How to define the current density integral constraint on the surface of a conductor?

Hi everyone,

I want to simulate a superconducting coil, but I only know how to set E-J character.

I don't konw how to add a current in the superconduct. The literature use I=integrate(J) to

constraint the edge of the superconduct.

So how to define the current density integral constraint on the surface of a conductor?

Any suggestion you make will help me. Thanks for reading this.