628 



BELL SYSTEM TECHNICAL JOURNAL 



has a value of l.SO.OOO micromhos, which agrees fairly well with the value 

 computed from the jfcomctrical capacitance. As anode current is drawn and 

 a space charge conchtion i)revails, b drops to a value of 125,000 micromhos. 

 Theoretical considerations would predict a drop of about 40% in the case 

 of a single-velocity electron stream. This is somewhat greater than the drop 

 exhibited in Fig. 6. 



0.5 1.0 1. 



ANODE VOLTAGE, Vq 



Fig. 8 — Effect of heater voltage upon g/g^. 



Figures 7 and 8 show the effect of cathode temperature on go and the ratio 

 g/gQ . The parameter used to represent the cathode temperature is the heater 

 voltage Vh ■ As the heater voltage is raised the total conductance g increases. 

 The ratio g/gn , however, decreases, particularly for low or negative anode 

 voltages. This means that, with a given anode voltage, as the cathode tem- 

 perature is raised, go increases more rapidly than g. If the curves of Fig. 8 

 are replotted in terms of Jo rather than F'o , the ratio g/go is relatively inde- 

 pendent of Vh ■ This is shown in Fig. 9. 



The results of measurements on another diode are shown in Fig. 10. 



