A 3.2 millimeter high power magnetron

This paper describes a 3.2 mm wavelength, rising sun cavity, pulse magnetron capable of delivering up to 10 kw peak rf power at pulse widths between 5 and 200 nanoseconds at duty cycles up to 0.0002. The reliability of the rising sun design and the high current density Philips' type impregnated cathode ensure relatively long tube life. Modulator design is simplified by the low input capacitance of a rising sun tube in conjunction with the low pulse voltage requirements and relatively high efficiency (8%). This is particularly desirable in the very short nanosecond pulsewidth region needed to fully exploit radar resolution possibilities at this high frequency. Development of the 3.2-mm magnetron was based on experience obtained in the development of a family of existing millimeter magnetrons, in particular, the 4-mm and the 2.5-mm tubes. This paper describes the anode and the hobbing method used for making it. Also described is the cathode and procedures by which it is aligned in the anode: optically during assembly, and electrically after evacuating the tube. Electrical test procedures and the results are described for both cold and hot tests, including descriptions of specialized WR10 waveguide equipment designed for use in evaluating these tubes.