Engineering topics
Publications and source records attributed to Davis, T. N..
Five Nike-Tomahawk rockets were flown to measure perturbations in the magnitude of the geomagnetic field due to auroral electrojets. The dates and locations of the rocket launches are given along with a brief explanation of payloads and instrumentation. Papers published as a result of the project are listed. An abstract is included which outlines the scientific results from one of the flights.
The geophysical disturbance environment was quiet during the NASA/MPE barium release at 5 earth radii on September 21, 1971. At the time of the release, the magnetosphere was in the late recovery phase of a principal magnetic storm, the provisional Dst value was -13 gammas, and the local horizontal disturbance at Great Whale River was near zero. Riometer and other observations indicated low-level widespread precipitation of high-energy electrons at Great Whale River before, during, and after the release. Cloudy sky at this station prevented optical observation of aurora. No magnetic or ionospheric effects attributable to the barium release were detected at Great Whale River.
The feasibility of generating artificial auroras by injecting electrons into the upper atmosphere was investigated by using an electron accelerator aboard an Aerobee 350 rocket. Four of the artificial auroral rays were detected and recorded by two geophysical sites separated enough to enable the spatial coordinates of the rays to be determined by triangulation. It was found that (1) the beam remained well collimated; (2) most of the initial beam energy was deposited in the atmosphere; (3) plasma instabilities did not play a significant role; and (4) the orientations of the rays were determined with sufficient accuracy to improve the knowledge of the earth's magnetic field over the Virginia coast. The publications resulting from this research are listed.
Two field-line tracing experiments were conducted on an L = 1.26 magnetic flux tube over Kauai, Hawaii. Barium vapor was created by the detonation of a highly explosive shaped charge aligned with the geomagnetic field at a 467-km altitude. Barium ions traveled along the field line to the conjugate ionosphere in a tube 3 to 5 km in diameter, producing a visible streak along the entire 6900-km path length. Electric fields perpendicular to the magnetic field caused the ions to drift away from the true conjugate during transit, but extrapolation from subsequent ion drift rates allowed the conjugate to be identified and compared with several field models. Differing ion drift rates and directions at the conjugate points indicated that the electric field is not transferred unattenuated along field lines.
Results of simultaneous observation of a fast wave event from the Ester Dome Observatory (EDO) near College, Alaska, the Poker Flat Rocket Launching Facility (PKR), and Fort Yukon, Alaska (FYU). The display occurred on Mar. 27, 1971, and the general morphology is described and discussed. It is suggested that fast auroral waves occur when a preceding substorm has enhanced the particle population in the region of the magnetosphere near L = 6 in the midnight sector; then transverse hydromagnetic waves, associated with the onset of further local substorm activity, become visible through their action on this enhanced particle population as they propagate inwards in the equatorial region.
Artificial auroral experiment by Aerobee rocketborne electron accelerator generated monoenergetic electron beam injection onto magnetospheric field
Ground based optical observation of raylike artificial auroras produced by rocket-borne accelerator generated electron beams, using image orthicon TV system
Auroral conjugacy observations over Alaska and south of New Zealand, noting correlation with geomagnetic field lines
Small scale spatially periodic auroral arc distortion observations, using low light level TV reception
Generation of artificial auroras by injecting electrons into upper atmosphere from Aerobee rocket-borne accelerator
Spatial and temporal conjugacy of visual auroras during magnetically quiet periods
Image intensifiers and orthicons, plumbicons, vidicons as photoelectric devices in TV auroral observation from ground stations and jet aircraft
HZ intensity variation in bright homogeneous auroras prior to and during breakup observed visually and with image orthicon TV systems
Image orthicon TV system, measuring auroral structure thickness
Polar magnetic disturbance activity and geomagnetic ring current growth relation noting small time lag
Latitudinal cross section of ionospheric current density profile of equatorial electrojet from rocketborne magnetometers
Image orthicon TV system and application to auroral observations, noting data acquisition mechanism
Nike-Apache rocket ionospheric current measurements using rubidium-vapor magnetometer