Aeronomy report no. 73: Analysis of sounding rocket data from Punta Chilca, Peru

A technique is described for measuring electron concentrations in the lower portion of the ionosphere above Punta Chilca. A radio-propagation experiment for measuring Faraday rotation is combined with a dc/Langmuir probe experiment for measuring electron current. The results obtained from the analysis of radio and probe data from Nike Apache 14.532, which was launched at 20:26 UT on May 28, 1975, at a solar zenith angle of 60 deg are presented. A comparison of the profiles of electron concentration indicates that the value of the maximum ionization in the D region under quiet conditions is proportional to the square of the cosine of the solar zenith angle

FORTRAN programs for calculating lower ionosphere electron densities and collision frequencies from rocket data

FORTRAN programs for calculating lower ionosphere electron densities and collision frequencie

Low-latitude ionospheric D region dependence on solar zenith angle

Phase and amplitude measurements of VLF radio signals on a short, nearly all-sea path between two Hawaiian Islands are used to find the height and sharpness of the lower edge of the daytime tropical D region as a function of solar zenith angle (SZA). The path used was from U.S. Navy transmitter NPM (21.4 kHz) on Oahu to Keauhou, 306 km away, on the west coast of the Big Island of Hawaii, where ionospheric sensitivity was high due to the destructive interference between the ionospherically reflected wave and the ground wave, particularly around the middle of the day. The height and sharpness are thus found to vary from H′ = 69.3 ± 0.3km and β = 0.49 ± 0.02 km-1 for SZA ~10°, at midday, to H′ >80 km and β ~ 0.30 km-1 as the SZA approached ~70°–90°, near dawn and dusk for this tropical path. Additional values for the variations of H′ and β with solar zenith angle are also found from VLF phase and amplitude observations on other similar paths: the short path, NWC to Karratha (in NW Australia), and the long paths, NWC to Kyoto in Japan and NAU, Puerto Rico, to St. John’s Canada. Significant differences in the SZA variations of H′ and β were found between low and middle latitudes resulting from the latitudinally varying interplay between Lyman α and galactic cosmic rays in forming the lower D region. Both latitude ranges showed β<0.30 km-1 during sunrise/sunset conditions. 1

Thin film organic thermoelectric generator based on tetrathiotetracene

Thin films of p- and n- type organic semiconductors for thermo-electrical (TE) applications are produced by doping of tetrathiotetracene (TTT). To obtain p-type material TTT is doped with iodine during vacuum deposition of thin films or by post-deposition doping using controlled exposure to iodine vapors. Thermal co-deposition in vacuum of TTT and TCNQ is used to prepare n-type thin films. The attained thin films are characterized by measurements of Seebeck coefficient and electrical conductivity. Seebeck coefficient and conductivity could be varied by altering the doping level. P-type TTT:iodide thin films with a power factor of 0.52 μWm-1K-2, electrical conductivity of 130 S m-1 and Seebeck coefficient of 63 μV K-1 and n-type TCNQ:TTT films with power factor of 0.33 μWm-1K-2, electrical conductivity of 57 S m-1 and Seebeck coefficient of -75 μV K-1 are produced. Engineered deposition of both p- and n-type thermoelectric conducting elements on the same substrate is demonstrated. A proof of concept prototype of planar thin film TE generator based on a single p-n couple from the organic materials is built and its power generation characterized

Lower ionosphere monitoring by the South America VLF Network (SAVNET): C-region occurrence and atmospheric temperature variability

Daily profiles of phase measurements as observed on fixed VLF-paths generally show a transient phase advance, followed by a phase delay, for about 90 minutes after sunrise hours. This is indicative of a reflecting ionospheric C-region developing along the terminator line at an altitude below the normal D-region. The suggested occurrence of a C-region is consistent with rocket measurements made in the 1960's, showing a maximum of the electron density between 64 and 68 km, and by radio sounding in the 1980's. In order to correctly describe the properties of the phase effect associated with the presence of a C-region, it is important to understand the subionospheric propagation characteristics of the VLF-paths. In this paper, we analyze the variations presented by the temporal properties of the VLF narrow-band phase effect, and determined a parameter associated with the appearance of the C-region at sunrise hours observed by receivers from the South America VLF Network (SAVNET). Periodic patterns emerge from the parameter curves. Two distinct temporal behavior regimes can be identified: one exhibiting slow variations between March and October, and another one exhibiting faster variations between October and March. Solar illumination conditions and the geometrical configuration of the VLF paths relative to the sunrise terminator partly explain the slow variation regime. During periods of faster variations, we have observed good association with atmospheric temperature variability found in the measurements of the TIMED-SABER satellite instrument, which we assume to be related to the Winter Anomaly atmospheric phenomenon. However, when comparing the parameter time series with temperature curves, no direct one-to-one correspondence was found for transient events