Accession Number : ADP001448

Title :   Analysis of IPS (Interplanetary Scintillation) Data Using a Periodic Phase Screen Model for the Solar Wind,

Corporate Author : PHYSICAL RESEARCH LAB AHMEDABAD (INDIA)

Personal Author(s) : Basu,A. ; Alurkar,S. K.

Report Date : 27 DEC 1982

Pagination or Media Count : 15

Abstract : The intensity pattern obtained by diffraction from a periodic phase screen of finite dimensions has two distinct length scales: the width of the diffraction maxima and their interpeak distance. These can be uniquely by related to two length scales in the screen, namely the lateral extent of the screen and the phase period. In the weak scattering limit the autocorrelation and the Fourier transform of such a pattern are dominated by terms depending on the total size of the screen. We justify our assertion that the interplanetary medium (IPM) acts like a screen of finite lateral extent, and show that in this case the second moment of the power spectrum does not yield the desired information on irregularly sizes in the solar wind. This must be extracted from high-order terms, in particular from the dips in the power spectrum. The results of the present model and Salpeter's (1967) random phase screen model are compared with observations. The validity of the model as an idealization of the IPM is also examined. The values of irregularity size calculated from observations taken at Ahmedabad are a few hundred kilometres on the basis of this model. (Author)

Descriptors :   *Radio sources(Astronomy), *Scintillation, Patterns, Interplanetary space, Solar wind, Diffraction, Power spectra, Periodic variations, Autocorrelation, Fourier transformation, India

Distribution Statement : APPROVED FOR PUBLIC RELEASE