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Results for “Charged Particle”

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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

NASCAP modelling of high-voltage power system interactions with space charged-particle environments

A simple space power system operating in geosynchronous orbit was analyzed. This system consisted of two solar array wings and a central body. Each solar array wing was considered to be divided into three regions operating at 2000 volts. The center body was considered to be an electrical ground with the array voltages both positive and negative relative to ground. The system was analyzed for both a normal environment and a moderate geomagnetic substorm environment. Initial results indicate a high probability of arcing at the interconnects on the negative operating voltage wing. The dielectric strength of the substrate may be exceeded giving rise to breakdown in the bulk of the material. The geomagnetic substorm did not seem to increase the electrical gradients at the interconnects on the negative operating voltage wing but did increase the gradients on the positive operating voltage wing which could result in increased coupling current losses.

Stevens, N. J.↗
NASA NTRS1979

Mapping of electrical potential distribution with charged particle beams

Potentials were measured using a beam of soft X-rays in air at 2 x 10 to the -5 power Torr. Ions were detected by a continuous-dynode electron multiplier after they passed through a retarding field. Ultimate resolution depends upon the diameter of the X-ray beam which was 3 mm. When the fields in the region of interest were such to disperse the ions, only a small fraction were detected and the method of measurement was not very reliable. Yet reasonable data could be collected if the ions traveled in parallel paths toward the detector. Development should concentrate on increasing the aperture of the detector from the pinhole which was used to something measured in centimeters. Also increasing the strength of the source would provide a stronger signal and more reliable data. Measurements were made at an estimated ion current to 10 to the -15 power A from a 10 cm length of the X-ray beam, this current being several orders of magnitude below what would have a perturbing effect on the region to be measured. Consequently, the source strength can be increased and prospects for this method of measurement are good.

Robinson, J. W.↗
NASA NTRS1980

Coordinated ionospheric and magnetospheric observations from the ISIS 2 satellite by the ISIS 2 experimenters. Volume 3: High-latitude charged particle, magnetic field and ionospheric plasma observations during northern summer

A list of ISIS 2 experiments and a description of the satellite are presented. Instrumentation of the satellite included an auroral scanning photometer, a red line photometer, a swept frequency sounder, an ion mass spectrometer, and triaxial fluxgate magnetometer. Data format descriptions are provided. Included with the geophysical data set is a list of all passes.

Source record↗
NASA NTRS1981

Observations of interplanetary energetic charged particles from gamma-ray line solar flares

Observations of interplanetary energetic ions from the 7 June, 21 June and 1 July 1980 gamma ray line solar flares are presented. The observations are from the Max-Planck-Institut/University of Maryland Ultra Low Energy Wide Angle Telescope aboard the ISEE-3 spacecraft. Both June flares produced relatively low intensity proton events at earth with peak intensities at 10-20 MeV approximately 5 x .01 protons square cm sec sr MeV)-1. Neither flare showed evidence of being enriched in either 3He or Fe at approximately 1 MeV/nucleon. The 1 July flare produced no observable ion or electron enhancements.

Pesses, M. E.↗
NASA NTRS1981

Analytical description of charged particles transport along arbitrary guiding-field configurations

A new description of focused transport was developed which is valid for arbitrary spatial dependences of both the scattering mean free path and the focusing length. In particular, it describes the supercoherent transition from the coherent modes that occurs when focusing is strong compared to scattering to the diffusive mode that occurs when focusing is weak. Because it specifies the pitch angle distribution in terms of relatively simple functions, the new formulation facilitates not only the detailed interpretation of solar particle events, but also the qualitative understanding of focused transport. In the steady state, it predicts that the angular distribution consists of a highly collimated 'strahl' which is superimposed on an anisotropic 'halo'. This picture provides new insight into observed configurations of steady-state particle fluxes.

