A cathode-ray tube having an electron gun includes at least one cathode assembly comprising a tubular cathode sleeve, a heater filament disposed within the sleeve and a novel cathode eyelet coaxially surrounding at least a portion of the cathode sleeve and attached thereto. The cathode sleeve has oppositely disposed ends, one end being open and the other end being closed by a cap having an electron emitting coating thereon. The novel eyelet comprises a laminated bimetal member including a support layer and an emissivity modifying layer. The support layer has a distal end, a proximal end and a central portion therebetween. The proximal end of the support layer is attached to the open end of the cathode sleeve. The emissivity modifying layer is disposed on at least a portion of the interior surface of the central portion of the support layer to reduce radiation loss from the cathode sleeve and cap. The emissivity modifying layer is spaced from the proximal end of the support layer by a heat dam which reduces conduction loss up the eyelet. A method of altering the thermal characteristics of the cathode assembly is also disclosed.