When the Particle release specification is set to 
Specify current, the 
Current Density subnode is available from the context menu (right-click the 
Wall parent node) or from the 
Physics toolbar, 
Attributes menu. The 
Current Density subnode uses accumulated variables on each boundary element in the selection of the parent node to calculate the current density due to the impact of charged particles.
 
    Select a Type: 
Current density or 
Normal current density. For 
Current density accumulated variables are defined for the components of the current density vector. For 
Normal current density one accumulated variable is defined for the normal current density in each boundary element.