An apparatus and method for cooling an exhaust gas flow of an internal combustion engine of a truck or other vehicle includes a conduit connected to an air source, for example, a turbo driven compressor to deliver air to the exhaust stack or tail pipe. The electron gun contains at least two focus electrodes receiving a fixed focus voltage, and the focus electrodes are arranged in a row in the electron gun. The host includes a plurality of sets of ID indication pins and an ID set pin, and each controller electrically connects with and controls a pair of IDE devices.