The theory of radio windows in the ionosphere and magnetosphere

Ray tracing analysis of L mode pumping of the ionosphere, with implications for the magnetic zenith effect

“…(Alternatively, complex raytracing might be useful; cf. Budden (1980).) Budden (1985, p. 489) gives a condition for the applicability of WKB in terms of the parameter q = ncosχ , which contains the refractive index, n = ck/ω, and the angle χ between k and B 0 .…”

Angular dependence of pump-induced bottomside and topside ionospheric plasma turbulence at EISCAT

“…Still assuming a horizontally stratified ionosphere, this remains true for a range of off-vertical angles of incidence up to the Spitze angle ( c ), defined as [Ginzburg, 1970;Budden, 1980]:…”

“…[3] In the high-latitude ionosphere, where a is small, an O mode wave launched at the critical incidence angle c will pass through the radio window [Budden, 1980] at the altitude where X = 1 without reflection and propagate in the Z mode [Ginzburg, 1970;Mjølhus, 1990]. Depending on the plasma density profile, upward propagation into denser plasma continues until either the ray is refracted downward, the Z mode reflection altitude is reached (i.e., X = 1 + Y), or until the plasma density decreases again (discussed below, see equation (6)) and the topside is reached (i.e., X = 1).…”

“…O mode to Z mode conversion in the radio window can be essentially 100% efficient [Ginzburg, 1970;Mjølhus and Flå, 1984] and therefore a small angular gap in the production of Langmuir waves around c can be expected for the bottomside ionosphere. Maximum transmission through the radio window is in the magnetic meridian plane [Budden, 1980], which is ∼2°west of the geographic meridian at EISCAT. This small offset is of no practical importance to the results described later.…”

A computer simulation study on the mode conversion process from slow X-mode to fast X-mode by the tunneling effect

“…Tang (1970) investigated a route of this type of mode conversion process analytically and showed the possibility of the indirect generation of fast Xmode waves from slow X-mode waves. In this process, however, a difficulty has been pointed out that, since the waves have to pass through the evanescent region (or layer) between the local upper-hybrid resonance frequency and the local fast X-mode cutoff frequency, the energy conversion rates have been thought to be very small compared with the other indirect processes, such as linear mode conversion to O-mode waves at the plasma frequency (Oya, 1971;Jones, 1977;Budden, 1980) and the nonlinear mode conversion processes (e.g., Roux and Pellat, 1979). Thus, the more direct processes to generate fast X-mode waves has Copy right c The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB.…”