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Pulse forming lines (PFL) are widely applied in high-power pulsed power generators due to their high energy density and great ability with square waveform modulation. However, the three-cylinder coaxial Blumlein line (tPFL), a commonly used PFL structure, has low energy efficiency due to the difference in impedance of the outer and inner lines. In order to increase the outer line impedance and improve the output waveform of the PFL, a racetrack Blumlein pulse forming line (r-B PFL), formed by two inner cylinders, two middle cylinders, and one outer cylinder that resembles a runway shape, is proposed in this paper. The glycerin energy storage technology and the spiral line technology were applied in the PFL. Moreover, the r-B PFL was tested experimentally after its construction, yielding a satisfactory result. The PFL structure in which multiple middle cylinders share the same outer cylinder achieves a higher outer line impedance, leading to a high energy efficiency of the PFL, which contributes to the PFL development trend toward compactness and miniaturization., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

Pulsed power generators utilizing magnetic switch technology within the 100 ns scale have become widespread for surface treatment, high power microwave generation, and food processing, in which the dynamic characteristics of the magnetic switch perform an important function. The saturation process, electric field between layers, and energy loss are closely associated with the applied time scale of the magnetic core, which affects the dynamic characteristics of the switch. However, compared with the study within the microsecond scale, the dynamic characteristics of magnetic switches within the 100 ns scale have not been studied in depth. In this paper, the dynamic characteristics of a coaxial magnetic switch modulating pulse forming networks (PFNs) are studied via both field-loop co-simulation and scaled experimental test. It is found that increasing PFN section number (Ns) leads to an acceleration in the saturation process of the core, which helps understand the switch performance of the magnetic core more clearly. With respect to a specific magnetic switch based on a ferromagnetic core, it is quantitatively analyzed that increasing Ns from 1 to 10 leads to a 16.1% reduction in core saturation time (tsat), a 13.4% increase in eddy loss (EET), and a 5.7% rise in maximum interlamination field strength (Emax) under the 100 ns scale; however, tsat is reduced by 19.3%, EET increases by 5.2%, and Emax rises by 2.3% under the microsecond scale. The results could provide a design reference for magnetic switches in pulsed power generators., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

We report the first experimental demonstration of coherent combining of phase-steerable high power microwaves (HPMs) generated by X-band relativistic triaxial klystron amplifier modules under the guidance of pulsed magnetic fields. Electronically agile manipulation of the HPM phase is achieved with a mean discrepancy of 4° at the gain level of 110 dB, and the coherent combining efficiency has reached as high as 98.4%, leading to combined radiations with equivalent peak power of 4.3 GW and average pulse duration of 112 ns. The underlying phase-steering mechanism during the nonlinear beam-wave interaction process is furthermore explored by particle-in-cell simulation and theoretical analysis. This Letter paves the way for high power phase array in large scale and may stimulate new interest in research of phase-steerable high power masers.

One of the important research directions in pulse power technology is to increase power density and operational stability of compact high-power pulse transformers. In this paper, the research object is a high-power pulse transformer using combined insulation, and the operating characteristics are obtained using simulation and experiment methods. The experimental results show that the maximum output voltage of the transformer increases by 30% in the combined insulation. At the same time, the combined insulation transformers are safer and have better insulation holding capacity. Moreover, multiple breakdowns have less effect on the subsequent breakdown voltage of the combined insulation transformer. The average subsequent breakdown voltage after 30 breakdowns of combination insulated transformers is still higher than the first breakdown voltage of non-combined insulation transformers. In addition, the energy storage density of combined insulation transformers is ∼40% higher than that of non-combined insulation transformers because of the higher permittivity of Midel 7131 than transformer oil.

