Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.79: Poster

Donnerstag, 11. März 2004, 16:00–18:00, Poster D

Differences of the magnetic susceptibility in alternating and rotating fields — •Robert Krauß, Reinhard Richter, and Ingo Rehberg — Experimentalphysik V, 95440 Bayreuth

Considering a layer of ferrofluid set in motion by a rotating magnetic field raises the question how the velocity depends on the frequency of the field. Investigations and calculations on this effect (referred to as magnetic pumping) yield that the velocity is a function of the real and imaginary parts of the complex magnetic susceptibility. In a first approach the susceptibility was measured in a toroidal channel with a linear alternating field. We found substantial differences between the measured velocity and the one calculated from the complex susceptibility. However taking into account the complex susceptibility measured in a rotating field, leads to a better understanding of the fluid motion. The ferrofluid applied shows a strong coupling parameter of λ ≈ 3. This fact indicates that aggregates in the fluid exist and are responsible for the non-linear behaviour obtained.