  Edge localized modes (ELMs) are instabilities at the tokamak edge that can
have short outbursts of highly energetic particles and heat, which can severely
damage the walls of a plasma reactor. Resonant magnetic perturbations (RMPs)
are used to mitigate or eliminate ELMs from the plasma. One effect that can
reduce the intensity of the RMP is screening, which is caused by eddy currents
in conducting structures or a plasma that are induced by a time-varying
magnetic field. The eddy current code CARIDDI was recently coupled with the
magnetohydrodynamics (MHD) code JOREK, and is able to capture the behavior of
volumetric conducting structures that surround a plasma. The objective of this
study is to characterize screening behavior in the JOREK-CARIDDI coupling.
  The analysis is divided in three parts. First, CARIDDI results are
benchmarked against results from STARWALL, another JOREK extension that
captures interactions of (two-dimensional) conducting structures. It is found
that CARIDDI and STARWALL show good agreement, with slight variations. The
second part covers the screening of time-varying RMP fields by conducting
structures, oscillating at frequencies from 3 Hz to 10 kHz. The overall trends
in screening behavior align qualitatively with findings from a previous
analysis. However, an additional contribution to the screening at frequencies
above 1 kHz was not observed, because the simulation in this report does not
include screening by the RMP coil casing. Finally, a few tests were performed
using a plasma configuration, to study the effect of plasma screening,
including realistic plasma background flows. The results demonstrated the
induction of eddy currents at rational surfaces within the plasma. These
results contribute to an improved understanding of the screening of RMP fields,
which is relevant for several applications to the operation of fusion reactors.
