SEARCH · Search NASA

Results for “proton generation”

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.

SourceResearch connectionFrom yearThrough year

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

At least 235 records · Page 13

All sources NASA NTRS DOE OSTI

NASA NTRS1988

Transition region, corona, and solar wind in coronal holes - Some two-fluid models

A model is presented which treats the heating of the corona and the heating and acceleration of the solar wind as a single process, namely, the turbulent dissipation of solar-generated Alfven waves at the Kolmogorov rate. This model is similar to that described by Hollweg (1986), except that the electron temperature and the proton temperature are allowed to have different values. It is found that, similar to the findings of Hollweg, solutions which yield base pressures in the observed range lead to solar wind flows which are much too slow at 1 AU; a new feature is the appearance of proton temperature peak near 3-4 solar radii. Thus, this model seems to be also unsatisfactory. Several possible resolutions are discussed.

Hollweg, Joseph V.↗

NASA NTRS1997

Total Dose Testing of a CMOS Charged Particle Spectrometer

A first-generation CMOS Charged Particle Spectrometer chip [1] was designed at JPL for flight on the STRV-2 spacecraft. These devices will collect electron and proton spectra in low Earth orbit as part of an experiment to demonstrate Active Pixel Sensor (APS) technology in space. This paper presents the results of total dose testing on these chips and, where possible, attempts to extend the results to other Active Pixel Sensors.

CMOS↗

NASA NTRS1995

Use of Advanced Solar Cells for Commercial Communication Satellites

The current generation of communications satellites are located primarily in geosynchronous Earth orbit (GEO). Over the next decade, however, a new generation of communications satellites will be built and launched, designed to provide a world-wide interconnection of portable telephones. For this mission, the satellites must be positioned in lower polar and near-polar orbits. To provide complete coverage, large numbers of satellites will be required. Because the required number of satellites decreases as the orbital altitude is increased, fewer satellites would be required if the orbit chosen were raised from low to intermediate orbit. However, in intermediate orbits, satellites encounter significant radiation due to trapped electrons and protons. Radiation tolerant solar cells may be necessary to make such satellites feasible. We analyze the amount of radiation encountered in low and intermediate polar orbits at altitudes of interest to next-generation communication satellites, calculate the expected degradation for silicon, GaAs, and InP solar cells, and show that the lifetimes can be significantly increased by use of advanced solar cells.

Bailey, Sheila G.↗

NASA NTRS1979

Super-Alfvenic particle streaming in astrophysical settings

The pitch angle scattering of relativistic particles by self-generated hydromagnetic waves is discussed. It is shown that in a hot background plasma, because of the resonant damping of short wavelength waves by thermal protons, cosmic rays need not slow down to a mean streaming speed which is of order the Alfven speed. The effects of a high cosmic ray energy density upon the destabilized wave model are also discussed. Recent work indicates that when the cosmic ray energy density is on the order of or exceeds the energy density in the ambient magnetic field, the velocity of the amplified waves is significantly greater than the Alfven speed. These effects have important implications for recent cosmic ray acceleration models and are important for studies of particle propagation in many astrophysical plasmas.

Holman, G. D.↗

NASA NTRS1991

Monte Carlo Shower Counter Studies

Activities and accomplishments related to the Monte Carlo shower counter studies are summarized. A tape of the VMS version of the GEANT software was obtained and installed on the central computer at Gallaudet University. Due to difficulties encountered in updating this VMS version, a decision was made to switch to the UNIX version of the package. This version was installed and used to generate the set of data files currently accessed by various analysis programs. The GEANT software was used to write files of data for positron and proton showers. Showers were simulated for a detector consisting of 50 alternating layers of lead and scintillator. Each file consisted of 1000 events at each of the following energies: 0.1, 0.5, 2.0, 10, 44, and 200 GeV. Data analysis activities related to clustering, chi square, and likelihood analyses are summarized. Source code for the GEANT user subprograms and data analysis programs are provided along with example data plots.

