A cathode assembly for emitting charged particles, used in for example an electron gun as source for generating an electron beam is provided. The cathode assembly has a cathode including an emitting member and a carrier. The emitting member is mounted in the carrier, and the carrier is electrically connected to a holder. The cathode is heated by irradiation from an external source, whereby the emitting member emits charged particles from an emitting surface at an emitting temperature. The connection between the carrier and the holder provides a thermal barrier for reducing the amount of thermal energy transferred from the cathode to the holder.