592 



BELL SYSTEM TECHNICAL JOURNAL 



pulse repetition rate, enabling one to determine the gap dissipation for any 

 project by multiplying the loss per pulse by the repetition rate. 



This area can be divided into two parts as suggested by the two shaded 

 blocks I and II. The first part corresponds to the energy dissipated initially 

 by the trigger and then by the pulse forming network in the brief transient 

 period when the voltage across and the current through the gaps are changing 

 rapidly. The former is comparatively small and usually can be neglected. 

 The latter attains a maximum value of power when the impedance of the 

 gaps approximates that of the load. The second so-called steady state part, 

 corresponding to block II, represents the energy lost during the main pulse 



Hi 0.020 



u 0.015 



0.005 





1.5 2.0 2.5 3.0 3.5 



PULSE DURATION IN MICROSECONDS 



Fig. 20 — Dissipation per gap per pulse vs. pulse duration for 1B22 gaps operated in 

 series with a peak current of 70 amperes. 



when the impedance of the gaps is low and comparatively constant. Its 

 value will depend on both the pulsing conditions and the gaps themselves. 

 A calorimetric study was made of the dissipation of gaps as affected by 

 various parameters. This method was superior to the oscillographic 

 approach in that it afforded greater accuracy and ease of measurement. The 

 curve, Fig. 20, shows observations in terms of joules per pulse per gap 

 obtained calorimetrically with the 1B22 type tube as a function of pulse dura- 

 tion in microseconds. The peak current in all cases was 70 amperes and the 

 trigger energy was included. It is clear that for pulse durations greater than 

 0.5 microseconds the dissipation D in joules per pulse per gap is given by 



D ^ A -^ Bt 



(1) 



