848 



THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1956 



5.5 

 5.0 

 4.5 

 4.0 

 3.5 

 3.0 

 2.5 

 2.0 

 1.5 

 1.0 

 0.5 

 



0.2 



0.4 



0.6 



0.8 



1.0 



1.2 



1.4 



1.6 



i.a 



Fig. 4 — Efficiency/C for large values of C and with elevated beam voltage. 

 Efficiency seriously departs from proportionality to C at C = 0.14, where a maxi- 

 mum efficiency of about 38 per cent is measured. 



MAGNETIC 

 SHIELD 



COIL 



ELECTROSTATIC 

 ELECTRON LENS (3) 



FLOURESCENT 

 SCREEN, 



NOTCHED 

 GLASS 

 RODS (3) 



DEFLECTING 

 PLATES 



DEFLECTING 

 COILS 



DEFLECTING 

 PLATES 



Fig. 5 — The velocity analyzer. A sample of the spent electron beam is ac- 

 celerated to a high potential, swept transversely with a synchronous voltage, 

 sorted with crossed electric and magnetic fields, and focused onto a fluorescent 



screen. 



pattern, Fig. 7(a), is representative of the low level (linear) conditions 

 (22 db below the drive for saturation output) . The dashed curve repre- 

 sents the voltage on the circuit, inverted so that electrons can be vis- 

 ualized as rolling down hill on the curve. The phase of this voltage rela- 

 tive to the electron ac velocity is computed from small signal theory, but 



