Abstract: The invention is a method for controlling the temperature of a primary heat-generating source in an environment whose temperature may vary widely. A heat-pipe is used to carry the heat from the source to a sink at ambient temperature. A separate control source applies heat to the heat pipe. The condensed liquid returning in the heat pipe is partly evaporated by the control heat, whereby the flow of liquid available for evaporation by the primary heat source is reduced and the heat conducted away from the source by the pipe is consequently reduced. The control source heat is regulated by a servo circuit to maintain the temperature of the primary source. The efficiency is higher than prior-art controllers using a constant thermal impedance between source and sink.

Abstract: 2. In a reflex klystron tube apparatus, means for forming a beam of electrons, a resonator means positioned along the beam path, said resonator means being apertured for the passage of the beam of electrons therethrough for electromagnetic coupling to the beam, reflector means disposed on the side of the resonator remote from said means for forming the beam of electrons, said reflector means serving for reflecting the electrons incident upon the reflecting fields of said reflector means back through said resonator means substantially along the incident beam path, said means for reflecting the electrons formed and arranged to impart a slight transverse velocity to the electrons whereby they are caused to move transversely of and out of the beam in a small number of beam transits thereby minimizing unwanted amplitude and power modulation in the output signal of the tube apparatus.