Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Charging Experience”

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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Saturnian trapped radiation and its absorption by satellites and rings - The first results from Pioneer 11

Preliminary results from Pioneer 11 concerning the acceleration and trapping of charged particles in the magnetic field of Saturn are reported. The identification and measurement of the intensities and spectra of charged particle species was performed by an experiment including four charged particle sensor systems, within 20 Saturn radii of the planet. Increases in the intensity of 0.5- to 1.8-MeV protons within 15 Saturn radii indicate the trapping and acceleration of particles in the dipole field region, while a decrease in proton intensity between seven and four Saturn radii is attributed to absorption by Dione and Enceladus and possibly ring material as well. Proton and electron intensity distributions are found to be axially symmetric within four Saturn radii, indicating a centered dipole aligned with the planetary rotation axis. Trapped radiation absorption at the orbit of Mimas is analyzed to obtain an upper limit of 4 x 10 to the -8th Saturn radii-squared/sec to the inward diffusion coefficient; an absorption-like feature observed at L = 2.5 is attributed to a previously unidentified satellite of diameter less than 200 km and semimajor axis 2.51 Saturn radii. Radiation absorption by the newly discovered F ring was also observed, however beneath the A, B and C rings a low flux of high-energy electrons was detected.

Simpson, J. A.↗
NASA NTRS2004

The Legacy of the Low Temperature Microgravity Physics Facility

The Jet Propulsion Laboratory (JPL) has been building the Low Temperature Microgravity Physics Facility (LTMPF) as a multi-user research facility for the International Space Station. Because of the recent Presidential Exploration Initiative placed on NASA, NASA has informally told JPL to phase out the development of the LTMPF, assuming a suspension of funding at the end of fiscal year 2004. Over the last five years of development of the Facility, a tremendous legacy of both scientific and technical progress has been made, and a significant amount of flight hardware has been built. During these last few months of remaining funding, the LTMPF plans on finishing some remaining development efforts, archiving the hardware (flight and engineering models), software, and capturing the knowledge generated for possible future missions. These possible future missions could include gravitational or relativistic physics experiments (around the Earth or the Moon), charged particle physics experiments away from the Earth, possible other fundamental physics experiments in a Code U-developed free flyer orbiting the Earth, or even gravitational mapping experiments around the Moon or possibly Mars. LTMPF-developed technologies that are likely to have substantial impact on such future missions include SQUID magnetometers and thermometers, ultra-high-performance cryogenics, and high-Q superconducting resonators.

Larson, Melora↗
NASA NTRS1992

Origins of Energetic Ions in the Earth's Magnetosheath

The analysis and interpretation of the combined scientific data from the Hot Plasma Composition Experiment (HPCE) and the Charge Energy Mass (CHEM) spectrometer on the Active Mesospheric Particle Tracer Experiment (AMPTE) Charge Composition Explorer (CCE) spacecraft are discussed. These combined data sets have and will be used to survey the energetic ion environment in the Earth's magnetosheath to determine the origins and relative strengths of the energetic ion populations found there. A computer code was developed to analyze and interpret the data sets. The focus of the first year was on the determination of the contribution of leaked magnetospheric protons to the total energetic proton population. Emphasis was placed on intervals when the AMPTE spacecraft was in the plasma depletion layer because it was argued that in this region, only the leaked population contributes to the energetic ion population. Manipulation of the CHEM data and comparison of the CHEM and HPCE data over their common energy range near the magnetopause also contributed directly to a second study of that region.

Fuselter, S. A.↗
NASA NTRS1988

The Spacelab 2 mission - An overview

A summary is presented of the results of experiments on the Spacelab 2 mission, which was flown on the Shuttle Orbiter between July 29 and August 6, 1985. The background and flight of the mission and the payload configuration are examined. The experiments include the Ejectable Plasma Diagnostics Package, Vehicle Charging and Potential Experiment, and plasma detection experiments. Life science experiments include studies of the effects of spaceflight on the growth of plant tissues and perturbations of bone and calcium homeostasis in flight crew members. Solar studies include the Solar UV Spectral Irradiance Monitor, the Coronal Helium Abundance Spacelab Experiment, the High Resolution Telescope and Spectrograph, the Solar Magnetic and Velocity Field Measurement System, and the Solar Optical Universal Polarimeter. Additional experiments include observations with a small He-cooler IR telescope, Hard X-ray imaging of galaxy clusters and extended X-ray sources, the composition and energy spectra of cosmic ray nuclei, and the properties of superfluid He in zero gravity.

