The External Current Density node adds an externally generated current density 
Je, which appears in Ohm’s law
 
    The external current density does not contribute to the losses (due to Joule heating), since there is no electric field associated with it. To include the contribution to the losses from the external current density, select the Add contribution of the external current density to the losses check box. Then select an option from the 
External losses list — 
From domain conductivity (the default) or 
User defined. If 
From domain conductivity is selected, the heat source is computed using the conductivity specified in the material model feature (such as 
Current Conservation) that is applied in the domain. For 
User defined, enter a value for 
Qe (SI unit: W/m
3) to specify a user-defined heat source.
 
    Add a contribution as a Harmonic Perturbation by right-clicking the parent node or clicking 
Harmonic Perturbation on the 
Physics toolbar. For more information see 
Harmonic Perturbation — Exclusive and Contributing Nodes.
 
    Based on space dimension, enter the coordinates (x, 
y, and 
z for 3D components, for example) of the 
External current density Je (SI unit: A/m
2). The defaults are 0 A/m
2.