lipo batt

I am pulsing a 38mH coil (16 AWG wire wrapped around a small tube) with a IRFB4115pbf MOSFET at 66.6v (3 lipo 5200mAH "50C" battery's in series). It's a lot of juice! Using Lt spice I simulated this and found that the voltage spikes can reach up to 20kv. I am trying to figure out if I should use...