Abstract: An inductive device can heat a body having a slender bore, with an inductor assembly that includes a coolant system. The assembly has a parallel pair of elongate inductors sized to fit deep inside the bore. Each of these inductors has a distal end and a proximal end. The distal ends of the inductors can be electrically interconnected. These inductors are adapted at their proximal ends to connect to a source of current for circulating current along the inductors. The coolant system is adapted to communicate with a source of coolant to circulate coolant along the inductors. The inductors are inserted through the bore of the body to lie lengthwise, without coiling, along the length of the bore. Coolant can then be pumped along the elongate inductors. Then by driving alternating current to flow through the inductors, magnetic coupling to the body occurs to produce heating effects.