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Effects of interplanetary shocks on kilometric type III radio bursts
Author(s) -
MacDowall R. J.
Publication year - 1989
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl016i008p00923
Subject(s) - physics , interplanetary spaceflight , intensity (physics) , astrophysics , shock (circulatory) , electron , solar wind , cutoff , computational physics , plasma , optics , nuclear physics , medicine , quantum mechanics
Interplanetary (IP) type III bursts that undergo sudden intensity changes when their electron beams traverse the vicinity of an IP shock are examined. Three types of intensity changes are discussed: cutoffs in which the type III intensity is abruptly reduced and remains at the reduced level for all lower frequencies, narrow‐band intensifications that frequently occur on the high‐frequency edge of a cutoff, and narrow‐band intensity reductions. Pitch angle scattering of the beam electrons in the enhanced magnetic turbulence downstream of shocks is proposed as a principal cause of the intensity cutoffs and, possibly, the intensifications. These observations suggest that one type III emission mode (f P or 2f P ) is frequently at least 10 times more intense than the other mode.