Earl, J. A.↗
NASA NTRS1980

Acceleration of energetic charged particles by interplanetary and interstellar shock waves

Pioneer 11 observations of energetic proton acceleration in interplanetary shocks are in good agreement with the predictions of the Vector-V x Vector-B electric field model of shock acceleration. The Vector-V x Vector-B model predicts that relativistic particles are accelerated by a factor of 2-15 in kinetic energy during a single encounter with a quasi-perpendicular (not less than 70 deg) supernova shock wave, and that the post-encounter pitch angle distributions are very anisotropic.

Pesses, M. E.↗
NASA NTRS1980

Charged particle anisotropics in Saturn's magnetosphere

The paper deals with observations of anisotropies and pitch angle distributions for 0.5 to 1.8 MeV protons and 7 to 17 MeV electrons in Saturn's magnetosphere. In the outer magnetosphere (L = 6), there is clear evidence for corotation of the proton flux. The pitch-angle distribution shows maximum flux perpendicular to the magnetic field ('pancake' distribution). Observed changes in the amplitude and shape of the pitch angle distributions suggest the existence of substantial temporal variations in the outer magnetosphere. From L = 6 to L = 4, the proton intensity decreased by more than two orders of magnitude, while the pitch angle distribution shifted to a 'dumbbell' form (maximum flux parallel to magnetic field).

Bastian, T. S.↗
NASA NTRS1980

Charged particle diffusion and acceleration in Saturn's radiation belts

In the present paper, an attempt is made to determine, from the observed intensity profiles for protons and electrons in the region of L smaller than 4, whether population of Saturn's innermost trapped radiation zones from an external source is possible. It is found that if diffusion proceeds in an episodic rather than a steady-state manner (long periods of quiescence interrupted by brief periods of rapid diffusion), the basic features of the observed phase space density profiles are qualitatively reproduced for both the trapped protons and electrons.

Mckibben, R. B.↗
NASA NTRS1981

Energetic charged particles in Saturn's magnetosphere - Voyager 1 results

Voyager 1 provided the first look at Saturn's magnetotail and magnetosphere during relatively quiet interplanetary conditions. This report discusses the energetic particle populations of the outer magnetosphere of Saturn and absorption features associated with Titan and Rhea, and compares these observations with Pioneer 11 data of a year earlier. The trapped proton fluxes had soft spectra, represented by power laws in kinetic energy with an exponent of 7 in the outer magnetosphere and 9 in the magnetotail. Structure associated with the magnetotail was observed as close as 10 Saturn radii on the outbound trajectory. The proton and electron fluxes in the outer magnetosphere and in the magnetotail were variable and appeared to respond to changes in interplanetary conditions. Protons with energies greater than or approximately equal to 2 MeV had free access to the magnetosphere from interplanetary space and were not stably trapped outside about 7.5 Saturn radii.

Vogt, R. E.↗
NASA NTRS1981

Monte Carlo simulation of charged particles upstream of the earth's bow shock

A simple model of the earth's bow shock is presented and compared with ISEE-1 observations of diffuse ions upstream of the shock. Ion behavior is modeled in a test particle simulation using Monte Carlo techniques for a plane parallel shock at which cold solar wind ions are heated sufficiently to allow diffusion back upstream. Fitting of the model to the observations indicates that the diffusion coefficient must increase faster than linearly with velocity, and provides an upper limit to the acceleration efficiency defined as the proportion of incoming solar wind ions accelerated and observed upstream. Results suggest that astrophysical shocks are capable of accelerating ions directly from the thermal plasma without the need for a distinct preenergizing injection stage.

Ellison, D. C.↗
NASA NTRS1981

Design of prototype charged particle fog dispersal unit

The unit was designed to be easily modified so that certain features that influence the output current and particle size distribution could be examined. An experimental program was designed to measure the performance of the unit. The program described includes measurements in a fog chamber and in the field. Features of the nozzle and estimated nozzle characteristics are presented.

