Whistler waves, Langmuir waves and single loss cone electron distributions inside a magnetic cloud: Observations

Abstract

Whistler waves propagating along the ambient magnetic field are observed within a coronal mass ejection (on January 10, 1997) associated in time with Langmuir waves and electron distributions of a single loss cone type. In addition, background observations are made on the plasma wave activity in the sheath and foreshock regions that precede the magnetic cloud, on the observed radio emissions (including a type II radio burst) and on the geometry of the cloud. All the data comes from the WIND spacecraft. The whistler waves are identified using full magnetic waveforms while possible evidence of coexisting parallel, and antiparallel propagating Langmuir modes are found in the waveform and spectral wave data from the WAVES experiment. A few hundred low energy electron distributions from the Three‐Dimensional Plasma (3DP) experiment are investigated. Finally, we tentatively suggest that this type of plasma wave particle activity is linked to the type II emission observed, i.e., that the emission mechanisms are proceeding and taking place within the magnetic cloud instead of at the shock region as usually thought. The extra suprathermal electrons could source from electrons accelerated at reconnection sites between the magnetic cloud and the ambient interplanetary magnetic field. A linear instability study using observed properties of the electron distributions is to be presented in a following paper.