Abstract
Abstract. Ducted propagation of whistler waves in the terrestrial magnetosphere-ionosphere system was discussed and studied long before the first in-situ spacecraft measurements. While a number of implicit examples of the existence of ducted propagation have been found, direct observation of ducts has been hampered by the low sampling rates of measurements of the plasma density. The present paper is based on Cluster observations of chorus waves. The ability to use measurements of the spacecraft potential as a proxy for high time resolution electron density measurements is exploited to identify a number of cases when increased chorus wave power, observed within the radiation belts, is observed simultaneously with density enchantments. It is argued that the observation of ducted propagation of chorus implies modification of numerical models for plasma-wave interactions within the radiation belts.
Highlights
Electron acceleration in the radiation belt is one of the unsolved problems of magnetospheric physics that has important implications for the security of many modern technological systems that rely on spacecraft operating at geosynchronous orbit
Many numerical models of the electron dynamics within the radiation belts are developed to investigate the interaction between chorus type waves and energetic electrons (Ni et al, 2011)
In the present paper we have reported cases when observation of increased chorus wave power in the low frequency band coincide with density crests as indicated by measurements of the spacecraft potential
Summary
Electron acceleration in the radiation belt is one of the unsolved problems of magnetospheric physics that has important implications for the security of many modern technological systems that rely on spacecraft operating at geosynchronous orbit. Cluster data have been used to show that the propagation of a significant number of chorus wave packets is oblique to the magnetic field (Santolık et al, 2009). This oblique propagation possess another problem for numerical models based on quasilinear diffusion. In case of oblique propagation the wave packet will leave a particular field line This limits the number of times a wave packet can interact with particles on a particular field line and in the best case makes justification of the random phase approximation much more difficult. In the present paper we exploit the use of the Cluster spacecraft potential as a high time resolution proxy measurement of the plasma density to provide information about changes in the plasma density that prove the existence of the ducted regime of propagation of chorus waves
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