An all-solid-state microsecond pulsed power system has been tested in this paper. It can produce larger than 50 kV and microsecond-range pulses continuously for more than 9 × 10 4 shots into a resistive load at a repetition rate of 10 pps. The whole device has accumulatively operated more than 15 000 pulses at 100 Hz and 3 × 10 5 pulses at 10 Hz. This all-solid-state pulsed power system consists of a repetitive power supply, a four-stage Marx generator, a pulse forming network, and a resistive load. The repetitive power supply of the pulsed power system is calculated and analyzed first, followed by the introduction of the Marx generator and the three-section anti-resonance network. A polymer box of sodium chloride solution is applied as a resistive load with an impedance of 200 Ω. Repetitive experiments showed that this system is able to operate stably at 100 Hz repetition rate without failure.

The saturable pulse transformer (SPT) and six stage LC-Marx generator are proposed in this solid-state system. In the experiments, the output voltage of 14.5 kV and the rise time of 720 ns are achieved when the isolation inductance is 35 µH and the primary capacitor is charged to 350 V. The output voltage is 4.1 times larger than the charging voltage on the single capacitor. For larger output voltage and shorter rise time, isolation inductance is changed with the high-voltage silicon stack, which is a kind of rectifier diode consisting of several diodes enclosed in the resin with larger inverse voltage. In the same experiment condition, the output voltage is increased to 17.5 kV, which is 5.0 times larger than the voltage on the charging capacitor. The rise time gets down to 500 ns. The results show that the high-voltage silicon stack can further enhance the working performance of the SPT LC-Marx generator on the output voltage and rise time. Finally, experiments are carried out to test the working performance of the SPT LC-Marx generator at a repetitive frequency. The results show that the output voltage reaches 12 kV, which proves that the generator can work stably at 1 Hz.

A modularized generator with three long pulse modules is designed and constructed in this work. The long pulse module consists of a three-section anti-resonance network and a three-stage transmission line transformer. A single module can output a pulse with an amplitude of 33 kV and a full width at half maximum (FWHM) of 400 ns, when the primary energy storage system provides a voltage of 24 kV. After the three modules are connected in series in experiment, the modularized long pulse generator delivers a high-voltage pulse to the matched load resistor with a maximum voltage of 96 kV and an FWHM of 400 ns. Repetitive experiments at a repetition frequency of 10 Hz are also carried out.

A sub-microsecond-range pulse generator based on an antiresonance network and transmission line transformer (TLT) is presented in this paper. The three-section antiresonance network (TSAN) and three-stage TLT take the roles of the pulse forming module and pulse voltage boosting module of this generator, respectively. The TSAN is applied to obtain a high quality and fixed flat top quasisquare pulse with fewer sections, and the three-stage TLT is used to obtain a higher voltage gain. Experimental results show that if the charging voltage of the TSAN is about 15.0 kV, the amplitude and pulse duration of the output voltage of the TSAN are about 7.2 kV and 400 ns, respectively, which correspond to the theoretical calculation results. Meanwhile, the amplitude of the output voltage of TLT is about 22.0 kV, so the voltage step-up ratio of the three-stage TLT is about 3.05. This generator displayed in the publication can transmit voltage pulses with low loss.

A solid-state quasi-square pulse Marx generator has been designed, constructed, and tested in this paper. The spark gap switches of a typical Marx generator have been replaced by a fractional-turn ratio saturable pulse transformer (FRSPT), and a three-section anti-resonance network has taken the role of pulse forming module in this quasi-square Marx generator. For the switches, thyristors are used as the primary switches and the FRSPT is used as the pulse modulating switch. The experimental results show that if the charge voltage is about 1000 V, the output quasi-square pulse has an amplitude of 18.5 kV and a pulse width of 3.15 μs, and the experimental results verify the feasibility of the concept of an all-solid-state quasi-square square pulse Marx generator based on an FRSPT and anti-resonance network.

