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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 1,117 records · Page 62
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NASA NTRS1975

Effects of convection electric field on the distribution of ring current type protons

The topology of the boundaries of penetration (or, inversely, the boundaries of the forbidden regions) of 90-deg pitch-angle equatorial protons with energies less than 100 keV are explored for an equatorial convection E-field which is directed in general from dawn to dusk. Due to the dependence of drift path on energy (or magnetic moment), complex structural features are expected in the proton energy spectra detected by satellites since the penetration distance of a proton is not a monotonically increasing or decreasing function of energy. During a storm when the convection E is enhanced, model calculations predict elongations of the forbidden regions analogous to tail extensions of the plasmasphere. Following a reduction in the convection field, spiral-structured forbidden regions can occur. Structural features inherent to large-scale convection field changes may be seen in the nose-like proton spectrograms observed near dusk by instrumentation on Explorer 45. These nose events are modelled by using an electric field model developed originally by Volland (1973). The strength of the field is related to the Kp index through night-time equatorial plasmapause measurements.

Grebowsky, J. M.↗
NASA NTRS1975

Relative abundance of proton to helium nuclei in solar cosmic ray events

A statistical study of the relative abundance of proton to alpha particles at equal energy per nucleon has been carried out on the basis of some hundred solar particle events in the energy range 6-20 MeV/nuc. A small qualitative effect of the coronal propagation has been found for events associated with solar flares away from the observer 'preferred connection region' (20-80 deg W from the central meridian). The variation of the relative abundance of the proton to alpha particle at ejection is analyzed using events for which the coronal transport is minimum. It is found that micro events characterized by small proton intensity, little or no scattering in interplanetary medium and little or no trapping in the corona has an abundance of He-4 of 5-30% relative to proton. Those events frequently display a very high He-3 abundance from 30 to 150% relatively to He-4. For larger particle events, the alpha abundance decreases following a relation which is not valid for flare-associated events that accelerate particles to relativistic energies.

Van Hollebeke, M. A. I.↗
NASA NTRS1975

Anisotropy measurements of nearly 50 KeV solar protons

The Energetic Particles Experiment on IMP-7 measures the angular distribution of 50-200 keV solar protons in 16 sectors. The velocity of 50 keV protons may be less than 5 times that of the solar wind. A generalized nonlinear Compton-Getting point transformation into the co-moving frame that contains no assumptions as to the angular distribution of either the spectrum or intensity is presented. Nearly 50 keV proton data in the spacecraft frame exhibit an anisotropy ratio that is large (not less than 5) and radial throughout the October 29, 1972 event lasting more than 9 days at this energy. This anisotropy argues against impulsive injection and diffusive decay in the inner solar system. Application of the transformation to the data reveals a long lasting residual anisotropy in the co-moving frame with protons streaming from the sun. Differences between the co-moving frame and solar wind frame velocities suggest residual electric fields upstream from the bow shock.

Gold, R. E.↗
NASA NTRS1976

Proton magnetic relaxation and internal rotations in tetramethylammonium cadmium chloride

Nuclear magnetic resonance (NMR) and relaxation studies of the proton spin-lattice relaxation time (PSLRT) and proton second moment (PSM) are reported. Tetramethylammonium cadmium chloride (TMCC) was selected as a diamagnetic member of the isomorphic series, and hence proton data relate directly to the motion of the tetramethylammonium ion in the absence of paramagnetic ions. In the model adopted, the correlation time for hindered motion of one of the methyl groups differs from that of the other three groups in the low-temperature phase below 104 K. PSLRT and PSM values agree closely with experimental data with this model. Crystallographic phase transitions in TMCC occur at 104 K and 119 K according to the PSLRT measurements. Dipolar interactions between adjacent protons account for the PSLR rates below 104 K.

Tsang, T.↗
NASA NTRS1975

Proton transfer reactions from H3/+/ ions to N2, O2, and CO molecules

The rate constants for proton transfer from H3(+) ions to N2, O2, and CO have been measured as function of hydrogen-buffer-gas partial pressure. The rate constant for proton transfer from H3(+) to N2 shows a very large pressure dependence, increasing from 1.0 by 10 to the -9th power cu cm/s at low H2 partial pressures to 1.7 by 10 to the -9th power cu cm/s at high H2 partial pressures. The rate constants for proton transfer from H3(+) to O2 and CO are constant with partial pressure of H2. The roles of excess vibrational energy in H3(+) ions and of equilibrium between forward and back reactions are discussed. Back reaction is observed only for the reaction of H3(+) ions with O2, and an equilibrium constant of 2.0 (plus or minus 0.4) at 298 K has been determined. From these data, the proton affinity of O2 is deduced to be 0.47 (plus or minus 0.11) kcal/mole higher than that of H2.