Snyder, H. David↗

NASA NTRS1988

Simulation and non-linear stage of the electrostatic waves observed during the AMPTE lithium release in the solar wind

During the AMPTE lithium releases in the solar wind intense electrostatic waves with frequencies between a few tens of Hz to several kHz were observed outside the diamagnetic cavity. The results of linear Vlasov theory have suggested that these waves may be generated through two types of instabilities. One is the ion-ion instability associated with the relative drift between the lithium ions and the solar wind protons, and the other is the ion-acoustic instability due to the relative drift between the electrons and the ions. In order to look at the non-linear behavior of the wave-particle interactions, and discern the effect of waves on the particles, full particle electrostatic simulations have been performed, and the results are presented here. It is shown that the ion-ion instability whose phase velocity is oblique to the solar wind velocity can cause considerable anisotropic 'heating' of both the lithium ions and the solar wind protons.

Omidi, N.↗

NASA NTRS2019

Radiolysis of Macromolecular Organic Material in Mars-Relevant Mineral Matrices

The fate of organic material on Mars after deposition is crucial to interpreting the source of these molecules. Previous work has addressed how various organic compounds at millimeter depths in sediments respond to ultraviolet radiation. In contrast, this study addressed how high‐energy particle radiation (200‐MeV protons, simulating the effect of galactic cosmic rays and solar wind at depths of <4–5 cm) inﬂuences organic macromolecules in sediments. Speciﬁcally, we report the generation of organic‐acid radiolysis products after exposure to radiation doses equivalent to geological time scales (1–7 Myr). We found that formate and oxalate were produced from a variety of organic starting materials and mineral matrices. Unlike ultraviolet‐driven reactions that can invoke Fenton chemistry to produce organic acids, our work suggests that irradiation of semiconductor surfaces, such as TiO2 or possible clay minerals found on Mars, forms oxygen and hydroxyl radical species, which can break down macromolecules into organic acids. We also investigated the metastability of benzoate in multiple mineral matrices. Benzoate was added to samples prior to irradiation and persisted up to 500 kGys of exposure. Our ﬁndings suggest that organic acids are likely a major component of organic material buried at depth on Mars.

Fox, A. C.↗

NASA NTRS2023

Compressible Turbulence in the Near-Sun Solar Wind Parker Solar Probe's First Eight Perihelia

Many questions remain about the compressibility of solar wind turbulence with respect to its origins and properties. Low plasma beta (ratio of thermal to magnetic pressure) environments allow for the easier generation of compressible turbulence, enabling study of the relationship between density fluctuations and turbulent Mach number. Utilizing Parker Solar Probe plasma data, we examine the normalized proton density fluctuations as a function of turbulent Mach number M t conditioned on plasma beta and cross helicity. With consideration of statistical error in the parameters computed from in situ data, we find a general result consistent with both linear-wave theory and nearly incompressible turbulence in an inhomogeneous background field. We compare observational results conditioned on plasma beta and cross helicity with 3D magnetohydrodynamic simulations and observe rather significant similarities with respect to how those parameters affect the proportionality between density fluctuations and turbulent Mach number. This study further investigates the complexity of compressible turbulence as viewed by the density scaling relationship and may help better understand the compressible environment of the near-Sun solar wind.

Manuel Enrique Cuesta↗

NASA NTRS2012

Pickup Protons: Comparisons using the Three-Dimensional MHD HHMS-PI model and Ulysses SWICS Measurements

