Showing papers on "TEC published in 1982"

Optical signature of an ionospheric hole

Abstract: Simultaneous radio and optical diagnostics of a large, artificially-induced ionospheric modification were conducted during the June 1981 launch of a weather satellite. Intensified imaging and photometer observations at 6300 A, along the same ray path as VHF polarimeter measurements of the ionosphere's total electron content (TEC), were made while the rocket plume caused disturbances. A rapid TEC chemical depletion, on the order of -16.8 x 10 to the 12th el/sq cm, caused a burst of 6300 A radiation which expanded over 60 deg of the sky, with a peak intensity of almost 9 k R. Atmospheric diffusion and O(1D) quenching rate theoretical estimates were then tested, using the event as an active space plasma experiment.

The electron content and its variations at Natal, Brazil

Abstract: The Faraday rotation and amplitude data for the period September 1978 through August 1979, recorded from the geostationary satellite SMS 1 (90°W) at Natal (5.9°S, 35.2°W), have been utilized to study the behavior of total electron content (TEC). Apart from diurnal and seasonal behavior of TEC, two characteristic features of the nighttime ionosphere are discussed: (1) a postsunset enhancement in TEC which lasts for several hours following the rapid sunset decrease and (2) the sharp, isolated changes in TEC. In particular, relating to phenomenon 2, the depletions in TEC are usually accompanied by a simultaneous increase in fading rate, scintillation index, and amplitude level, while the enhancements are accompanied by a simultaneous decrease in fading rate, scintillation index, and amplitude level. The statistics of their occurrence and nature are described. The average behavior of the signal amplitude after propagating through either a depleted or an enhanced ionosphere is modeled theoretically and shown to be in agreement with the observed experimental behavior.

Total electron content structure in the Middle East

Abstract: Polarization rotation data recorded from the geostationary satellite SIRIO at Haifa, Israel, have been used to study the structure and variability of the total electron content (TEC) during the maximum phase of the current solar cycle. In addition to the overall diurnal and seasonal variation, the TEC is regularly modulated by the effects of traveling ionospheric disturbances (TID's). The behavior of TID's in terms of their frequency of occurrence, amplitude, period, and time of occurrence is seasonally dependent. Comparison with average behavior of TEC and related parameters observed during the minimum phase indicates the extent of the solar cycle variation.

The Response of the Total Electron Content of the Ionosphere Over North America to the Total Solar Eclipse of 26 February 1979.

Abstract: : Ionospheric total electron content (TEC) observations were carried out from eight stations during the total solar eclipse of 26 February 1979 over North America by monitoring changes in the Faraday rotation of the plane of polarization of vhf signals from geostationary satellites Additionally, TEC data from ionospheric group-delay measurements were made at Vanderberg, Calif, from two 12-h synchronous NAVSTAR/Global Positioning System (GPS) satellites which crossed over the eclipsed region Local times of totality of the eclipse in the ionospheric observed from the various stations ranged from 0730 h to 1400 h Depletion of the ionospheric TEC from the non-eclipse average behavior varied up to a maximum of 40 percent for the ionosphere experiencing 100 percent eclipse Maximum TEC depletion occurred, on average, 33 min after maximum obscuration Most of the stations showed a rapid rate of depletion of TEC about 30 min after first contact, the rate of depletion reaching a minimum value at or before maximum obscuration Before fourth contact was reached, the rate of increase of TEC generally had overshot the non-eclipse day average, gradually returning to that average after fourth contact Ionosonde data showed that the peak density of the F region and the TEC varied by approximately the same amount at those stations for which the E region had formed before first contact of the eclipse Slab thickness, a first order F-region shape parameter, was not significantly changed during the eclipse (Author)

Parametric performance analysis of steam-injected gas turbine with a thermionic-energy-converter-lined combustor

Abstract: The performance of steam-injected gas turbines having combustors lined with thermionic energy converters (STIG/TEC systems) was analyzed and compared with that of two baseline systems; a steam-injected gas turbine (without a TEC-lined combustor) and a conventional combined gas turbine/steam turbine cycle. Common gas turbine parameters were assumed for all of the systems. Two configurations of the STIG/TEC system were investigated. In both cases, steam produced in an exhaust-heat-recovery boiler cools the TEC collectors. It is then injected into the gas combustion stream and expanded through the gas turbine. The STIG/TEC system combines the advantage of gas turbine steam injection with the conversion of high-temperature combustion heat by TEC's. The addition of TEC's to the baseline steam-injected gas turbine improves both its efficiency and specific power. Depending on system configuration and design parameters, the STIG/TEC system can also achieve higher efficiency and specific power than the baseline combined cycle.