Design, analysis, and performance of an unregulated CFA modulator requiring 0.1% voltage amplitude stability

The authors describe how a high-voltage hard tube modulator design proceeds from specification, to design, to computer analysis and hardware performance. Emphasis is placed on factors in attaining a 0.1% pulse to pulse voltage amplitude stability. This design approach is significant in the determination of how close predicted performance matches measured performance. Other unique design aspects are the use of digitized V-I tube data in the prediction analysis and the use of switch tube DC filaments. Key operating requirements of the desired design are the ability to operate grid saturated or unsaturated while providing variable voltage and current pulses up to -20 kV and 40 A peak. Output voltage is regulated to 0.1% for PRFs (pulse repetition frequencies) from single shot to 7 kHz and pulse widths from 0.4 μs to 70 μs. Rate of rise of voltage is adjustable from 80 kV/μs to 130 kV/μs