The possibility of increasing the service life of the sharp-focus X-ray source of the “transmission” type is studied. Available functional analogs of this device have a short service life (about 1000 h), a relatively low focusing level at a comparable power, and a high price. An increase in the service life up to 10000 h is reached by using a cathode assembly consisting of several parallel tungsten spiral filaments with a turn diameter of ∼0.1 mm, which are placed in the Wehnelt cylinder. Electrons are accelerated to the energy required for generation of X rays from the transmission-type anode (a metal foil with a thickness of ∼100 μm) by applying a voltage of 10–40 kV between the cathode and the anode.