Ih. Cairns, DETECTABILITY OF ELECTROSTATIC DECAY PRODUCTS IN ULYSSES AND GALILEO OBSERVATIONS OF TYPE-III SOLAR RADIO-SOURCES, The Astrophysical journal, 449(1), 1995, pp. 95-98
Recent in situ Ulysses and Galileo observations of the source regions
of type III solar radio bursts appear to show an absence of ion acoust
ic waves S produced by nonlinear Langmuir wave processes such as the e
lectrostatic (ES) decay, in contradiction with earlier ISEE 3 observat
ions and analytic theory. This Letter resolves these apparent contradi
ctions. Refined analyses of the maximum S-wave electric fields produce
d by ES decay and of the characteristics of the Ulysses Wave Form Anal
yzer (WFA) instrument show that the bursty S waves observed by ISEE 3
should be essentially undetectable by the Ulysses WFA. It is also show
n that the maximum S-wave levels predicted for the Galileo event are l
ess than or similar to the instrumental noise level, thereby confirmin
g an earlier suggestion. Thus, no contradictions exist between the ISE
E 3 and Ulysses/Galileo observations, and no evidence exists against E
S decay in the published Ulysses and Galileo data. All available data
are consistent with, or at worst not inconsistent with, the ES decay p
roceeding and being the dominant nonlinear process in type III bursts.