Urban, Eugene W.↗
NASA NTRS1974

Instrument to measure energy and charge of low energy interplanetary particles

An experiment to measure the charge composition and energy spectra of ultra low energy charged particles in interplanetary space has been developed and launched on the IMP 8 (Explorer 50) satellite on Oct. 26, 1973. The instrument consists of two separate sensors sharing common electronics. One of these sensors uses a thin window gas proportional counter to measure the rate of energy loss and a totally depleted silicon surface barrier detector to measure total energy of incoming particles. The energy range for two dimensional analysis extends from 300 KeV to 2.5 MeV for protons and 60 KeV/nucleon to 25 MeV/nucleon for iron with excellent resolution of individual chemical elements. The other sensor combines electrostatic deflection with total energy measurements in silicon surface barrier detectors to give the ionic charge and kinetic energy of the particle.

Tums, E.↗
NASA NTRS1983

Vehicle charging and potential on the STS-3 mission

An electron gun with fast pulse capability was used in the vehicle charging and potential experiment carried on the OSS-1 pallet to study dielectric charging, return current mechanisms, and the techniques required to manage the electrical charging of the orbiter. Return currents and charging of the dielectrics were measured during electron beam emission and plasma characteristics in the payload bay were determined in the absence of electron beam emission. The fast pulse electron generator, charge current probes, spherical retarding potential analyzer, and the digital control interface unit which comprise the experiment are described. Results show that the thrusters produce disturbances which are variable in character and magnitude. Strong ram/wake effects were seen in the ion densities in the bay. Vehicle potentials are variable with respect to the plasma and depend upon location on the vehicle relative to the main engine nozzles, the vehicle attitude, and the direction of the geomagnetic field.

Williamson, R.↗
NASA NTRS1999

Photoelectric Charging of Dust Particles

Laboratory experiments have been performed on the photoelectric charging of dust particles which are either isolated or adjacent to a surface that is also a photoemitter. We find that zinc dust charges to a positive potential of a few volts when isolated in vacuum and that it charges to a negative potential of a few volts when passed by a photoemitting surface. The illumination is an arc lamp emitting wavelengths longer than 200 nm and the emitting surface is a zirconium foil.

Sickafoose, A.↗
NASA NTRS1988

Optimization of low gravity materials processing experiments using expert systems

The use of an expert system for the control of materials processing experiments in a facility such as the Space Station provides a number of attractive features for insuring that certain critical process parameters can be used to optimize the productivity of the materials processing experiments. The proposed approach to implementation of an expert system utilizes a knowledge base of desired process characteristics which will provide the desired results. The knowledge base for each experiment will be created in conjunction with the scientific investigator in charge of the experiment. Improvements to the knowledge base will be expanded to include self learning sessions in ground based experiments in order to teach the expert system how to respond to perturbations in the process and update the knowledge base on what process change should be implemented in order to reach the desired end product. Design considerations using an on-line real time expert system such as PICON is studied. The types of experiments evaluated include several types of solidification experiments which will be performed on the Space Station.

Workman, Gary L.↗
NASA NTRS2001

Dust Particle Charging near Surfaces in Space

Dust dynamics, as observed on the lunar surface, are thought to be due to the interaction between charged dust and a photoelectron sheath above the surface. We perform experiments on the charging and dynamics of dust near a surface having a sheath Additional information is contained in the original extended abstract.

Sickafoose, A. A.↗
NASA NTRS1993

Numerical quasi-linear study of the critical ionization velocity phenomenon

The critical ionization velocity (CIV) for a neutral barium (Ba) gas cloud moving across the static magnetic field is studied numerically using quasi-linear equations and a parameter range which is typical for the shaped-charge Ba gas release experiments in space. For consistency the charge exchange between the background oxygen ions and neutral atoms and its reverse process, as well as the excitation of the neutral Ba atoms, are included. The numerical results indicate that when the ionization rate due to CIV becomes comparable to the charge exchange rate the energy lost to the ionization and excitation collisions by the superthermal electrons exceeds the energy gain from the waves that are excited by the ion beam. This results in a CIV yield less than the yield by the charge exchange process.