Collins, F. G.↗
NASA NTRS1981

Phenomena induced by charged particle beams

The injection of energetic particles along the Earth's magnetic field lines is a possible remote sensing method for measuring the electric fields parallel to the magnetic field with good time resolution over the entire magnetic field. Neutralization processes, return-current effects, dynamics of the beams, triggered instabilities, and waves must be investigated before the fundamental question about proper experimental conditions, such as energy, intensity and divergence of the beams, pitch-angle injection, ion species, proper probes and detectors and their location, and rendezvous conditions, can be resolved. An experiment designed to provide a better understanding of these special physical processes and to provide some answers to questions concerning beam injection techniques is described.

Beghin, C.↗
NASA NTRS1980

Late biological effects of heavy charged particles: Cataracts, vascular injury and life shortening in mice

Risks associated with extended habitation in a space environment, particularly hazards to space workers that might result from exposure to high energy heavy ion particles (HZE), were studied. Biological effects of HZE were investigated in mice to assess their potential adverse health hazards. The potential effects of HZE particles on the crystalline lens of the eye and the carcinogenic effects and blood vessel (vascular) damage from radiation were evaluated by a risk assessment. Animal experiments to evaluate dose response relationships for tumor induction/promotion and for vascular injury were introduced. Cataract productions and preliminary results on cacinogenic and vascular effects are presented for perspective.

Ainsworth, E. J.↗
NASA NTRS1981

Magnetic fields and charged particles around major planets and their satellites

It is noted that whereas Jupiter and Saturn have magnetospheres whose large-scale structure can be understood by analogy with earth, the ways in which the magnetospheres differ are of great interest. At earth, large-scale processes are dominated by convective flows of plasma driven by the solar wind. At Jupiter, centrifugal effects that are driven by planetary rotation are critical. Magnetic particle sources include not only the ionosphere and solar wind (as at earth) but also satellites and rings. The internal planetary magnetic moments controlling the scale of the magnetosphere differ by orders of magnitude between Jupiter and earth. It is pointed out that where the magnetic moments have been modeled from spacecraft data, the restricted spatial sampling has biased the results and limited confidence in details of the models. Voyager data suggest that Io may itself be magnetized and surrounded by an entirely unfamiliar type of magnetosphere.

Kivelson, M. G.↗
NASA NTRS1982

Adiabatic charged particle motion in rapidly rotating magnetospheres

Some aspects of adiabatic drift theory are investigated in the regime where the E x B drift velocity is comparable with or larger than the gyro velocity. Particles undergo five drifts in addition to the E x B gradient, and line curvature drifts have three more terms in the parallel equation of motion. The case of the rapidly rotating rigid magnetic field configuration is found to be an exception due to the corotating particle with a nearly periodic motion. The guiding center drift velocity and parallel differential equation of motion are obtained, and the drift velocity in the rotating frame is found to consist of the expected field gradient and line curvature drift, plus centrifugal and coriolis force induced drifts. It is shown that the second invariant is conserved in the rotating frame by the four drifts, so that a particle slowly drifts around on its drift shell and returns to its original field line. Thus, there is no long term energy change, and any energy change is periodic on the bounce and drift time scale.

Northrop, T. G.↗
NASA NTRS1981

Analytical description of charged particle transport along arbitrary guiding-field configurations

Focused particle transport is analyzed in terms of partial differential equations which are applicable to arbitrary spatial variations of the mean free path and the focusing length. A distribution function for transport is written in two forms of the Boltzmann equation and a coefficient of spatial diffusion is defined. Changes from a nearly coherent propagation of flare particles in regions of strong focusing near the sun to ordinary diffusion in the outer solar system are described as supercoherent transitions. A solution to the steady state problem is developed and results are presented for a monopolar guiding field configuration with isotropic diffusion gradually giving way to anisotropy in a region suggestive of a collimated beam of particles streaming away from its source.

Earl, J. A.↗