Accession Number : AD0634358

Title :   NEGATIVE ION DETECTION IN THE IONOSPHERE FROM EFFECTS ON ELF WAVES.

Descriptive Note : Research rept. Jul 65-Mar 66,

Corporate Author : IOWA UNIV IOWA CITY DEPT OF PHYSICS AND ASTRONOMY

Personal Author(s) : Shawhan, Stanley D.

Report Date : MAR 1966

Pagination or Media Count : 54

Abstract : The theory for propagation of small amplitude electromagnetic waves in a cold, homogeneous plasma including negative ions and immersed in a uniform, static magnetic field is developed. It is found that for longitudinal propagation each negative ion introduces a resonance at the negative in gyrofrequency, a concentration dependent cutoff frequency above the negative ion gyrofrequency, and possibly a crossover frequency depending on the ion concentrations and charge to mass ratios. At both the gyrofrequency and the cutoff frequency the group refractive index becomes infinite. Between these two frequencies there is a 'nose' frequency for which the group refractive index is a minimum. Examples are given for a three and five component plasma. Application of this negative ion theory is made to propagation of negative ion whistlers in the ionosphere. It is found that for frequencies near the negative ion gyrofrequencies the WKB approximation is valid above 300 KM during the nighttime and 150 KM during the daytime. Effects of collisions can be neglected above 150 KM. An ideal experiment is proposed for observation of negative ion whistlers (1-1000 cps). Sample whistler, frequency-time spectrograms like those which would be observed with such an experiment are sketched. From the distinctive frequencies on these sample spectrograms, it is shown that the negative ion specie and concentration can be determined using the developed cold plasma expressions. (Author)

Descriptors :   (*ELECTROMAGNETIC RADIATION, *IONOSPHERIC PROPAGATION), (*IONS, ATMOSPHERICS), (*ATMOSPHERICS, MAGNETOHYDRODYNAMICS), VERY LOW FREQUENCY, WAVE PROPAGATION, MAGNETOOPTICS, REFRACTIVE INDEX, PLASMAS(PHYSICS), ATMOSPHERIC SOUNDING

Subject Categories : Atmospheric Physics
      Plasma Physics and Magnetohydrodynamics
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE