I don't believe this would happen. Sure, there's hydrogen in the atmosphere, but it's bonded and stable. The rest of the relatively insulating materials would quickly smother the reaction. The sun's advantage is that its entire mass is fusion-ready, it's isolated, and the sheer gravitational force generated by it sustains its reaction.
Still, I see your point. I would suggest instead different grades of coil. The first grade being much easier to make, and requiring only eight of them, to completely surround the reactor. The lower grade coils would be components of higher grade coils. Varying effectiveness is achieved through a combination of coil grade and coil size.
Actually I like the idea of potentially turning your base into a searing ball of plasma unless you control it, some sort of percentage based chance depending on how many coils you have in place would be fun.