Magnetic induction for a tesla flat spiral coil

Telemachus

Hi there. I have a current I running throught a tesla spiral coil, and I have to compute the magnetic field at the center of it. The tesla coil has N turns, and an inner radius a, and outer radius b.

This is the tesla spiral coil:

The courrent enters through the outer cable, and goes out through the inner one.

I'm not sure on how to treat this problem. Should I consider the spiral coil as a flat disk with the courrent flowing from the outside to the inside?