Dartmouth Events

Physics & Astronomy Space Plasma Seminar - Hassen Akbari - Boston University

Title: "Electron Beams and Langmuir Turbulence in High-Latitude Ionosphere"

Tuesday, October 15, 2013
Wilder 111
Intended Audience(s): Public
Categories: Lectures & Seminars

Abstract: Strong Langmuir turbulence and Langmuir collapse produced by beam-plasma interactions have beam observed over wide range of plasma parameters (over 23 orders of magnitude of plasma density and 4 orders of electron temperature) and huge ranges of wave and particle energy densities. They have been naturally produced in interplanetary medium by so called type-III electron beams and also in Earth’s foreshock by foreshock electron beams. Recently coherent echoes observed in incoherent scatter radar data in high-latitude ionosphere have proposed occurrence of Langmuir turbulence and wave collapse in limited heights close to ionospheric F-region peak. Large amplitude Langmuir waves associated with electron beams have also been observed in the auroral ionosphere by rockets and satellites for many years. Given the strong interaction of beams and plasma much can happen between the altitudes of the in-situ observations and altitude of radar observations. Therefore the main question regarding the ionospheric observations is evolution of the beam as it propagates down and its characteristics, i.e. beams density, beam energy, and beam’s velocity spread, at the altitude of observations. Results of 1D Zakharov simulation is employed to investigate the beam parameters that are required to produce Langmuir turbulence at the F-region heights. The results are compared with in-situ measurements of electron beams, electrostatic waves and electromagnetic emissions at higher altitudes in ionosphere.

For more information, contact:
Tressena Manning

Events are free and open to the public unless otherwise noted.