604 BELL SYSTEM TECHNICAL JOURNAL 



One arrangement developed by W. Shockley to meet these requirements 

 used a thyratron as a switch to generate pulses. High vacuum tubes were 

 used at low voltages for comparatively long-time intervals in the driving 

 circuit. Deficiencies of the thyratrons available at that time prevented the 

 generation of pulse powers as high as required. With the earlier experience 

 on low-level coil pulsers in mind, it was natural to think of using a non-linear 

 coil for switching pulses at high level, in place of the thyratron. Much 

 development was required to arrive at suitable circuits embodying the basic 

 ideas, to build non-linear coils capable of withstanding high voltages, to 

 proportion the circuit elements for efficient operation at specified powers 

 and pulse durations, and to shape the output pulse to the desired flat-topped 

 form. 



This development resulted in a power pulser mounted in an oil-filled steel 

 box, with associated high vacuum tubes of the sturdiest sort mounted 

 externally, operated from a 1200 volt d-c. supply. It was suitable for installa- 

 tion integral with the antenna, and rugged enough to withstand gun blast and 

 shock. Life of the pulser box components is long, and performance stable 

 with time and temperature. The time of pulse emission is linked precisely 

 to the input wave, practically independent of voltage and frequency vari- 

 ations over a suitable range. Such precision timing, or freedom from jitter, 

 permits starting the indicator equipment in advance of the pulse emission 

 time so that target ranges may be accurately measured. The power 

 rectifier voltage is much lower than that of the pulse applied to the mag- 

 netron, and the pulser works Jirectty into the magnetron without requir- 

 ing an intermediary pulse transformer. 



Subsequent developments left unchanged the general form of the circuit 

 and its mounting, but were devoted to achieving various pulse widths, 

 powers, and pulsing rates to suit different applications. Pulse widths 

 covered a range from two-tenths to over one microsecond, peak powers 

 ranged from 100 to 1000 kw, and pulsing rates ranged from 400 to 3600 

 pulses per second. 



Non-Linear Con, Structures 



An idea of the general form and makeup of non-linear coils used in various 

 radar developments can be had from the photograph of Fig. 1. All cores 

 shown there are made of molybdenum permalloy tape, one mil thick. Insu- 

 lation is electroplated on the tape in a silicic acid bath, and the tape is wound 

 in ring form. After the standard magnetic anneal of 1000°C in hydrogen, 

 the coating of insulation a fraction of a mil thick adheres firmly to the tape. 



The smallest coil shown in Fig. 1 seen just in front of the oil filled 

 container in which it is mounted is used for low-power pulse generation. 

 Its core weighing 7 grams is wound on an isolantite form. 



