It can be used as a power supply for the tesla coil or it can be used as an inductin heater ( for the induction heater try a 300v with 1uF or higher) ...
Everybody who is interested in high voltage herd about the zvs driver for the flyback transformer.
2x IRFP250 n-fet
2x 12v zenner diodes
2x 470ohm resistors
2x 10kohm resistors
2x 400v fast diodes
1x inductor 200uH
1x 250v capacitor 0.68uF or higher