  In the classic Landau damping initial value problem, where a planar
electrostatic wave transfers energy and momentum to resonant electrons, a
recoil reaction occurs in the nonresonant particles to ensure momentum
conservation. To explain how net current can be driven in spite of this
conservation, the literature often appeals to mechanisms that transfer this
nonresonant recoil momentum to ions, which carry negligible current. However,
this explanation does not allow the transport of net charge across magnetic
field lines, precluding ExB rotation drive. Here, we show that in steady state,
this picture of current drive is incomplete. Using a simple Fresnel model of
the plasma, we show that for lower hybrid waves, the electromagnetic energy
flux (Poynting vector) and momentum flux (Maxwell stress tensor) associated
with the evanescent vacuum wave, become the Minkowski energy flux and momentum
flux in the plasma, and are ultimately transferred to resonant particles. Thus,
the torque delivered to the resonant particles is ultimately supplied by the
electromagnetic torque from the antenna, allowing the nonresonant recoil
response to vanish and rotation to be driven. We present a warm fluid model
that explains how this momentum conservation works out locally, via a Reynolds
stress that does not appear in the 1D initial value problem. This model is the
simplest that can capture both the nonresonant recoil reaction in the
initial-value problem, and the absence of a nonresonant recoil in the
steady-state boundary value problem, thus forbidding rotation drive in the
former while allowing it in the latter.
