Kiel 2011 – wissenschaftliches Programm
P 1.7: Vortrag
Montag, 28. März 2011, 18:10–18:25, HS H
Boundary effects in beam-plasma-instability experiments — •Christopher Rapson1, Olaf Grulke1,2, and Thomas Klinger1,2 — 1MPI for Plasma Physics, EURATOM Association, Greifswald — 2Ernst-Moritz-Arndt University, Greifswald
In a beam-plasma instability, the kinetic energy of the beam is converted to electrostatic or electromagnetic fluctuations. The growth rates are typically much higher than for collisional energy transfer. Beams play a dominant role in space plasmas, with the instabilities driving strong turbulence in the background plasma. Laboratory experiments can replicate these instabilities quite well, but are always restricted by boundary conditions and sheaths. Plasma sheaths are regions of strong density and potential gradients and may fluctuate due to causes which are unrelated to the beam. The beam properties are altered while passing through the sheath, before the beam reaches the homogeneous region of the plasma. In this talk, the sheath effects will be quantified for the special case of an ion acoustic beam-plasma instability. Results from Particle-In-Cell simulations - with and without boundaries - will be presented, along with experimental results obtained in a double plasma in the linear experiment VINETA.