MAGNETRON AS GENERATOR OF CENTIMETER WAVES 



183 



from one segment to the next depends upon the mode of oscillation of the 

 system as a whole. The restriction on the phase difference stated above 

 requires the sequence of anode segment potentials at any instant to contain 





A 



t + 1 /4 T 

 t+ 2/4 T 

 t + 3 /4 T 

 t, + 4 /4 T 

 t + 5 /4 T 

 t + 6 /4 T 

 t * 7 /4 T 

 t -^ 8/4 T 

 t + 9 /4 T 

 t + 1 /4 T 

 t + n /4 T 

 t+ 12/4 T 

 t+ 13/4 T 

 t, + 1 4 /4 T 

 t + 15/4 T 

 t <• 16/4 T 







|k| =28 20 



Fig. 9. — A plot showing the tt mode anode potential wave at several instants in an eight 

 resonator magnetron and the mean paths of electrons which interact favorably with the 

 RF field. The plot is developed from the cylindrical case, the shaded rectangles at the top 

 representing the anode segments. The anode potential variation is a standing wave, 

 shown here for a sequence of instants one quarter period (r/4) apart. Note that the po- 

 tential is constant across the anode surfaces and varies linearly between them. Electrons 

 interacting favorably with the RF field cross the anode gaps when the field there is maxi- 

 mum retarding as indicated by the filled circles. The lines for | ^ | = 4, 12, 20, 28, • • • rep- 



, r , 1- • 1 1 1 -i- 27r/ 1-kJ lirf 



resent mean paths of electrons traveung with mean angular velocities —r-, -rj, -^j 



l-n-f 



-;r— , • • • around in the interaction space. 



Since the field is a standing wave, it is clear that 



electrons possessing these velocities in either direction may interact favorably with the RF 

 field. 



n complete cycles in one traversal of the cylindrical anode, n still denoting 



N 

 the integers 0, 1, 2, • • • , - . In general, these anode potential waves may 



be standing waves or waves travehng around the anode structure in either 



direction with angular velocity — ^ radians per second, where / is the RF 



