  I present a scenario by which an accretion flow with alternating angular
momentum sense on to a newly born neutron star in core collapse supernovae
(CCSNe) efficiently amplifies magnetic fields and by that launches jets. The
accretion flow of a collapsing core on to the newly born neutron star suffers
the spiral standing accretion shock instability (SASI). This instability leads
to a stochastically variable angular momentum of the accreted gas, that in turn
forms an accretion flow with alternating directions of the angular momentum,
hence alternating shear, at any given time. I study the shear in this
alternating-shear sub-Keplerian inflow in published simulations, and present a
new comparison with Keplerian accretion disks. From that comparison I argue
that it might be as efficient as Keplerian accretion disks in amplifying
magnetic fields by a dynamo. I suggest that although the average specific
angular momentum of the accretion flow is small, namely, sub-Keplerian, this
alternating-shear accretion flow can launch jets with varying directions,
namely, jittering jets. Neutrino heating is an important ingredients in further
energizing the jets. The jittering jets locally revive the stalled accretion
shock in the momentarily polar directions, and by that they explode the star. I
repeat again my call for a paradigm shift from a neutrino-driven explosion of
CCSNe to a jet-driven explosion mechanism that is aided by neutrino heating.
