aerospace missions.

Bladwin, Richard S.↗
NASA NTRS1978

Inference of the ring current ion composition by means of charge exchange decay

The analysis of the measured ion fluxes during the several day storm recovery period and the assumption that beside hydrogen other ions were present and that the decays were exponential in nature, it was possible to establish three separate lifetimes for the ions. These fitted decay lifetimes are in excellent agreement with the expected charge exchange decay lifetimes for H(+), O(+), and He(+) in the energy and L-value range of the data. This inference technique, thus, establishes the presence of measurable and appreciable quantities of oxygen and helium ions as well as protons in the storm-time ring current. Indications that He(+) may also be present under these same conditions were found.

Smith, P. H.↗
NASA NTRS2010

Battery Separator Characterization and Evaluation Procedures for NASA's Advanced Lithium-Ion Batteries

To address the future performance and safety requirements for the electrical energy storage technologies that will enhance and enable future NASA manned aerospace missions, advanced rechargeable, lithium-ion battery technology development is being pursued within the scope of the NASA Exploration Technology Development Program s (ETDP's) Energy Storage Project. A critical cell-level component of a lithium-ion battery which significantly impacts both overall electrochemical performance and safety is the porous separator that is sandwiched between the two active cell electrodes. To support the selection of the optimal cell separator material(s) for the advanced battery technology and chemistries under development, laboratory characterization and screening procedures were established to assess and compare separator material-level attributes and associated separator performance characteristics.

Baldwin, Richard S.↗
NASA NTRS1989

ARCS 3 ionospheric artificial argon ion beam injections - Waves near the heavy ion gyrofrequencies

Low-frequency electric field data below the proton gyrofrequency are presented for the duration of the argon ion beam experiment conducted as part of the Argon Release for Controlled Studies (ARCS) program. An argon ion beam was injected from the subpayload antiparallel or perpendicular to the magnetic field at altitudes from 250 to 405 km. During the injections, the wave spectra were broadband near the subpayload and narrow-band near heavy ion gyrofrequencies at perpendicular separation distances between 42 and 254 m. It is suggested that the narrow-band waves are associated with both the perpendicular argon ion beam and an unexpected flux of low-energy ions which peaked in energy near 15 eV and pitch angle near 90 deg with respect to the magnetic field.

Erlandson, R. E.↗
NASA NTRS1975

Search for solid conductors of Na/+/ and K/+/ ions - Five new conductors

Five new conductors of positive Na and K ions, for use as separators in high energy secondary batteries, have been discovered. They include: (1) the pyrochlores NaTaWO6 and NaTa2O5F; (2) the bcc form of NaSbO3; and (3) the niobates 2Na2O-3Nb2O5 and 2K2O-3Nb2O5, with the alkali ions probably in open layers of the completely determined structure. On the basis of approximately 40 structure types, generalizations have been made regarding the relation between structure and ionic transport.

Singer, J.↗
NASA NTRS1990

Temperatures of individual ion species and heating due to charge exchange in the ionosphere of Venus

The coupled electron and multispecies ion energy equations were solved for daytime conditions in the Venus ionosphere. The heating rates due to charge exchange between hot oxygen atoms and thermal oxygen ions were calculated and incorporated into the energy equations. The combination of the traditional EUV heating and this hot oxygen energy source leads to calculated electron and individual ion temperatures significantly lower than the measured values during solar cycle maximum conditions. Calculations were also carried out for solar cycle minimum conditions, which led to considerably lower temperatures; no data are available which would allow direct comparisons of these results with measurements. In order to obtain calculated temperature values consistent with the observed ones, for solar cycle maximum conditions, topside heat inflows into the ion and electron gases have to be introduced or the thermal conductivity must be reduced by considering the effect of steady and fluctuating magnetic fields, as was done in previous studies. The addition of hot oxygen heating leads to minor increases in the calculated ion temperatures except for the case of reduced thermal conductivities. Separate temperatures were calculated for each ion species for a number of different conditions and in general the differences were found to be relatively small.

Kim, Jhoon↗
NASA NTRS1994

Voyager observations of O(+6) and other minor ions in the solar wind

The plasma science (PLS) experiments on the Voyager 1 and 2 spacecraft began making measurements of the solar wind shortly after the two launches in the fall of 1977. In reviewing the data obtained prior to the Jupiter encounters in 1979, we have found that the large dynamic range of the PLS instrument generally allows a clean separation of signatures of minor ions (about 2.5% of the time) during a single instrument scan in energy per charge. The minor ions, most notably O(+6), are well separated from the protons and alpha particles during times when the solar wind Mach number (ratio of streaming speed to thermal speed) is greater than approximately 15. During the Earth to Jupiter cruise we find that the average ratio of alpha particle number density to that of oxygen is 66 +/- 7 (Voyager 1) and 71 +/- 17 (Voyager 2). These values are consistent with the value 75 +/- 20 inferred from the Ion Composition Instrument on ISEE 3 during the period spanning 1978 and 1982. We have inferred an average coronal temperature of (1.7 +/- 0.1) x 10(exp 6) K based on the ratio of O(+7) to O(+6) number densities. Our observations cover a period of increasing solar activity. During this time we have found that the alpha particle to proton number density ratio is increasing with the solar cycle, the oxygen to proton ratio increases, and the alpha particle to oxygen ratio remains relatively constant in time.

Villanueva, Louis↗
NASA NTRS2011

24/7 Solar Minimum Polar Cap and Auroral Ion Temperature Observations

During the International Polar Year (IPY) two Incoherent Scatter Radars (ISRs) achieved close to 24/7 continuous observations. This presentation describes their data sets and specifically how they can provide the International Reference Ionosphere (IRI) a fiduciary E- and F-region ionosphere description for solar minimum conditions in both the auroral and polar cap regions. The ionospheric description being electron density, ion temperature and electron temperature profiles from as low as 90 km extending to several scale heights above the F-layer peak. The auroral location is Poker Flat in Alaska at 65.1 N latitude, 212.5 E longitude where the NSF s new Poker Flat Incoherent Scatter Radar (PFISR) is located. This location during solar minimum conditions is in the auroral region for most of the day but is at midlatitudes, equator ward of the cusp, for about 4-8 h per day dependent upon geomagnetic activity. In contrast the polar location is Svalbard, at 78.2 N latitude, 16.0 E longitude where the EISCAT Svalbard Radar (ESR) is located. For most of the day the ESR is in the Northern Polar Cap with a noon sector passage often through the dayside cusp. Of unique relevance to IRI is that these extended observations have enabled the ionospheric morphology to be distinguished between quiet and disturbed geomagnetic conditions. During the IPY year, 1 March 2007 - 29 February 2008, about 50 solar wind Corotating Interaction Regions (CIRs) impacted geospace. Each CIR has a two to five day geomagnetic disturbance that is observed in the ESR and PFISR observations. Hence, this data set also enables the quiet-background ionospheric climatology to be established as a function of season and local time. These two separate climatologies for the ion temperature at an altitude of 300 km are presented and compared with IRI ion temperatures. The IRI ion temperatures are about 200-300 K hotter than the observed values. However, the MSIS neutral temperature at 300 km compares favorably with the quiet-background in temperature, both in magnitude and climatology.

Sojka, Jan J.↗