  We present a detailed characterization of the structure and evolution of
differentially rotating plasmas driven on the MAGPIE pulsed-power generator
(1.4 MA peak current, 240 ns rise-time). The experiments were designed to
simulate physics relevant to accretion discs and jets on laboratory scales. A
cylindrical aluminium wire array Z pinch enclosed by return posts with an
overall azimuthal off-set angle was driven to produce ablation plasma flows
that propagate inwards in a slightly off-radial trajectory, injecting mass,
angular momentum, and confining ram pressure to a rotating plasma column on the
axis. However, the plasma is free to expand axially, forming a collimated,
differentially rotating axial jet that propagates at $\approx 100$ km/s. The
density profile of the jet corresponds to a dense shell surrounding a
low-density core, which is consistent with the centrifugal barrier effect being
sustained along the jet's propagation. We show analytically that, as the
rotating plasma accretes mass, conservation of mass and momentum implies plasma
radial growth scaling as $r \propto t^{1/3}$. As the characteristic moment of
inertia increases, the rotation velocity is predicted to decrease and settle on
a characteristic value $\approx 20$ km/s. We find that both predictions are in
agreement with Thomson scattering and optical self-emission imaging
measurements.
