An. Vlasov et al., EFFICIENCY IMPROVEMENT IN RELATIVISTIC CERENKOV DEVICES DUE TO DYNAMIC CYCLOTRON-RESONANCE, IEEE transactions on plasma science, 24(3), 1996, pp. 870-878
The efficiency enhancement in relativistic electron devices with linea
r electron beams guided by homogeneous magnetic fields due to combined
Cerenkov-cyclotron interaction has been studied, The case considered
is when electrons do not satisfy the cyclotron resonance condition ini
tially, but start interaction with an electromagnetic field under the
condition of pure Cerenkov synchronism. Then, the changes in electron
energy due to the Cerenkov interaction lead some electrons to satisfy
the cyclotron resonance condition, This effect, called the dynamic cyc
lotron resonance, may play a significant role in strongly nonlinear re
gimes of a primary interaction when an electron beam is separated into
groups of accelerated and decelerated particles. For the case of the
primary Cerenkov interaction, two groups of accelerated and decelerate
d electrons can exist which interact with the RF field under the same
Cerenkov resonance condition, but due to dynamic shifts in electron cy
clotron frequencies, can resonantly interact with different harmonics
of the gyrofrequency. It is shown by numerical simulations that the ef
ficiency can be improved 25-28% for typical Cerenkov interaction up to
50% by choosing an appropriate value of the focusing magnetic held.