Browsing by Author "Fejer, J.A."
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Item Open Access Beobachthung der Brillouin-Instabilitat in der Ionosphare(1974) Fejer, J.A.; Rinnert, K.; Woodman Pollitt, Ronald FranciscoObservations of weak stimulated Brillouin scattering with the 50 MHz incoherente scatter radar at Jicamarca are described. The non-linear interaction uf the upgoing radar wave with the downcoming waves, incoherently backscattered fromm greater heights, causes an asymmetry in the incoherent "ion" backscatter spectrum. For a given antenna aperture this asymmetry increases with increasing power and decreasing frequency of the rdar. The theoretically predicted effect was unambiguuosly verified, using 3 msec pulses and long integration time. Model calculations show good agreement with the observations.Item Restricted Detection of stimulated brillouin scattering by the Jicamarca Radar(American Geophysical Union, 1978-05-01) Fejer, J.A.; Rinnert, K.; Woodman Pollitt, Ronald FranciscoObservations of weak stimulated Brillouin scattering with the 50-MHz incoherent scatter radar at Jicamarca are described. The nonlinear interaction of the upgoing radar wave with the downcoming waves incoherently backscattered from greater heights, accuses an asymmetry in the incoherent 'ion' backscatter spectrum. For a given antenna aperture this asymmetry increases with increasing power and decreasing frequency of the radar. The theoretically predicted effect was unambiguously verified, using 3-ms pulses and long integration time. Model calculations based on the theory presented show good agreement with the observations.Item Restricted Observations of the HF-enhanced plasma line with a 46.8MHz radar and reinterpretation of previous observations with the 430 MHZ radar(American Geophysical Union, 1982) Fejer, J.A.; Ierkic, H.M.; Woodman Pollitt, Ronald Francisco; Röttger, J.; Sulzer, M.; Behnke, R.A.; Veldhuis, A.During 5.1 MHz HF transmissions below the F-region penetration frequency by a nearby ionospheric modification facility, radar echoes coming from F-region heights at a frequency of 46.8 + 5.1 = 51.9 MHz were received while a VHF radar using the 305 m spherical reflector at Arecibo was transmitting pulses coherently on 46.8 MHz. The bandwidth of the echoes was less than 10 Hz. The so-called decay line due to the parametric decay instability was expected at a frequency lower by about 300 Hz but it was not observed. Density variations caused by the ponderomotive force resulting from the standing wave pattern at 5. 1 MHz were tentatively invoked to explain the observations. Poorly understood aspects of previous analogous observations with the 430 MHz radar can be similarly explained.