Moghaddam-Taaheri, E.↗
NASA NTRS1995

Charge, energy and LET spectra of high LET primary and secondary particles in CR-39 plastic nuclear track detectors of the P0006 experiment

We have measured the charge, energy and linear energy transfer (LET) spectra of about 800 high LET (LET(sub infinity) H2O greater than 50 keV/micron) particles in CR-39 plastic nuclear track detectors in the P0006 experiment of LDEF. Primary particles with residual range at the reference surface greater than about 2 microns and secondary particles produced in the detector material with total range greater than about 4 microns were measured. We have used a multi-etch technique and an internal calibration to identify and measure the energy of the particles at the reference surface. The LET spectrum was obtained from the charge and energy distribution of the particles.

Csige, I.↗
NASA NTRS1985

Particle acceleration due to shocks in the interplanetary field: High time resolution data and simulation results

Data were examined from two experiments aboard the Explorer 50 (IMP 8) spacecraft. The Johns Hopkins University/Applied Lab Charged Particle Measurement Experiment (CPME) provides 10.12 second resolution ion and electron count rates as well as 5.5 minute or longer averages of the same, with data sampled in the ecliptic plane. The high time resolution of the data allows for an explicit, point by point, merging of the magnetic field and particle data and thus a close examination of the pre- and post-shock conditions and particle fluxes associated with large angle oblique shocks in the interplanetary field. A computer simulation has been developed wherein sample particle trajectories, taken from observed fluxes, are allowed to interact with a planar shock either forward or backward in time. One event, the 1974 Day 312 shock, is examined in detail.

Kessel, R. L.↗
NASA NTRS1982

Studies of beam plasma interactions in a space simulation chamber using prototype Space Shuttle instruments

In March, 1981, electron beam experiments were conducted in a large space simulation chamber using equipment destined to be flown aboard NASA's Office of Space Science-1 pallet (OSS-1). Two major flight experiments were involved. They include the Vehicle Charging and Potential (VCAP) experiment and the Plasma Diagnostics Package (PDP). Apparatus connected with VCAP included a Fast Pulse Electron Gun (FPEG), and a Charge and Current Probe (CCP). A preliminary view is provided of the results obtained when the electron emissions were held steady over relatively long periods of time such that steady state conditions could be obtained with respect to the electron beam interaction with the neutral gases and plasma of the vacuum chamber. Of particular interest was the plasma instability feature known as the Beam Plasma Discharge. For the present experiments the FPEG was used in a dc mode with a range of currents of 2 to 80 mA at a beam energy of 970 eV. Attention is given to the emissions of VLF and HF noise associated with the dc beam.

Banks, P. M.↗
NASA NTRS1980

First results of material charging in the space environment

A satellite experiment, designed to measure potential charging of typical thermal-control materials at near-geosynchronous altitude, was flown as part of the Spacecraft Charging at High Altitudes program. Direct observations of charging of typical satellite materials in a natural charging event (greater than or equal to 5 keV) are presented. The results show some features which differ significantly from previous laboratory simulations of the environment.

Mizera, P. F.↗
NASA NTRS1981

First results of material charging in the space environment

A satellite experiment, designed to measure potential charging of typical thermal control materials at near geosynchronous altitude, was flown as part of the SCATHA program. Direct observations of charging of typical satellite materials in a natural charging event ( 5 keV) are presented. The results show some features which differ significantly from previous laboratory simulations of the environment.

Stevens, N. J.↗
NASA NTRS1980

POLAR 5 - An electron accelerator experiment within an aurora. III - Evidence for significant spacecraft charging by an electron accelerator at ionospheric altitudes

The POLAR 5 rocket experiment carried an electron accelerator on a 'daughter' payload which injected a 0.1 A beam of 10 keV electrons in a pulsed mode every 410 ms. With spin and precession, injections were made over a wide range of pitch angles. Measurements from a double probe electric field instrument and from particle detectors on the 'mother' payload and from a crude RPA on the 'daughter' payload are interpreted to indicate that the 'daughter' charges to a potential between several hundred volts and 1 kV. The neutralizing return current to the 'daughter' is shown to be asymmetrically distributed with the majority being collected from the direction of the beam. The additional electrons necessary to neutralize the daughter are thought to be produced and heated through beam-plasma interactions postulated by Maehlum et al. (1980) and Grandal et al. (1980) to explain the particle and optical measurements. Significant electric fields emanating from the charged 'daughter' and the beam are seen at distances exceeding 100 m at the 'mother' payload.

Jacobsen, T. A.↗