Nonlinear reactive circuits driven by magnetic flux compression generators

Abstract

Presently, generators of broadband microwave radiation, using spiral magnetocumulative generator (MCG) as the energy source, are under intensive investigation [A.V. Pashenko, et al., 1998; A.B. Prishchepenko, 1991]. In the majority of the existing designs, researchers are attempting to generate high-power radiation over the broad spectral range by directly connecting the MCG to an antenna or by using the helical coil of the MCG as the radiating element [A.B. Prishchepenko, 1991; A.B. Prishchepenko, et al., 1996]. These are called direct drive devices. It is understood that the efficiency of these devices is very low, which is attributed to the impossibility of matching the energy source, with output characteristics that change in time, with antenna sizes no greater than tens of centimeters and to the fact that the characteristic length of the MCG current pulse, driving the antenna, ranges from 10/sup -7/ to 10/sup -6/ s. In addition, the maximum amount of energy lies within the spectral range 10/sup 6/ - 10/sup 7/ Hz, which corresponds to wavelengths of 300 - 30 m. Since the effective length of the antenna for these devices comprises only a fraction of the wavelength of the driving oscillations, the radiation efficiency is very small. As a result, direct drive devices radiate relatively low powers and have virtually isotropic radiation patterns, which is unacceptable for a number of applications. These problems can be solved by several different methods. One of them is to design a modulator, operating over a broad frequency range, corresponding to a wavelength less than or close to the size of the transmitting antenna, for coupling energy from the MCG into the antenna. This kind of modulator would not only provide effective modulation of strong currents, generated by MCG, but also enrich the spectrum of the current fluctuations, by shifting the spectrum to higher frequencies [A.V. Pashenko, et al., 1998]. This paper considers one possible type of modulator and presents the results of computer simulations.