Conical heat shield for electron emitting cathode

An electron emission cathode which includes a base, a heater connected to the base, an electron emitter connected to the heater at a mounting location distal to the base, and a conical heat shield surrounding a portion of the heater, having a truncated cone shape comprising a narrow end oriented toward the base and a wide end oriented toward the electron emitter. The conical heat shield is configured to reflect heat radiated by the heater toward the electron emitter. The conical heat shield reduces an overheating required to bring the electron emitter to an emission temperature and reduces a heating power required to operate the cathode.