Heliospheric Langmuir wave observations from the Ulysses spacecraft Original Research Article

Langmuir waves are electrostatic plasma oscillations produced by unstable electron beams in the solar wind and elsewhere. Typical electron sources are solar flares, shocks, and magnetic holes. In this paper, we present an overview of the Langmuir waves observed by Ulysses during both its solar minimum and solar maximum orbits. Langmuir waves in magnetic holes are a major component of the total Langmuir wave population; they occur preferentially in fast solar wind and are observed by Ulysses to be most intense within 2 AU of the Sun.