We report the first comparisons of pickup proton simulation results with in situ measurements of pickup protons obtained by the SWICS instrument on Ulysses. Simulations were run using the three dimensional (3D) time-dependent Hybrid Heliospheric Modeling System with Pickup Protons (HHMS-PI). HHMS-PI is an MHD solar wind model, expanded to include the basic physics of pickup protons from neutral hydrogen that drifts into the heliosphere from the local interstellar medium. We use the same model and input data developed by Detman et al. (2011) to now investigate the pickup protons. The simulated interval of 82 days in 2003 2004, includes both quiet solar wind (SW) and also the October November 2003 solar events (the Halloween 2003 solar storms). The HHMS-PI pickup proton simulations generally agree with the SWICS measurements and the HHMS-PI simulated solar wind generally agrees with SWOOPS (also on Ulysses) measurements. Many specific features in the observations are well represented by the model. We simulated twenty specific solar events associated with the Halloween 2003 storm. We give the specific values of the solar input parameters for the HHMS-PI simulations that provide the best combined agreement in the times of arrival of the solar-generated shocks at both ACE and Ulysses. We show graphical comparisons of simulated and observed parameters, and we give quantitative measures of the agreement of simulated with observed parameters. We suggest that some of the variations in the pickup proton density during the Halloween 2003 solar events may be attributed to depletion of the inflowing local interstellar medium (LISM) neutral hydrogen (H) caused by its increased conversion to pickup protons in the immediately preceding shock.

Intriligator, Devrie S.↗

NASA NTRS1974

Trapped particle and solar proton radiation prediction for ISEE (IME): Mother-daughter mission

The charged particle fluxes incident on spacecrafts in very eccentric orbits were investigated in support of the International Sun-Earth Explorer (International Magnetospheric Explorer) For this purpose, two flightpaths were considered having identical inclinations but different perigee altitudes (240 and 1364 kilometers, respectively). Apogee altitude was approximately the same for both cases (about 22 earth radii). For each of the two perigee altitudes investigated, two nominal trajectories were generated, having identical orbital configurations but with their major axes rotated by 180 deg in the plane of orbit, which resulted in placing the initial apogee into into opposite hemispheres. This was done in order to determine the corresponding variation in the vehicle-encountered particle intensities. Estimates of average energetic solar proton fluxes are given for a one year mission duration at selected integranlenergies ranging from E 10 to E 100 MeV. Results are summarized and discussed.

Stassinopoulos, E. G.↗

NASA NTRS1984

Magnetosonic waves adjacent to the plasma sheet in the distant magnetotail - ISEE-3

The presence of large-amplitude magnetosonic waves in the distant plasma sheet boundary layers is demonstrated, and their properties are discussed. The waves for almost all the events examined are right-hand circularly polarized, with the degree of polarization varying from 1.04 to 1.87, i.e., from circular to slightly elliptical. The waves are all propagating nearly along the magnetic field. Their periods vary from 3.7 seconds to as long as 35 seconds, with a median value of about 10 seconds, and are slightly larger than the proton gyroperiod in all but two cases. Most waves have a relatively large compressional component varying from 30 to 90 percent of the wave amplitude. Several possible generation mechanisms are discussed, along with the role that the waves may play in the heating and expansion of the plasma sheet.

Tsurutani, B. T.↗

NASA NTRS2005

Hybrid Power Management Program Evaluated Ultracapacitors for the Next Generation Launch Transportation Project

The NASA Glenn Research Center initiated baseline testing of ultracapacitors to obtain empirical data in determining the feasibility of using ultracapacitors for the Next Generation Launch Transportation (NGLT) Project. There are large transient loads associated with NGLT that require a very large primary energy source or an energy storage system. The primary power source used for this test was a proton-exchange-membrane (PEM) fuel cell. The energy storage system can consist of batteries, flywheels, or ultracapacitors. Ultracapacitors were used for these tests. NASA Glenn has a wealth of experience in ultracapacitor technology through the Hybrid Power Management (HPM) Program, which the Avionics, Power and Communications Branch of Glenn s Engineering Development Division initiated for the Technology Transfer and Partnership Office. HPM is the innovative integration of diverse, state-ofthe- art power devices in optimal configurations for space and terrestrial applications. The appropriate application and control of the various advanced power devices (such as ultracapacitors and fuel cells) significantly improves overall system performance and efficiency. HPM has extremely wide potential. Applications include power generation, transportation systems, biotechnology systems, and space power systems. HPM has the potential to significantly alleviate global energy concerns, improve the environment, and stimulate the economy.

