  The flux-injection hypothesis for driving coronal mass ejections (CMEs)
requires the transport of substantial magnetic energy and helicity flux through
the photosphere concomitant with the eruption. Under the magnetohydrodynamics
approximation, these fluxes are produced by twisting magnetic field and/or flux
emergence in the photosphere. A CME trajectory, observed 2000 September 12 and
fitted with a flux-rope model constrains energy and helicity budgets for
testing the flux-injection hypothesis. Optimal velocity profiles for several
driving scenarios are estimated by minimizing the photospheric plasma
velocities for a cylindrically symmetric flux-rope magnetic field subject to
the flux budgets required by the flux-rope model. Ideal flux injection,
involving only flux emergence, requires hypersonic upflows in excess of the
solar escape velocity 617 km/s over an area of 6x10^8 km^2 to satisfy the
energy and helicity budgets of the flux-rope model. These estimates are
compared with magnetic field and Doppler measurements from Solar Heliospheric
Observatory/Michelson Doppler Imager on 2000 September 12 at the footpoints of
the CME. The observed Doppler signatures are insufficient to account for the
required energy and helicity budgets of the flux-injection hypothesis.
