Induction heating apparatus for use in causing necrosis of neoplasm

Claim 1

An induction heating apparatus having an induction heating coil and a power supply means connected to said heating coil for supplying electric power to said coil in which the improvement comprises: a plurality of different coils which are identical to said heating coil, each of said coils being a flat "pancake" coil including a series of turns of an electrically non-conductive tube with a multi-strand conductor extending through its interior, this conductor being sufficiently small so as to permit a cooling fluid to be circulated through the interior of the tube within which it is located, said coils being located closely adjacent to one another in a "stack" in which said coils are aligned with one another so as to be capable of serving as a series of closely coupled transformer coils, manifold means connected to the ends of said tubes of said coils for conveying a cooling fluid through said tubes of said coils, a capacitor means connected across the ends of the conductor in each of said coils and said heating coil so as to constitute, in combination with the coil to which it is attached, a tank circuit having a resonant frequency, said capacitor means all having equal capacitance values, said tank circuits all having the same resonant frequency, said power supply means being connected only to said heating coil and the tank circuit associated with said heating coil and capable of supplying power at a frequency which is the same as the resonant frequency of the tank circuits, said power supply means being adjustable so that the frequency of the power supplied to the tank circuit to which it is connected can be adjusted in accordance with any change in the resonant frequency of said tank circuits.