  Asymmetric current sheets are likely to be prevalent in both astrophysical
and laboratory plasmas with complex three dimensional (3D) magnetic topologies.
This work presents kinematic analytical models for spine and fan reconnection
at a symmetric 3D null with asymmetric current sheets. Asymmetric fan
reconnection is characterized by an asymmetric reconnection of flux past each
spine line and a bulk flow of plasma across the null point. In contrast,
asymmetric spine reconnection is inherently equal and opposite in how flux is
reconnected across the fan plane. The higher modes of spine reconnection also
include localized wedges of vortical flux transport in each half of the fan. In
this situation, two definitions for reconnection rate become appropriate: a
local reconnection rate quantifying how much flux is genuinely reconnected
across the fan plane and a global rate associated with the net flux driven
across each semi-plane. Through a scaling analysis it is shown that when the
ohmic dissipation in the layer is assumed to be constant, the increase in the
local rate bleeds from the global rate as the sheet deformation is increased.
Both models suggest that asymmetry in the current sheet dimensions will have a
profound effect on the reconnection rate and manner of flux transport in
reconnection involving 3D nulls.
