An explosively driven high-power microwave pulsed power system

The concept of a new two-stage fuse for high power pulse forming

This manuscript introduces the concept, physical operating principle and studies on a new and unique two stage forming fuse (TSFF) with interstage spark gap commutation and presents its application for forming high power pulses of extreme parameters. The paper classifies TSFF performance and compares it with conventional single-stage forming fuses. The conclusions are supported by analytical and experimental studies in laboratory conditions. The design of the TSFF prototype as well as the applied measurement methods and test stands are also presented. The developed technology of the TSFF enables the achievement of unprecedented parameters of high-power pulses with overvoltages reaching 800 kV and pulse power of tens of GW in a very compact design. The unique properties of the TSFF enable its efficient integration with a wide range of energy sources, even with very limited current rising steepness or limited output voltage, which has not been possible so far with conventional single-stage forming fuses. The proposed system can be easily scaled, while ensuring much greater flexibility of applications.

Compact high-power microwave divider and combiner

A novel, compact, TM01-TE10 mode power divider and a novel, compact, four-way TE10-TM01 mode power combiner were theoretically designed and experimentally tested as a proof of principle. The theoretical and experimental S parameters are consistent with each other. High-power experiments show that their power capacities are no less than 1.5 GW and 3 GW, respectively. The devices have the merits of high power capacities and low insertion losses.

A compact two-way high-power microwave combiner

A compact 2-way high-power microwave (HPM) waveguide combiner as an important equipment to realize the coherent microwave combination was theoretically designed, built, and proof-of-principle experimentally tested. The theoretical and experimental S-parameters are basically consistent with each other: return loss <-25 dB, and the isolation degree between 2-channels of the HPM combiner >25 dB to avoid the inter-modulating between the HPM sources. The C-band HPM experiment was carried out, and the power capacity of the HPM combiner was demonstrated to reach multi-gigawatts.

Exploding-wire experiments and theory for metal conductivity evaluation in the sub-eV regime

Copper and silver wires are subjected to pulsed high current densities producing high density metal plasma in the sub-eV regime with atmospheric air as a background gas. Numerical simulation via application of the one-dimensional magnetohydrodynamic partial differential equations solved simultaneously with the constraining circuit equations is presented. The simulations require accurate knowledge of the material equation of state (EOS) and transport properties; the LANL sesame database is applied for the EOS in all cases. Two electrical conductivity models are applied. First, the Lee-More-Desjarlais (LMD) and its modification, the quantum LMD (QLMD) conductivity, which have been well proven at higher temperatures, are applied. Simulations with the LMD and QLMD data indicate that the conductivity data as well as the MHD methodology are accurate in the sub-eV regime of interest. A less computationally involved, empirical conductivity model is applied in the same regime to explore its temperature-density range of applicability compared to the more sophisticated model.

Note: compact helical pulse forming line for the generation of longer duration rectangular pulse

The helical pulsed forming line (PFL) can generate longer duration rectangular pulse in a smaller length. A compact PFL using helical water line is designed and experimentally investigated. The impedance of the helical PFL is 22 [ohm sign]. The compactness is achieved in terms of reduction in length of the PFL by a factor of 5.5 using helical water PFL as compared to coaxial water PFL of same length. The helical PFL was pulsed charged to 200 kV using a high voltage pulse transformer in 4.5 μs and discharged into the matched 22 Ω resistive load through a self-breakdown pressurized spark gap switch. The rectangular voltage pulse of 100 kV, 260 ns (FWHM) is measured across the load. The effect of reduction in water temperature on the pulse width is also studied experimentally. The increase in pulse width up to 7% more is observed by reducing the temperature of the deionized water to 5 °C. It will further reduce the length of the PFL and make the system small for compact pulsed power drivers.