Effects of orbit squeezing on poloidal mass flow and bootstrap current in tokamak plasmas

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Abstract
It is shown, by solving the drift kinetic equation, that the asymptotic values of the poloidal mass flow and the bootstrap current in the banana regime of large‐aspect‐ratio tokamak plasmas are not affected by orbit squeezing. However, because the definition of ion collisionality υ*i is reduced by a factor S−3/2, with S=1−(ρpid ln Er/dr) (cEr/Bpνti), the values of both the poloidal mass flow and the bootstrap current at the banana–plateau transition are different from those of the conventional neoclassical theory. Here, ρpi is the ion poloidal gyroradius, Er is the radial electric field, c is the speed of light, Bp is the poloidal magnetic strength, νti is the ion thermal speed, and r is the local radius. The implications for the experimental observations of poloidal rotation speeds in high mode (H mode) are discussed.