What is the middle coil of a microwave transformer for?

I need to know what the middle (approx 5 turn) coil of a microwave transformer is for, does it need to be there for the transformer to work properly and what difference will there be without it?
I am not going to reinstall this transformer in a microwave it has been modified to output 10KV to power a Tesla coil.

Its the heater supply for the Magnetron. Just leave it, it won't affect anything.

The MadScientist (author)  steveastrouk6 years ago
Does it matter if I remove it?
There was a massive performance improvement when I pulled out the shunts between the primary and secondary, 5KV improvement.
No, but you could use it to derive a nice 5 V supply for other stuff in there.