Abstract:
We report an experimental study of a dilute ``gas'' of magnetic
particles subjected to a vertical alternating magnetic field in
a 3D container. Due to the torque exerted by the field on the
magnetic moment of each particle, a spatially homogeneous and
random forcing is reached where only rotational motions are
driven. This forcing differs significantly from boundary-driven
systems used in most previous experimental studies on non
equilibrium dissipative granular gases. Here, no cluster
formation occurs, and the equation of state displays strong
analogy with the usual gas one apart from a geometric factor.
These observations and the measurement of collision statistics
at a container wall are well explained by a simple model, and
enable to better understand out-of-equilibrium systems uniformly
``heated''.
45.70.-n Granular systems
05.20.Dd Kinetic theory
75.50.-y Studies of specific magnetic materials