  Longitudinal momentum spectra and electron drift directions are considered
for several laser wavelengths in Non-Sequential Double Ionization of helium
using three dimensional classical ensembles. In this model, the familiar
doublet for wavelength 800 nm and intensities of order 0.5 PW/cm^2, becomes a
triplet for wavelength 1314 nm, then a doublet with plateau for 2017 nm. The
results are explained based on whether the post-ionization impulse from the
laser results in backward drift for one or both electrons.
