A coil inductor for use with a LINAC is disclosed. The coil inductor comprises one or more tubes, wherein each tube comprises an interior support structure to strengthen the tubes. By supporting the tube, the amount of vibration is reduced, allowing the coil to resonate at its natural frequency. In some embodiments, the interior structure comprises one or more interior walls. These interior walls may be used to create a plurality of fluid channels that allow the flow of coolant through the tubes. An end cap may be disposed on the second end of the tubes to allow fluid communication between the supply fluid channels and the return fluid channels. The first ends of the one or more tubes may be connected to a manifold that includes a supply port and a return port for the passage of coolant.