INTERACTION OF RING CURRENT AND RADIATION BELT PROTONS WITH DUCTED PLASMASPHERIC HISS .1. DIFFUSION-COEFFICIENTS AND TIMESCALES

Protons that are convected into the inner magnetosphere in response to enhanced magnetic activity can resonate with ducted plasmaspheric his s in the outer plasmasphere via an anomalous Doppler-shifted cyclotron resonance. Plasmaspheric hiss is a right-hand-polarized electromagnet ic emission that is observed to fill the plasmasphere on a routine bas is. When plasmaspheric hiss is confined within field-aligned ducts or guided along density gradients, wave normal angles remain largely belo w 45-degrees. This allows resonant interactions with ions at typical r ing current and radiation belt energies to take place. Such field-alig ned ducts have been observed both within the plasmasphere (Kozyra et a l., 1987a; Koons, 1989) and in regions outside of the plasmasphere (Ch an and Holzer, 1976). Wave intensities are estimated using statistical information from studies of detached plasma regions (Chan et al., 197 4). Diffusion coefficients are presented for a range of L shells and p roton energies for a fixed wave distribution. Harmonic resonances in t he range n = +/- 100 are considered in order to include interactions b etween hiss at 100 Hz to 2 kHz frequencies, and protons in the energy range between approximately 10 keV and 1000 keV. Diffusion timescales are estimated to be of the order of tens of days and comparable to or shorter than lifetimes for Coulomb decay and charge exchange losses ov er most of the energy and spatial ranges of interest.