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Full-Text Articles in Physical Sciences and Mathematics
Experiments On The Attenuation Of Third Sound In Saturated Superfluid Helium Films, Robert Hallock, K. L. Telschow, R. K. Galkiewicz
Experiments On The Attenuation Of Third Sound In Saturated Superfluid Helium Films, Robert Hallock, K. L. Telschow, R. K. Galkiewicz
Robert Hallock
Upper limits of the attenuation of third sound in saturated superfluid 4He films have been measured in three separate experiments. Our observations at frequencies from 0.1 to 200 Hz indicate that the attenuation in these thick films is substantially lower than would be inferred from the only previous experiment done on saturated films. We observe the third-sound velocity to have the temperature dependence predicted by Bergman.
Radar Observations Of Two Dimensional Turbulence In The Equatorial Electrojet, 2, Bela G. Fejer, D. T. Farley, B. B. Balsley, R. F. Woodman
Radar Observations Of Two Dimensional Turbulence In The Equatorial Electrojet, 2, Bela G. Fejer, D. T. Farley, B. B. Balsley, R. F. Woodman
Bela G. Fejer
Observations with an altitude resolution of about 1 km were made with the large, vertically directed 50-MHz radar system at the Jicamarca Radar Observatory during the day, when the electrojet was strong. Type 1 (‘two stream’) echoes were seen in a limited range of altitudes, with Doppler shifts corresponding to upward and downward motion at the acoustic velocity. Most of the radar returns were due to type 2 echoes, however. The direction of motion of the type 1 waves sometimes reversed in as little as 1 s, supporting a turbulent model of the electrojet region. During the day the upgoing …
Radar Measurements Of Neutral Winds And Temperatures In The Equatorial E Region, B. B. Balsley, Bela G. Fejer, D. T. Farley, R. F. Woodman
Radar Measurements Of Neutral Winds And Temperatures In The Equatorial E Region, B. B. Balsley, Bela G. Fejer, D. T. Farley, R. F. Woodman
Bela G. Fejer
The phase velocity of type 1 irregularities in the equatorial electrojet, which can be easily measured by radar, depends upon both the ion acoustic velocity (and hence the temperature) in the medium and the neutral wind velocity. By measuring the phase velocity at several zenith angles both of these quantities in principle can be determined. This note describes the technique and its limitations and presents a few preliminary results obtained at 50 MHz at the Jicamarca Radar Observatory in Peru. These results show E region east-west wind velocities as large as 100 m/s, temperature variations of greater than 100°K, and …
Radar Studies Of Anomalousvelocity Reversals In The Equatorial Ionosphere, Bela G. Fejer, D. T. Farley, B. B. Balsley, R. F. Woodman
Radar Studies Of Anomalousvelocity Reversals In The Equatorial Ionosphere, Bela G. Fejer, D. T. Farley, B. B. Balsley, R. F. Woodman
Bela G. Fejer
Radar observations made at Jicamarca show that the equatorial electrojet current and the E and F region electric fields can reverse from their normal direction during the day or night and during magnetically quiet or disturbed conditions. The nighttime reversals can only be detected by such radar measurements. The observations support most of the current hypotheses concerning the electrojet plasma instabilities. The rapid reversals sometimes seen during disturbed conditions indicate that high-latitude currents and electric fields associated with substorm activity strongly perturb the dynamo current system at all latitudes.