The design and characteristics of a megawatt space-harmonic traveling-wave tube

The tube described in this paper has a pulsed output power of one megawatt with 9.6 per cent bandwidth, where bandwidth is defined as the 3db points for saturation power. Saturation gain is about 20 db, which is 6 db below the low-level gain. This is a space-harmonic S-band structure, designed to operate at a beam voltage of 10⁵volts and perveance of 2 × 10^-6. Field configurations for the lowest and next higher pass bands are drawn, based upon a field analysis and cold measurements. The impedance determined by perturbation measurements is compared to the impedance for the forced sinusoid inside a closed region, and it is found that the tube has about four times the minimum storage energy necessary to obtain the same bandwidth.