Abstract
A study of nite Larmor radius (FLR) e ects on E B test particle chaotic transport in non-
monotonic zonal
ows with drift waves in magnetized plasmas is presented. Due to the non-
monotonicity of the zonal
ow, the Hamiltonian does not satisfy the twist condition. The electro-
static potential is modeled as a linear superposition of a zonal
ow and regular neutral modes of the
Hasegawa-Mima equation. FLR e ects are incorporated by gyro-averaging the EB Hamiltonian.
It is shown that there is a critical value the Larmor radius for which the zonal
ow transitions
from a pro le with one maximum to a pro le with two maxima and a minimum. This bifurcation
leads to the creation of additional shearless curves and resonances. The gyroaveraged nontwist
Hamiltonian exhibits complex patterns of separatrix reconnection. A change in the Larmor ra-
dius can lead to heteroclinic-homoclinic bifurcations and dipole formation. For Larmor radii for
which the zonal
ow has bifurcated, double heteroclinic-heteroclinic, homoclinic-homoclinic and
heteroclinic-homoclinic topologies are observed. It is also shown that chaotic transport is typically
reduced as the Larmor radius increases. Poincare sections shows that, for large enough Larmor
radius, chaos can be practically suppressed. In particular, small changes on the Larmor radius can
restore the shearless curve.
