Construction of SOS-based devices

The ideology of our approach is shown schematically in Fig. 4. The thyristor charger (TCU) receives a metered amount of power from supply mains. The TCU supplies 1-2 kV in 10-100 чs to the magnetic compressor (MC). The MC compresses the power in time to about 300-600 ns and steps up the voltage to hundreds of kV. The SOS acts as the final power amplifier: it converts the power to the time interval of 10-100 ns and steps up the voltage by a factor of 2 to 3.

Fig. 4

The magnetic compression unit has been introduced in the circuit to match the pulse parameters at the TCU output with the pumping pulse parameters of the SOS. The MC should generate pulses having the length of a few hundred of ns and the voltage of hundreds of kV so as to produce nanosecond pulses with the amplitude of about 1 MV at the output of the device. Thus, given the input pulse with the amplitude of 1-2 kV and the length of 10-100 чs, the MC should compress the power in time nearly by a factor of 100 and step up the voltage by 100 to 400 times.

Fig. 5

Figure 5 shows a schematic circuit diagram of a magnetic compressor, which provides time compression of power and simultaneous increase in the output voltage [15]. As power is compressed in the compressor, voltage is increased 2-fold in each cell. Neglecting the active loss of power, the output voltage of the MC is 2n higher than the input voltage (n being the number of capacitor cells). In addition, the proposed MC does not require additional circuits for magnetization reversal of the magnetic switch core, since magnetization reversal is realized automatically thanks to opposite directions of charging and discharging currents in every switch (charging and discharging currents are shown in the figure with dashed and solid lines respectively). One more distinctive feature of this circuit is that power is double-compressed in each capacitor cell thanks to re-charging of the lower capacitors. Therefore two capacitor cells are enough to compress power in time by two orders of magnitude.

Fig. 6

Another significant problem incurred in the transfer of power from the MC to the SOS is the circuit design for two-circuit pumping of the SOS in the mode of reverse current amplification. The matching circuit is shown in Fig. 6 [3]. The reverse pumping capacitor Cp and the reverse pumping magnetic switch MS- (or a pulse transformer) are installed between the MC output and the SOS. As soon as the forward pumping switch MS+, which acts as the output switch of the MC, is saturated, power is supplied from the last cell of the compressor to the capacitor Cp. The charge current I+ of the capacitor Cp serves simultaneously as the forward pumping current of the SOS (see Fig. 7).

Fig. 7

The increasing voltage across Cp reverses magnetization of the switch MS-. As soon as the switch operates, the SOS receives the reverse current I-, which is several times as high as I+. Power from Cp is transferred to the inductor of the reverse pumping circuit (winding inductor of the saturated switch MS- or an additional inductor). After the SOS cuts off the current, power is fed to the load as a short nanosecond pulse.