Engineering Papers⌕ Search

Engineering topics

Burch, J. L.

Publications and source records attributed to Burch, J. L..

At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Dependence of the latitude of the cleft on the interplanetary magnetic field and substorm activity

The latitudinal motion of the cleft (the polar cusp) associated with the southward interplanetary magnetic field (IMF) and substorm activity is examined. The cleft location is identified on the basis of the location of midday auroras and of electron precipitation by the OGO 4 and ISIS 1 satellites. It is found that the IMF and substorm activity control independently the latitude of the cleft and that they can shift the cleft location by 3 or 4 deg under average conditions.

Kamide, Y.↗
NASA NTRS1976

Substorm effects observed in the auroral plasma

The effects of substorm temporal development on high-latitude particle precipitation and ionospheric convection patterns near midnight were studied with the aid of data from Atmosphere Explorer C. During quiet periods generally Maxwellian electron precipitation is observed from the central plasma sheet, which is completely contained within the sunward flow region. As substorms grow and begin to recover, a strong sunward flow appears within the high latitude ionospheric electron trough, equatorward of the central plasma sheet electron precipitation. Intense inverted-V electron structures consistent with strong electrostatic acceleration appear near the Harang discontinuity and extend poleward to the polar cap boundary. Then the trough flow weakens, the Harang discontinuity becomes a gradual reversal, and the electron inverted-V precipitation becomes localized at the polar cap boundary.

Burch, J. L.↗
NASA NTRS1975

Substorm-associated reconfiguration of the dusk side equatorial magnetosphere - A possible source mechanism for isolated plasma regions

A rapid reconfiguration of the dusk side magnetosphere was observed near the magnetic equator by particle and field experiments aboard Explorer 45 at 1715 UT on June 17, 1972. Following the onset of an 800-gamma negative bay in the auroral zone, Explorer 45, inbound at 1700 MLT and L about 5, observed a sharp dropout of outer zone electrons. Simultaneously, the plasma density dropped from a level typical of the plasmasphere to one typical of the ion trough, and plasma sheet proton fluxes increased, producing a 100-gamma depression in B, in a shift to a taillike configuration. Outer zone electrons with pitch angles near 45 deg returned with delay times consistent with injection near midnight at the time of dropout and eastward drift to the dusk meridian. Approximately 45 min after the reconfiguration, the satellite reentered the plasmasphere, and the electron fluxes returned to previous levels. In the next orbit, approximately 6 hours later, a region of isolated plasma was detected near apogee at 1400 MLT. There is therefore circumstantial evidence that the type of magnetospheric reconfiguration observed here is responsible for the detachment of regions of cold plasma from the plasmasphere.

Barfield, J. N.↗
NASA NTRS1974

Automatically operable self-leveling load table

A self-leveling load table is described which is automatically maintained level by selectively opening and closing solenoid valves for inserting and removing air from chambers under the table. The table is floated in a fluid by nine air chambers beneath the top of the table. These chambers are open at the bottom and four oppositely located chambers are used for leveling the table by having the air increased or decreased by means of a flexible hose. Air bearing pendulums are used for selectively energizing solenoid valves which either apply pressurized air to the chamber or evacuate air from the chamber by means of a vacuum source.

Burch, J. L.↗
NASA NTRS1974

Self-leveling load table

Table floats in tank of water and has air compartments underneath. Table height and level are controlled by automatic adjustment or air pressure within these compartments.

Burch, J. L.↗
NASA NTRS1974

Observations of interactions between interplanetary and geomagnetic fields

Magnetospheric effects associated with variations of the north-south component of the interplanetary magnetic field (IMF) are examined in light of recent experimental and theoretical results. Although the occurrence of magnetospheric substorms is statistically related to periods of southward IMF, the details of the interaction are not understood. In particular, attempts to separate effects resulting directly from the interaction between interplanetary and geomagnetic fields from those associated with substorms have produced conflicting results. It is possible, however, to say with some assurance that the transfer of magnetic flux from the dayside to the nightside magnetosphere, as evidenced by equatorward motion of the polar cusp and increases of the magnetic energy density in the lobes of the geomagnetic tail, is a direct consequence of the southward IMF. On the other hand, the formation of a macroscopic X-type neutral line at tail distances less than 35 earth radii appears to be a substorm phenomenon.

Burch, J. L.↗
NASA NTRS1974

AE-LEE measurements at low and mid latitude

Shortly after the Low Energy Electron Experiment (LEE) on the Atmosphere Explorer-C was turned on following launch, an unexpected phenomenon was encountered at mid-latitudes, a counting rate was acquired with one maximum per roll. Recent analysis shows that these counting rates occur when the detectors are looking in the ram direction of the spacecraft and the spacecraft is near perigee, and are indeed not due to properly analyzed charged particles. After showing the probable cause of these counting rates, some upper limits to true fluxes at low altitudes in the energy range 200 eV to 25 keV from the LEE experiment are shown. OGO-4 data taken at mid-latitudes are included.

Hoffman, R. A.↗
NASA NTRS1974

Coordinate transformations for studies of interactions between interplanetary and geomagnetic fields

A graphical procedure is provided for performing coordinate transformations between the geocentric-solar-equatorial, geocentric-solar-ecliptic and geocentric-solar-magnetospheric coordinate systems. The procedure is designed to facilitate intercomparison of previous studies of interactions between interplanetary and geomagnetic fields that made use of these coordinate systems. The interaction in the geocentric-solar-magnetosphere system has been shown to give the most consistent results.