Kim, J. K.↗
NASA NTRS1976

Suprathermal protons in the interplanetary solar wind

Using the Mariner 5 solar wind plasma and magnetic field data, we present observations of field-aligned suprathermal proton velocity distributions having pronounced high-energy shoulders. These observations, similar to the interpenetrating stream observations of Feldman et al. (1974), are clear evidence that such proton distributions are interplanetary rather than bow shock associated phenomena. Large Alfven speed is found to be a requirement for the occurrence of suprathermal proton distribution; further, we find the proportion of particles in the shoulder to be limited by the magnitude of the Alfven speed. It is suggested that this last result could indicate that the proton thermal anisotropy is limited at times by wave-particle interactions

Goodrich, C. C.↗
NASA NTRS1976

The inconsistency between proton charge exchange and the observed ring current decay

The equatorial pitch-angle distributions of ring-current ions observed during a storm recovery phase at L values between 3 and 4 are compared with the pitch-angle distributions predicted by proton charge exchange with neutral hydrogen. Large disagreements are found, and three alternative explanations are explored. (1) A strong proton source acts to mask the effects of charge exchange. It is believed that the required strong continual source with a unique pitch-angle and energy dependence is unrealistic at these low L values. (2) Presently accepted neutral hydrogen density models have densities well over an order of magnitude too large for a storm recovery phase. No evidence is known to support the required large errors in the densities. (3) The ring current at particle energies not exceeding 50 keV was dominated by some ion species other than protons during the storm recovery phase. Such ions must have much longer lifetimes for charge exchange with hydrogen than do protons. This alternative is strongly favored, with He(+) being an attractive candidate.

Lyons, L. R.↗
NASA NTRS1976

Explorer 45 observations of the proton ring current

Explorer 45 satellite data on the stormtime proton ring current are reported and analyzed. Storm-associated variations of equatorially mirroring protons, interactions between the ring current and the plasmapause, and storm recovery phase behavior are discussed. Pitch-angle distributions are plotted as a function of proton energy and radial distance, the structure implying domination of pitch-angle diffusion of ring-current protons in the plasmapause region by resonant interactions with ion cyclotron waves during storm recovery. The anisotropic precipitation in the plasmapause region and the more poleward isotropic precipitation observed at low altitudes outside the plasmapause are compared and distinguished.

Lyons, L. R.↗
NASA NTRS1977

Acceleration of protons at 32 Jovian radii in the outer magnetosphere of jupiter

During the inbound pass of Pioneer 10, a rapid ten-fold increase of the 0.2 to MeV proton flux was observed at 32 Jovian radii (R sub J). The total event lasted for 30 minutes and was made up of a number of superimposed individual events. At the time, the spacecraft was in the outer magnetosphere about 7 R sub J below the magnetic equator. Before and after the event, the proton flux was characteristic of the low flux level normally encountered between crossings of the magnetic equator. Flux changes at different energies were coherent within 1 minute; a time comparable to the time resolution of the data. The angular distributions were highly anisotropic with protons streaming towards Jupiter. A field-aligned dumbbell distribution was observed initially, and a pancake distribution just before the flux decayed to its pre-event value. The alpha particle flux changed as rapidly as the proton flux but peaked at different times. The energetic electron flux behaved differently; it increased gradually throughout the period.

Schardt, A. W.↗
NASA NTRS1977

On the high energy proton spectrum measurements

Reasons are considered for the steepening of the cosmic-ray proton spectrum above 1000 GeV and the 20% increase in inelastic cross sections of protons on carbon and polyethylene nuclei between 20 and 600 GeV observed in the Pronton 1, 2, and 3 satellite experiments. It is shown that these unexpected observations can arise as consequences of energy-dependent albedo (backscatter) from the calorimeter used in the experiments. The experimental apparatus employed is described along with an experimental setup for studying the albedo from the calorimeter, and experimental results are presented concerning the magnitude and energy variation of the albedo. The effects this albedo could have on the proton spectrum and cross-section measurements of the Proton experiments are estimated. The origin and nature of the albedo particles are briefly investigated.

Ellsworth, R. W.↗
NASA NTRS1978

High-energy proton radiation damage of high-purity germanium detectors

Quantitative studies of radiation damage in high-purity germanium gamma-ray detectors due to high-energy charged particles have been carried out; two 1.0 cm thick planar detectors were irradiated by 6 GeV/c protons. Under proton bombardment, degradation in the energy resolution was found to begin below 7 x 10 to the 7th protons/sq cm and increased proportionately in both detectors until the experiment was terminated at a total flux of 5.7 x 10 to the 8th protons/sq cm, equivalent to about a six year exposure to cosmic-ray protons in space. At the end of the irradiation, the FWHM resolution measured at 1332 keV stood at 8.5 and 13.6 keV, with both detectors of only marginal utility as a spectrometer due to the severe tailing caused by charge trapping. Annealing these detectors after proton damage was found to be much easier than after neutron damage.

