On the possibility to create the plasma amplifier with direct radiation of electromagnetic waves

The possible scheme of plasma amplifier with direct radiation is proposed. Energy of amplified oscillations is coupled out due to transitional radiation on the plasma border retained by constant magnetic field. For this purpose the beam that is injected into plasma column should be slightly defocused. Paraxial electrons of the beam provide plasma-beam interaction and signal amplification. Defocused peripheral electrons modulated by HF field created in the beam-plasma system move along spiral trajectories. Thus, they periodically come into the plasma column and come out of it. Each time transitional radiation takes place. It can result to sufficiently high effectiveness of the beam modes' transformation into electromagnetic waves