Numerical simulations of radial transit-time oscillator
Employing a 2.5-D PIC code, radial transit-time oscillator, is simulated numerically and the details are presented. The relations between output power and extractor size, radial cavity span and different modes are obtained. The results indicate that with the extractor size decreasing from 1cm to 2mm, the output power increases, and the relation between radial cavity span and output power coincides with that derived from linear theory. Comparison of different modes shows that TEM 1 is the most suitable mode to generate high power microwave. With a 200kV and 8kA electron beam, A 500MW, 5GHz peak output power microwave with mode TEM 1 is generated by simulation. The starting time to oscillate is less than 15ns. The peak efficiency is over 30%.