Abstract: A high energy x-ray tube includes an evacuated chamber (12) containing a rotor (34) which rotates an anode (10) in the path of a stream of electrons (A) to generate an x-ray beam (B) and heat. The rotor includes an armature (36) which rotates around a stationary rotor support (40). An emissive coating is formed on the rotor by depositing an iron Fe.sub.3 O.sub.4 oxide plasma onto the surface of the armature. Heat generated in the anode during the production of x-rays is conducted through the anode and the rotor to the emissive coating which irradiates the heat across vacuum, thereby increasing the lifetime of the tube. A stator (32) generates an oscillating magnetic field which induces opposing fields in the Fe.sub.3 O.sub.4 coating to create the rotational forces to rotate the anode.