204 



BELL SYSTEM TECHNICAL JOURNAL 



value, perturbation of the electron motion occurs, decreasing the efficiency 

 of interaction with the traveling wave and manifesting itself on the perform- 



CONSTANT MAGNETIC FIELD-GAUSS 



CONSTANT POWER OUTPUT- KILOWATTS 



CONSTANT OVERALL EFFICIENCY 



8 10 12 14 16 U 



DC CURRENT, I, IN AMPERES 



20 22 24 26 



Fig. 20. — A performance chart for a magnetron which has present in its interaction field 

 a contaminating component independent of azimuth. Note the efficiency "valley" ap- 

 pearing along the line B = 3920 gauss (compare with Fig. 17). The wavelength of the 

 magnetron being 3.18 cm., \B along the efficiency "valley" is 12,500 gauss-cm. The data 

 were obtained on a magnetron having a "rising sun" type resonator sj'stem and are repro- 

 duced here through the courtesy of the Columbia Radiation Laboratory. 



ance chart as a "valley" in operating efficiency appearing along the constant 

 B line for which \B = 12,500 gauss-cm. In Fig. 20 is plotted the perform- 

 ance chart of a magnetron, having a "rising sun" type anode structure which 



