Split-beam studies of the effect of electron collisions on ISR spectra near k ⊥ B

Abstract

In an effort to test these models, we divided the Jicamarca radar into two beams, each with half the power and half the antenna of the full system, and ran the standard double pulse Faraday/ ACF mode that gives ACFs in the F region. With split beams each beam has only one quarter of the signal-to-noise ratio of the full system, but it allows us to measure at two different aspect angles simultaneously. We have made comparisons between three pointing directions, which at an altitude of 400 km differ from normal to B by 4.8º, 3.4º, and 2.0°. (We compared 4.8 with 3.4 degrees and then with 2.0 degrees.) These angles ali vary slightly with altitude and are significantly smaller than they were when Jicamarca was built because of the slow change in the geomagnetic field. (These beam positions once were called the 6, 4.5, and 3 degree (on axis) positions.)