LAGRANGIAN MAPPING APPROACH TO GENERATE INTERMITTENCY AND ITS APPLICATION IN PLASMA TURBULENCE

Abstract:

The Minimal Lagrangian Mapping procedure developed in the context of neutral fluid turbulence
(Rosales and Meneveau 2006) is a simple method to generate synthetic vector fields. Using a sequence
of low pass filtered fields, fluid particles are displaced at their rms-speed for some scale-dependent
time interval, and then interpolated back to a regular grid. Fields produced in this way are seen to
possess certain properties of real turbulence. We extend the technique to plasmas by taking
into account the coupling between the velocity and magnetic fields. We examine several possible
applications to plasma systems. One use is as initial conditions for simulations, wherein these synthetic
fields may efficiently produce a strongly intermittent cascade. The intermittency properties of the
synthetic fields are also compared with those of the solar wind. Finally, studies of cosmic ray transport
and modulation in the test particle approximation may benefit from improved realism in synthetic
fields produced in this way.