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Abstract. A mechanism is proposed and evaluated for driving rotation in
tokamak plasmas by minority ion-cyclotron heating, even though this process
introduces negligible angular momentum. The mechanism has two elements:
First, angular momentum transport is governed by a diffusion equation with a
non-slip boundary condition at the separatrix. Second, Monte-Carlo
calculations show that energized particles will provide a torque density
source which has a zero volume integral but separated positive and negative
regions. With such a source, a solution of the diffusion equation predicts
the on-axis rotation frequency to be
= (4qmaxWJ*)eBR3a2ne(2
)2)-1(
/
)
where
| J*|
5 - 10 is a nondimensional rotation frequency
calculated by the Monte-Carlo ORBIT code. Overall, agreement with experiment
is good, when the resonance is on the low-field-side of the magnetic axis.
The rotation becomes more counter-current and reverses sign on the high
field side for a no-slip boundary. The velocity shear layer position is
controllable and of sufficient magnitude to affect microinstabilities.
IAEA 2001