A high frequency vircator microwave generator

The virtual cathode oscillator (Vircator) has the potential for producing very high power microwave pulses in the centimeter and millimeter wavelength regimes. In a foilless diode configuration it is tunable by adjusting the imposed axial magnetic field. This permits high frequency operation. In a foil diode or reflex triode tuning is accomplished by changing the A-K gap spacing. The microwave generation will be coherent and efficient, if electron reflexing into the diode region is prevented. Gigawatt power levels have already been produced in the centimeter regime. For an injected current a factor of three greater than the limiting current, equation. Because the oscillating beam is equivalent to a deformable dipole, the preferred waveguide mode for an axisymmetric beam in a straight-walled cylindrical guide is TMDn where n = D/λo, D is the waveguide diameter and λo is the free space wavelength. Thus, D/λo should be chosen to be close to an integer value. Note that both the limiting current and the cutoff wavelength depend on the guide dimensions and geometry. Both must be considered in choosing an experimental configuration.