A generation mechanism for the frequency up-shifted plasma lines observed in the Tromso´s HF heating experiments

Summary form only given. A new spectral feature in the backscattering spectrum of EIS CAT 933 MHz radar was observed throughout most of the observing period of the heating experiments performed with O-mode heater transmitting near Tromso, Norway on August 16-18, 1986. The radar returns were enhanced at frequencies offset from the radar frequency by a frequency a few hundred KHz more than the heater frequency of 4.04 MHz [Isham et al., 1990]. Thus, a different physical mechanism is considered in the present work for explaining the Tromso´s observations. It is the parametric decay of a right handed circularly polarized pump wave (0-mode) into a whistler wave (decay mode) and a frequency upshifted Langmuir wave (sideband). Since the frequency of whistler wave extends to the range of a few hundred kHz, the frequency of the exited Langmuir wave agrees with that of the experimental observation.