Eichenberg, Dennis J.↗

NASA NTRS2005

Electric Power System Technology Options for Lunar Surface Missions

In 2004, the President announced a 'Vision for Space Exploration' that is bold and forward-thinking, yet practical and responsible. The vision explores answers to longstanding questions of importance to science and society and will develop revolutionary technologies and capabilities for the future, while maintaining good stewardship of taxpayer dollars. One crucial technology area enabling all space exploration is electric power systems. In this paper, the author evaluates surface power technology options in order to identify leading candidate technologies that will accomplish lunar design reference mission three (LDRM-3). LDRM-3 mission consists of multiple, 90-day missions to the lunar South Pole with 4-person crews starting in the year 2020. Top-level power requirements included a nominal 50 kW continuous habitat power over a 5-year lifetime with back-up or redundant emergency power provisions and a nominal 2-kW, 2-person unpressurized rover. To help direct NASA's technology investment strategy, this lunar surface power technology evaluation assessed many figures of merit including: current technology readiness levels (TRLs), potential to advance to TRL 6 by 2014, effectiveness of the technology to meet the mission requirements in the specified time, mass, stowed volume, deployed area, complexity, required special ground facilities, safety, reliability/redundancy, strength of industrial base, applicability to other LDRM-3 elements, extensibility to Mars missions, costs, and risks. For the 50-kW habitat module, dozens of nuclear, radioisotope and solar power technologies were down-selected to a nuclear fission heat source with Brayton, Stirling or thermoelectric power conversion options. Preferred energy storage technologies included lithium-ion battery and Proton Exchange Membrane (PEM) Regenerative Fuel Cells (RFC). Several AC and DC power management and distribution architectures and component technologies were defined consistent with the preferred habitat power generation technology option and the overall lunar surface mission. For rover power, more than 20 technology options were down-selected to radioisotope Stirling, liquid lithium-ion battery, PEM RFC, or primary fuel cell options. The author discusses various conclusions that can be drawn from the findings of this surface power technologies evaluation.

Kerslake, Thomas W.↗

NASA NTRS2004

New Gas Polarographic Hydrogen Sensor

Polarography is the measurement of the current that flows in solution as a function of an applied voltage. The actual form of the observed polarographic current depends upon the manner in which the voltage is applied and on the characteristics of the working electrode. The new gas polarographic H2 sensor shows a current level increment with concentration of the gaseous H2 similar to those relating to metal ions in liquid electrolytes in well-known polarography. This phenomenon is caused by the fact that the diffusion of the gaseous H2 through a gas diffusion hole built in the sensor is a rate-determining step in the gaseous-hydrogen sensing mechanism. The diffusion hole artificially limits the diffusion of the gaseous H2 toward the electrode located at the sensor cavity. This gas polarographic H2 sensor. is actually an electrochemical-pumping cell since the gaseous H2 is in fact pumped via the electrochemical driving force generated between the electrodes. Gaseous H2 enters the diffusion hole and reaches the first electrode (anode) located in the sensor cavity to be transformed into an H+ ions or protons; H+ ions pass through the electrolyte and reach the second electrode (cathode) to be reformed to gaseous H2. Gas polarographic 02 sensors are commercially available; a gas polarographic 02 sensor was used to prove the feasibility of building a new gas polarographic H2 sensor.

