کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1777729 | 1021756 | 2008 | 7 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Eigenmode analysis of pitch-angle diffusion of energetic electrons in the outer zone Eigenmode analysis of pitch-angle diffusion of energetic electrons in the outer zone](/preview/png/1777729.png)
We demonstrate a new method of analyzing observed storm-time pitch-angle distributions to obtain information regarding the appropriate choice of the pitch-angle diffusion coefficients. We apply this method to MeV electrons in the outer zone as a diagnostic of the relative contribution of electromagnetic ion-cyclotron (EMIC) waves and whistler-mode hiss and chorus. We assume EMIC and hiss are confined to a plasmaspheric plume (hence, “plume waves”), with chorus prevalent over large portions of the day and night side. First, we determine the eigenmodes and eigenvalues of the pitch-angle diffusion operator predicted by quasilinear diffusion theory and approximate chorus, hiss, or EMIC plasma wave parameters for energetic electrons in the outer zone. Then, by projecting pitch-angle distributions observed by CRRES into the eigenmodes, we determine whether the pitch-angle distributions are consistent with the assumed diffusion process for various relative weighting of chorus and plume waves. Eigenmodes with shorter decay times (i.e., larger negative eigenvalues) ought to represent a comparatively smaller portion of the total flux in the pitch-angle distribution. We show that several observed pitch-angle distributions are consistent with predominantly chorus-driven pitch-angle diffusion, with at most a minor contribution from plume waves.
Journal: Journal of Atmospheric and Solar-Terrestrial Physics - Volume 70, Issue 14, November 2008, Pages 1738–1744