Pehl, R. H.↗
NASA NTRS1978

Prompt solar proton events and coronal mass ejections

Data from the HAO white-light coronagraph and the X-ray telescope on Skylab have been used to investigate the coronal manifestations of 18 prompt solar proton events observed on the IMP 7 spacecraft during the Skylab period. Evidence is found that a mass-ejection event is a necessary condition for the occurrence of a prompt proton event. Mass-ejection events can be observed directly in the white-light coronagraph when they occur near the limb and inferred from the presence of a long-decay X-ray event when they occur on the disk. It is suggested that: (1) the occurrence of mass-ejection events facilitates the escape of protons - whether accelerated at low or high altitudes - to the interplanetary medium; and (2) there may exist a proton acceleration region above or around the outward moving ejecta far above the flare site.

Kahler, S. W.↗
NASA NTRS1978

Characteristics of sunward flowing proton and alpha particle fluxes of moderate intensity

The diffusive streaming of low-energy protons has been found to be predominately toward the sun during periods between prompt solar particle events. This occurs for essentially all solar wind velocities and proton intensities. The average radial component of this anisotropy (14%) and its dependence on the solar wind velocity agree with values found by a steady-state propagation model. The average radial component (16%) of the diffusive flow of low-energy alpha particles is similar to that observed for protons, suggesting a common origin. The sunward diffusion of alpha particles and protons indicates that these slightly enhanced fluxes contain a positive radial gradient. The direction of the diffusive anisotropy is a function of the magnetic field direction.

Marshall, F. E.↗
NASA NTRS1979

A query into the source of proton emission from solar flares, report 2

Seven solar flares that were followed by major proton events were examined to determine the diverse and common properties of major flares. The most probable site of primary proton acceleration is cospatial with the site and instant of formation of coronal loops. Because loop formation occurs through the entire duration of major solar flares over significantly large areas of active centers, it is proposed that proton injection occurs from a relatively large volume of space in the corona of active centers and is continuous throughout, and possibly even after, the visible duration of the related chromospheric flare. The flare veil is hypothesized to occur as a result of proton charge exchange taking place in the white-light transient. The Kopp and Pneuman model of loop formation by magnetic reconnection is suggested as an adequate and satisfactory model for all major flares with the provision that the beginning of rapid magnetic field reconnection is coincident with flare start.

Martin, S. F.↗
NASA NTRS1978

Simultaneous measurements of energetic protons and electrons in the distant magnetosheath, magnetotail, and upstream in the solar wind

The paper investigates the presence of energetic protons and electrons in the magnetopause/magnetosheath region of the tail as well as upstream from the bow shock in the solar wind, estimates the energy densities of protons and electrons, and assesses the relationship between the energies associated with these particles and the dayside reconnection region. The study is based on measurements in experiments on the IMP 7 and 8 spacecraft. It is shown that the energetic protons and electrons are present not only in the distant magnetosheath but also in the upstream solar wind and inside the magnetosphere. These protons carry much more energy (x50) than the electrons, and most likely originate inside the magnetosphere. Thus there appears to be little connection between the presence of these energetic particles in the distant magnetosheath region and the dayside reconnection region.

Krimigis, S. M.↗
NASA NTRS1979

Anisotropies in the fluxes of Pioneer 10 protons

One-hour-averaged fluxes of 1.8- to 2.15-MeV protons observed by the LET2 detector on Pioneer 10 on the inbound trajectory showed anisotropies attributable to corotation of Jupiter's magnetodisc only when Pioneer was near the dipole equator. Most of the time the anisotropy greatly exceeded the value expected from corotation. Gradients in the distribution function can be used to account for this excess anisotropy, but the amount of gradient required is unacceptably large by 1-2 orders of magnitude. If they were taken as real, these gradients would predict almost complete disappearance of these protons from Jupiter's magnetosphere in a matter of hours. The remedy is to introduce into the model of the distribution function proton flow along field lines away from the equator into both the southern and the northern hemisphere. The parallel flux at the southernmost latitudes reached by Pioneer can reach 25% of the product of proton density and velocity, i.e., 25% of the maximum possible.

Northrop, T. G.↗
NASA NTRS1978

An estimation of the primary proton spectrum between 10 to the 12th and 10 to the 14th eV

Based on measurements of unaccompanied charged hadron flux from 10 to the 11th to 10 to the 14th eV at mountain altitudes, the primary proton flux is estimated using recently determined proton-proton total cross sections from new measurements of the real part of the forward scattering amplitude at ISR, and Glauber theory to calculate proton-air inelastic cross section. The derived spectrum agrees well with extrapolation of the direct measurements below 2 times 10 to the 12th eV without change of slope.

Gaisser, T. K.↗
NASA NTRS1980

Instability of equatorial protons in Jupiter's mid-magnetosphere

Two different models for the distribution function are fit to the Jovian protons seen by Pioneer 10 inbound. The models reproduce the observed energy and angular distributions. These models are then used to assess the collisionless mirror instability. Because of the pancake proton angular distributions in the equatorial ring current region, the ring current particle population appears to be mirror unstable at times, with instability growth rates of about 10 min. Such a time is consistent with observed proton flux autocorrelation times. An instability such as this (there are other candidates) may be responsible for the previously established proton flux flowing parallel to the magnetic field away from the equatorial region.

Northrop, T. G.↗