Dominguez, Jesus A.↗

NASA NTRS2006

H2 Detection via Polarography

Polarography is the measurement of the current that flows in solution as a function of an applied voltage. The actual form of the observed polarographic current depends upon the manner in which the voltage is applied and on the characteristics of the working electrode. The new gas polarographic H2 sensor shows a current level increment with concentration of the gaseous H2 similar to those relating to metal ions in liquid electrolytes in well-known polarography. This phenomenon is caused by the fact that the diffusion of the gaseous H2 through a gas diffusion hole built in the sensor is a rate-determining step in the gaseous-hydrogen sensing mechanism. The diffusion hole artificially limits the diffusion of the gaseous H2 toward the electrode located at the sensor cavity. This gas polarographic H2 sensor is actually an electrochemical-pumping cell since the gaseous H2 is in fact pumped via the electrochemical driving force generated between the electrodes. Gaseous H2 enters the diffusion hole and reaches the first electrode (anode) located in the sensor cavity to be transformed into an H ions or protons; H ions pass through the electrolyte and reach the second electrode (cathode) to be reformed to gaseous H2. Gas polarographic O2 sensors are commercially available; a gas polarographic O2 sensor was used to prove the feasibility of building a new gas polarographic H2 sensor.

Dominquez, Jesus↗

NASA NTRS1984

Constraints on continuous beam models of the jet in 3C 273

The one-sidedness, 'superluminal' motion, and detailed spectra observed for 3C 273 put significant constraints on continuous beam models for the source of the extended emission in 3C 273 A. The one-sidedness of the extended emission implies that the age of the radio-frequency cloud is probably about 3-5 Myr. The 'superluminal' motion observed with VLBI constrains the bulk Lorentz factor of the jet to be more than about 10. Finally, the observed X-ray emission from the jet provides a method for deciding the question of beam composition: for a given beam power, an electron-positron beam would produce a much higher (beamed) inverse-Compton X-ray flux off extended-jet optical photons than an electron-proton beam would, thus making the observed weak jet X-ray flux a strong indicator of a proton positive component to the jet. Remaining experimental uncertainties in the case of 3C 273 make it impossible to decide the question of beam composition at present, but the next generation of experiments may make this possible for 3C 273 and other 'superluminal' objects. The above arguments have the advantage of not depending on the details of the mechanism for producing the high-energy radio-cloud electrons.

Roberts, D.↗

NASA NTRS1991

Theory and simulation of cometary shocks

In this paper, recent kinetic simulation studies of cometary bow shocks are reviewed. Cometary shocks are formed due to solar wind mass loading by water group cometary ions. This process is kinetic in nature and varies as a function of the angle between the solar wind flow velocity and the interplanetary magnetic field, as do the properties of cometary shocks. For perpendicular and parallel orientations, quasi-steady shocks with dissipation scales on the order of proton inertial length form. At oblique orientations, no steady shocks are formed; instead, the transition from supersonic to subsonic flow takes place through multiple shocklets (steepened magnetosonic waves) which are generated by the pickup ions via the resonant electromagnetic ion beam instability. This new, time dependent model of cometary bow shocks is further investigated using a large scale kinetic simulation and is compared to the observations at Comet Giacobini-Zinner.

Omidi, N.↗

NASA NTRS1994

Theoretical studies of the solar atmosphere and interstellar pickup ions

Solar atmosphere research activities are summarized. Specific topics addressed include: (1) coronal mass ejections and related phenomena; (2) parametric instabilities of Alfven waves; (3) pickup ions in the solar wind; and (4) cosmic rays in the outer heliosphere. Also included is a list of publications covering the following topics: catastrophic evolution of a force-free flux rope; maximum energy release in flux-rope models of eruptive flares; sheet approximations in models of eruptive flares; material ejection, motions of loops and ribbons of two-ribbon flares; dispersion relations for parametric instabilities of parallel-propagating; parametric instabilities of parallel-propagating Alfven waves; beat, modulation, and decay instabilities of a circularly-polarized Alfven wave; effects of time-dependent photoionization on interstellar pickup helium; observation of waves generated by the solar wind pickup of interstellar hydrogen ions; ion thermalization and wave excitation downstream of the quasi-perpendicular bowshock; ion cyclotron instability and the inverse correlation between proton anisotrophy and proton beta; and effects of cosmic rays and interstellar gas on the dynamics of a wind.

Source record↗