1 research outputs found
Toroidal momentum transport in a tokamak caused by symmetry breaking parallel derivatives
A new mechanism for toroidal momentum transport in a tokamak is investigated
using the gyro-kinetic model. First, an analytic model is developed through the
use of the ballooning transform. The terms that generate the momentum transport
are then connected with the poloidal derivative of the ballooning envelope,
which are one order smaller in the normalised Larmor radius, compared with the
derivative of the eikonal. The mechanism, therefore, does not introduce an
inhomogeneity in the radial direction, in contrast with the effect of profile
shearing. Numerical simulations of the linear ion temperature gradient mode
with adiabatic electrons, retaining the finite rho* effects in the ExB
velocity, the drift, and the gyro-average, are presented. The momentum flux is
found to be linear in the normalised Larmor radius (\rho*) but is,
nevertheless, generating a sizeable counter-current rotation. The total
momentum flux scales linear with the aspect ratio of the considered magnetic
surface, and increases with increasing magnetic shear, safety factor, and
density and temperature gradients