Generation of cherenkov superradiant pulses with correlated phases defined by sharp edges of high-current electron bunches
Recently coherent summation of several SR pulses generated in parallel channels has been demonstrated in X- and Ka wavelength bands. This possibility is caused by picosecond stability of explosive emission from a cold cathode and strong correlation of phase of the SR pulses with respect to the leading edge of the electron bunch. In fact stimulated SR emission is initiated by spontaneous mission from bunch leading edges. In report we describe results of recent experiments and develop a theoretical model which covers both spontaneous and stimulated Cherenkov emission.
Generation of Cherenkov superradiance pulses with a peak power exceeding the power of the driving short electron beam.
Theoretical investigation of a short electron beam (extended bunch) interaction with a backward wave propagating in a slow wave structure demonstrates the possibility of producing ultrashort superradiance pulses with a peak power which exceeds the power of the driving beam (conversion factor K>1). It is shown that a nonuniform slow wave structure with optimized profile is beneficial in order to increase the conversion factor. The results of theoretical analysis are confirmed by the experiments. At X band using the SINUS-150 accelerator (4 ns, 330 kV, 2.6 kA) 0.6-0.8 ns superradiance pulses with a peak power of 1.2 GW and a conversion factor of 1.5 were obtained. Similar experiments at Ka-band based on the RADAN-303 accelerator (1 ns, 290 kV, 2.5 kA) demonstrated production of the superradiance (SR) pulse with duration 200 ps and peak power about 1 GW (conversion factor of 1.4).
Global attractivity in time-delayed predator-prey systems
Abstract For a predator-prey model with time-delay due to gestation, criteria are obtained for persistence and global attractivity. The global attractivity criteria apply only to models with a decreasing prey isocline.