Experimental investigation on a long pulse, relativistic extended-interaction-cavity oscillator locked with coupler

The physics of modulation and RF extraction of an S-band, long pulse, relativistic extended-interaction-cavity oscillator (REICO) is studied in this paper via experiment, theory and simulation. The origin of pulse shortening and mode competition of the REICO driven by the long-pulsed intense relativistic electron beams (IREBs) is explored. The modified cavity structure with coupler is proposed for the first time to suppress the pulse shortening and mode competition. The pulse width of the modulated IREBs is increased from 60 ns to 140 ns, and the magnitude of the modulated IREBs is increased from 2 kA to 5 kA. The radiation microwave power and efficiency are promoted obviously after adjusting the parameters of the IREBs and the leading magnetic field. Using a 500 kV, 4.2 kA, 210 ns, 20 Hz