Neoclassical orbits are affected by spatially and temporally varying radial electric field in a tokamak.
For the case of spatially varying electric field, high electric field shear causes a dramatic change of particle orbit topology.
In other words, the trajectories of the particles can be squeezed or expanded. Squeezing (or expanding) factor is well-represential by
$S\equiv 1+(eI^2 /m Ω^2 ) Φ˝$, where Ω = eB/m, I=BR, and Φ˝ =d^2 Φ /d{ φ }^2 $ is the electric field shear.
On the other hand, for the case of temporally varying electric field, there is no known analytic representation of the orbit modification. In this work, a detailed numerical investigation of the neoclassical polarization drift phenomenon is presented, which may lead to a useful analytic formula in the future.
