Langmuir waves are known to be created upstream of planetary bow shocks by the two-stream instability driven by sunward-streaming particles. In this paper we examine Langmuir waves detected by Ulysses' Unified Radio and Plasma wave experiment (URAP) upstream of Jupiter. Wave envelopes qualitatively consistent with collapsed Langmuir waves are common in the Ulysses dataset, and while a few events have amplitudes exceeding the published theoretical thresholds for turbulent Langmuir wave collapse, the majority of events are too weak. Langmuir wave decay via backscattering within preexisting density fluctuations in the solar wind is examined as a mechanism capable of localizing Langmuir waves. Langmuir decay is found to be a viable process which may play a role in preparing plasma conditions for collapse, but cannot alone account for the observed data.
Bibliographical noteFunding Information:
.~(~l\r~on~k~~~~T~he/~ a,ut~hõr~s, ~thãñk.~ l.v cr I-1. Cairns of the University of towa for many detailed discussions and suggcs- lions which have accounted for signifcan( additions and ilt~pr~)v~rneIltõ st his study. Thanks to Rohcrt C. Stone for t~l~in~~ãintld~ a llowing us to take part in the I’~txsrs URAP investigation. Thanks to Naiguo Lin of the University of Minnesota. and Plttrick Canu ofCRPE,‘CNET for their hclpfui comments and suggestions.S amuel J. Bamc and John L. Phillips of Los Alamos National Laboratories were vory helpful in dis- cussions and providing SWOOPS data. This work was supported by NASA under contracl NAS5-3 IZIY.