ON THE ORIGIN OF MICROPULSATIONS
Abstract
A unifying theory of the origin of micropulsations that depends for its acceptance on cavity resonances of hydromagnetic waves is presented. Following recent developments in the literature, two cavities are postulated. The outer cavity is bounded by the magnetospheric surface and the Alfven wave velocity inversion at a height of about 2000 km. The inner cavity is bounded by Alfven wave velocity inversion at 2000 km and the top of the ionosphere. The Q of either cavity is postulated to be longitude dependent, being influenced by the diurnal variation in the absorption of the walls. Alternatively, the efficiency of the mechanism for transferring energy from the solar plasma to the magnetosphere may be longitude dependent. In either event damped oscillations occur in the daytime hemisphere. Triggering of cavity oscillations in the daytime hemisphere may be achieved through minor random fluctuations in the solar plasma. In contrast, a marked step function increase in solar plasma velocity is considered necessary to trigger oscillations in the nighttime hemisphere. The basic excitation for all pulsations is GMT dependent, but the efficiency of the triggering mechanism is LMT dependent. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1962
- Accession Number
- AD0290307
Entities
People
- Stanley H. Ward
Organizations
- University of California, Berkeley