| Explosive magnetic generator of frequency (EMGF) is a kind of wideband radiation device in which explosive magnetic compression generator (EMCG) is used to drive a capacitive load directly. By means of exploding the explosive to drive the armature to compress the magnetic field, the energy of the explosive is transformed to electromagnetic energy, and LCR oscillation is formed in the circuit, and then radiated into the space by antenna or solenoid in itself. As a kind of directly drived device, EMGF is small, light and low cost, at the same time, wideband and ultra wideband frequency radiations could be generated by EMGFs according to some references. Some basic theoretical and experimental researches are carried out on direct feeding and indirect feeding EMGFs,In theory,the equivalent circuit model of EMGF is applied to explain the physical process of EMGF generating the current oscillations. All kinds of loss during the operation of EMGF are analysed and calculated and the measures to decreace these loss when desiging the devece are given. The parameters of the device such as inductance and the resistance of the EMGF are calculated. In calculation,the non-ohmic loss is equivalent to ohmic loss and shown as an equivalent resistance in the circuit.The circuit during the running period is simulated by PSpice, and the feeding current, load current and the load voltage are obtained by simulations, and the results agree with the experimental results basically.In experiment,two kinds of EMGF are made according to the experiences and the theoretical calculations. The experimental environment and the measuring system are improved,especially the measuring system of wideband radiation is built and improved, Every system is used in the experiments successfully,the experimental environment is proved safe,the time-controling system is precise, the initial source is stable and the measuring system is reliable. Several EMGFs are designed and tested in this paper, including direct and indirect feeding ones. For the indirect feeding apparatus, 23 nF and 10 pF capacitive loads are used respectively, and a 10 pF load is applied in the direct feeding apparatus. All these EMGFs have ~130mm diameter and ~200mm length. The experimental waveforms similar to the waveforms reported in other papers are detected in both of the two kinds of EMGF experiments. The operation time of the two kinds of devices is ~ 25μs, and the oscillation time of the load current and the spatial radiation is ~15μs. In the typical indirect feeding EMGF experiment, the voltage of the charging capacitor is charged to 2 kV, and the maximum load current is 2.2 A, and the maximum electric field of the radiation detected 10 m away from the device is 598 V/m, and the frequency of the spatial radiation is within 12.5 MHz. In the direct feeding EMGF experiment, the voltage of the charging capacitor is charged to 3 kV, and the maximum load current is 0.8 A, and the maximum electric field of the radiation detected 10 m away from the device is 209 V/m, and the frequency of the spatial radiation is within 12.5 MHz. The maximium load current and the radiation electric field of the direct feeding EMGF is less than these of the indirect feeding EMGF.The outputs of the two kinds of EMGF are stable, and the fact that EMGFs can generate"fish"shape wideband electromagnetic waveforms is proved, wideband radiation frequency range and electric field are similar with the typical experimental results home and abroad. A new mechanism of generating wideband radiation by using a capacitor with high-capacity in EMGF is found. More theoretical and experimental researches are needed in the future. |
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