Showing papers on "TEC published in 1984"

Relationship between nighttime total electron content enhancements and VHF scintillations at the equator

Abstract: The relationship between nighttime enhancements in total electron content (TEC) and VHF amplitude scintillations has been studied using the ATS 6 satellite data obtained from two closely located equatorial stations (Ootacamund and Thumba) for the period October 1975 to July 1976. The results show that the occurrence and various other characteristics of the TEC enhancements are correlated to corresponding characteristics of the scintillation index SI. The peak value of the SI index is found to increase linearly with that of the TEC enhancement until it reaches the saturation value of nearly 1 for the peak TEC enhancement of about 0.6×1017 m−2. Both phenomena start mostly prior to midnight with the TEC enhancement being delayed by 1 to 1½ hours with respect to the scintillations. The half-amplitude duration of the scintillation enhancement is greater than that of the TEC by a factor of 1 to 2. The intensity and duration of both phenomena are found to be maximum at equinox and minimum in summer. From the results it is clear that the TEC enhancements cannot be regarded as a source for the small-scale irregularities but rather they both seem to depend on the postsunset vertical drifts in the F layer.

Spatial correlation of the ionospheric total electron content at the equatorial anomaly crest

Abstract: The spatial correlation of the ionospheric total electron content (TEC) at the equatorial anomaly crest was studied by recording Faraday rotation angle of the ETS-II geostationary satellite at Lunping and Kaohsiung whose subionospheric points are located at 23.0/sup 0/N, 121.0/sup 0/N, and 20.9/sup 0/N, 121.1/sup 0/E, respectively, and are about 280 km apart. The results show that the spatial correlation of TEC at the equatorial crest region is smaller than that at other places. The day-to-day variabilities of TEC differences between two subionospheric points are quite large. The day-to-day variabilities of the fountain effect seem to play an important role.

Spatial variability of total electron content in the eastern Mediterranean region

Abstract: Faraday-rotation observations were conducted at Haifa, Israel (32.87N, 35.09E), and Athens, Greece (37.97N, 23.72E), during the maximum phase of the current solar cycle using the VHF beacon of the SIRIO satellite. The subionospheric points (at 420km) are (29.9N, 27.9E) and (34.5N, 18.4E), and the subionospheric L-shell values are 1.24 and 1.37, respectively. Expected latitudinal and local time differences in total electron content (TEC) for the two locales are observed. However, the Haifa data are characterized by generally occurring, seasonally independent, large postsunset electron content maxima which are absent for the Athens data. Furthermore, the postsunset increases would appear to be a solar-maximum phenomenon, as they are not observed during the minimum phase of the solar cycle. The postsunset increases are attributed to electron fluxes arriving from the equatorial regions along the magnetic lines of force. The correlation coefficients of hourly TEC at the Haifa/Athens locales exhibit a seasonally independent diurnal variation with minimum values at night and maximum values generally at the end of the buildup phase of TEC variation. The daytime ratios of the standard deviation of TEC to the average TEC are generally seasonally independent and behave quite similarly at the two locals, with daytime values below aboutmore » 25%.« less

Thermionic Energy Conversion for Space-Power and Terrestrial-Topping Applications

Abstract: Thermionic energy conversion (TEC) can contribute effectively through high-temperature high-power production of electricity in space and on earth. Among its other advantages TEC offers great Carnot efficiencies while operating with no moving parts. In space-power and terrestrial-topping applications TEC environmental conditions differ drastically. But for high levels and densities of space nuclear power (SNP) as well as economy and efficiency of power-plant augmentation on earth the desirable internal TEC characteristics and capabilities exhibit significant similarities. Therefore related TEC power projections and problem solutions discussed in this paper impinge on important industrial and political implications of the future. Such discussions should derive from professional qualifications. In that vein both authors participated for many years in national R&D activities emphasizing TEC: the pre-1973 SNP, post-1973 NASA NEP, DOE Fossil Energy, Air Force and DOE SP-100 programs. The first author served as national Technical Manager for the NASA-NEP and DOE-Fossil-Fuel TEC R&D programs. These backgrounds form the basis for the present paper.

Temperature-dependent variable-capacity circuit, and hyperfrequency temperature-dependent oscillator frequency-stabilized with the aid of such a circuit

Abstract: «Circuit formant une capacite variable en fonction de la temperature et oscillateur hyperfrequences stabilise en frequence en fonction de la temperature a l'aide d'un tel circuit» "Circuit forming a variable capacity depending on the temperature and microwave oscillator frequency stabilized by a function of temperature using such a circuit" Circuit de stabilisation pour un oscillateur libre a TEC en AsGa, dans lequel la stabilisation en frequence en fonction de la temperature est obtenue par la variation de capacite grillecanal d'un TEC de compensation place dans le circuit d'ajustage de la frequence de l'oscillateur et commande par une tension ajustee en fonction de la temperature par les variations du point de fonctionnement d'un reseau de diodes Schottky ou de TEC. stabilization circuit for a free oscillator FET GaAs, wherein the frequency stabilization depending on the temperature is obtained by varying grillecanal ability of a TEC compensation placed in the Frequency adjusting circuit of the oscillator and controlled by a voltage adjusted according to the temperature changes in the operating point of a Schottky diode array or TEC. Application: Application: circuits monolithiques integres a TEC a charges resisti- ves en AsGa pour les applications hyperfrequences par exemple pour le traitement des signaux de television a 12 GHz. monolithic integrated circuits FET loads ves resistivity GaAs for microwave applications eg for processing television signals at 12 GHz.