Burch, J. L.↗
NASA NTRS1973

Observations of interactions between interplanetary and geomagnetic fields

Magnetospheric effects associated with variations of the north-south component of the interplanetary magnetic field are examined in light of recent recent experimental and theoretical results. Although the occurrence of magnetospheric substorms is statistically related to periods of southward interplanetary magnetic field, the details of the interaction are not understood. In particular, attempts to separate effects resulting directly from the interaction between the interplanetary and geomagnetic fields from those associated with substorms have produced conflicting results. The transfer of magnetic flux from the dayside to the nightside magnetosphere is evidenced by equatorward motion of the polar cusp and increases of the magnetic energy density in the lobes of the geomagnetic tail. The formation of a macroscopic X-type neutral line at tail distances less than 35 R sub E appears to be a substorm phenomenon.

Burch, J. L.↗
NASA NTRS1973

Small portable speed calculator

Calculator is adapted stopwatch calibrated for fast accurate measurement of speeds. Single assembled unit is rugged, self-contained, and relatively inexpensive to manufacture. Potential market includes automobile-speed enforcement, railroads, and field-test facilities.

Burch, J. L.↗
NASA NTRS1973

High-latitude proton precipitation and light ion density profiles during the magnetic storm initial phase.

Measurements of precipitating protons and light ion densities by experiments on Ogo 4 indicate that widespread proton precipitation occurs in predawn hours during the magnetic storm initial phase from the latitude of the high-latitude ion trough, or plasmapause, up to latitudes greater than 75 deg. A softening of the proton spectrum is apparent as the plasmapause is approached. The separation of the low-latitude precipitation boundaries for 7.3-keV and 23.8-keV protons is less than about 1 deg, compared with a 3.6-deg separation that has been computed by using the formulas of Gendrin and Eather and Carovillano. Consideration of probable proton drift morphology leads to the conclusion that protons are injected in predawn hours, widespread precipitation occurring in the region outside the plasmapause. Protons less energetic than 7 keV drift eastward, whereas the more energetic protons drift westward, producing the observed dawn-dusk asymmetry for the lower-energy protons.

Burch, J. L.↗
NASA NTRS1973

Rate of erosion of dayside magnetic flux based on a quantitative study of the dependence of polar cusp latitude on the interplanetary magnetic field

In a consideration of only those periods when the delay time from the interplanetary observing position to the magnetosphere is less than 5 minutes, it is found that, irrespective of substorm activity: (1) The 45 minute average value of interplanetary B(z) predicts the latitudes of the poleward and equatorward boundaries of polar cusp electron precipitation with rms errors of 1.34 deg and 1.16 deg respectively; (2) Both boundaries more equatorward by about 5 deg as B(z) varies from 1 to -6 gammas, the cusp remaining about 40 deg wide; (3) The amount of flux added to the polar cap is about 9.2 percent of the total southward flux impingent on the magnetosphere in the previous 45 minutes; (4) As B(z) becomes more positive, the equatorward boundary moves only slightly more poleward (1/2 deg between B(z) = 2 gammas and B(z) = 6 gammas, while the poleward boundary moves significantly toward higher latitudes, resulting in a cusp approximately 7 deg wide for B(z) = 6 gammas.

Burch, J. L.↗
NASA NTRS1973

Electron precipitation patterns and substorm morphology.

Statistical analysis of data from the auroral particles experiment aboard OGO 4, performed in a statistical framework interpretable in terms of magnetospheric substorm morphology, both spatial and temporal. Patterns of low-energy electron precipitation observed by polar satellites are examined as functions of substorm phase. The implications of the precipitation boundaries identifiable at the low-latitude edge of polar cusp electron precipitation and at the poleward edge of precipitation in the premidnight sector are discussed.

Hoffman, R. A.↗
NASA NTRS1973

Low-energy electron experiment for Atmosphere Explorer-C and -D.

The low-energy electron experiment will provide differential measurements of the energy influx and angular distributions of electrons and protons on the Atmosphere Explorer-C and -D missions. The detectors consist of cylindrical electrostatic analyzers for species and energy selection and Spiraltron electron multipliers as particle sensors. The C version will contain three detectors, two measuring electrons and protons from 0.2 to 25 keV in 16 logarithmically spaced steps and one measuring 5 keV electrons continuously. Angular distributions will be acquired utilizing the spin of the spacecraft. The D version will contain 19 detectors, one proton-stepped energy analyzer, and two electron-stepped energy analyzers at two different angles, again over the energy range 0.2 to 25 keV.

Hoffman, R. A.↗
NASA NTRS1973

High latitude proton precipitation and light-ion density profiles during the magnetic storm initial phase

Measurements of precipitating protons and light ion densities by experiments on OGO-4 indicate that widespread proton precipitation occurs in predawn hours during the magnetic storm initial phase from the latitude of the high-latitude ion trough, or plasmapause , up to Lambda 75 deg. A softening of the proton spectrum is apparent as the plasmapause is approached. The separation of the low-latitude precipitation boundaries for 7.3 kev and 23.8 kev protons is approximately 1 deg, compared with a 3.6 deg separation which has been computed using the formulas of Gendrin and Eather and Carovillano. Consideration of probable proton drift morphology leads to the conclusion that protons ase injected in predawn hours, with widespread precipitation occurring in the region outside the plasmapause. Protons less energetic than approximately 7 kev drift eastward, while the more energetic protons drift westward, producing the observed dawn-dusk asymmetry for the lower-energy protons.

Burch, J. L.↗