Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 17, 759-769, 1999
https://doi.org/10.1007/s00585-999-0759-0
© European Geosciences Union 1999
 
30 Jun 1999
ELF wave generation in the ionosphere using pulse modulated HF heating: initial tests of a technique for increasing ELF wave generation efficiency
R. Barr1, P. Stubbe2, and M. T. Rietveld3 1National Institute of Water and Atmospheric Research, PO Box 14901, Kilbirnie, Wellington, New Zealand, e-mail: r.barr@niwa.cri.nz
2Max-Planck-Institut für Aeronomie, D-37189, Katlenburg-Lindau, Germany
3EISCAT, Ramfjormoen, N-9020, Tromsdalen, Norway
Abstract. This paper describes the results of a preliminary study to determine the effective heating and cooling time constants of ionospheric currents in a simulated modulated HF heating, `beam painting' configuration. It has been found that even and odd harmonics of the fundamental ELF wave used to amplitude modulate the HF heater are sourced from different regions of the ionosphere which support significantly different heating and cooling time constants. The fundamental frequency and its odd harmonics are sourced in a region of the ionosphere where the heating and cooling time constants are about equal. The even harmonics on the other hand are sourced from regions of the ionosphere characterised by ratios of cooling to heating time constant greater than ten. It is thought that the even harmonics are sourced in the lower ionosphere (around 65 km) where the currents are much smaller than at the higher altitudes around 78 km where the currents at the fundamental frequency and odd harmonics maximise.

Key words. Electromagnetics (antennae) · Ionosphere (active experiments) · Radio science (non linear phenomena)


Citation: Barr, R., Stubbe, P., and Rietveld, M. T.: ELF wave generation in the ionosphere using pulse modulated HF heating: initial tests of a technique for increasing ELF wave generation efficiency, Ann. Geophys., 17, 759-769, https://doi.org/10.1007/s00585-999-0759-0, 1999.
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