The high-power switch plays an important part in a pulse power system. With the trend of pulse power technology toward modularization, miniaturization, and accuracy control, higher requirements on electrical trigger and jitter of the switch have been put forward. A high-power low-jitter corona-stabilized triggered switch (CSTS) is designed in this paper. This kind of CSTS is based on corona stabilized mechanism, and it can be used as a main switch of an intense electron-beam accelerator (IEBA). Its main feature was the use of an annular trigger electrode instead of a traditional needle-like trigger electrode, taking main and side trigger rings to fix the discharging channels and using SF 6 /N 2 gas mixture as its operation gas. In this paper, the strength of the local field enhancement was changed by a trigger electrode protrusion length Dp. The differences of self-breakdown voltage and its stability, delay time jitter, trigger requirements, and operation range of the switch were compared. Then the effect of different SF 6 /N 2 mixture ratio on switch performance was explored. The experimental results show that when the SF 6 is 15% with the pressure of 0.2 MPa, the hold-off voltage of the switch is 551 kV, the operating range is 46.4%-93.5% of the self-breakdown voltage, the jitter is 0.57 ns, and the minimum trigger voltage requirement is 55.8% of the peak. At present, the CSTS has been successfully applied to an IEBA for long time operation.

High voltage pulse generators are widely applied in a number of fields. Defense and industrial applications stimulated intense interests in the area of pulsed power technology towards the system with high power, high repetition rate, solid state characteristics, and compact structure. An all-solid-state microsecond-range quasi-square pulse generator based on a fractional-turn ratio saturable pulse transformer and anti-resonance network is proposed in this paper. This generator consists of a charging system, a step-up system, and a modulating system. In this generator, the fractional-turn ratio saturable pulse transformer is the key component since it acts as a step-up transformer and a main switch during the working process. Demonstrative experiments show that if the primary storage capacitors are charged to 400 V, a quasi-square pulse with amplitude of about 29 kV can be achieved on a 3500 Ω resistive load, as well as the pulse duration (full width at half maximum) of about 1.3 μs. Preliminary repetition rate experiments are also carried out, which indicate that this pulse generator could work stably with the repetition rates of 30 Hz and 50 Hz. It can be concluded that this kind of all-solid-state microsecond-range quasi-square pulse generator can not only lower both the operating voltage of the primary windings and the saturable inductance of the secondary windings, thus ideally realizing the magnetic switch function of the fractional-turn ratio saturable pulse transformer, but also achieve a quasi-square pulse with high quality and fixed flat top after the modulation of a two-section anti-resonance network. This generator can be applied in areas of large power microwave sources, sterilization, disinfection, and wastewater treatment.

A compact high-voltage nanosecond pulse generator, based on a pulse transformer with a closed magnetic core, is presented in this paper. The pulse generator consists of a miniaturized pulse transformer, a curled parallel strip pulse forming line (PFL), a spark gap, and a matched load. The innovative design is characterized by the compact structure of the transformer and the curled strip PFL. A new structure of transformer windings was designed to keep good insulation and decrease distributed capacitance between turns of windings. A three-copper-strip structure was adopted to avoid asymmetric coupling of the curled strip PFL. When the 31 microF primary capacitor is charged to 2 kV, the pulse transformer can charge the PFL to 165 kV, and the 3.5 ohm matched load can deliver a high-voltage pulse with a duration of 9 ns, amplitude of 84 kV, and rise time of 5.1 ns. When the load is changed to 50 ohms, the output peak voltage of the generator can be 165 kV, the full width at half maximum is 68 ns, and the rise time is 6.5 ns.

A compact high power pulsed modulator based on spiral water Blumlein line, which consists of primary storage capacitors, a Tesla transformer, a spiral Blumlein line of water dielectric, and a field-emission diode, is described. The experimental results showed that the diode voltage is more than 500 kV, the electron beam current of diode is about 32 kA, and the pulse duration is about 180 ns. The distributions for electrical field in the spiral water Blumlein line were obtained by the simulations. In addition, the process of the charging a spiral Blumlein line was simulated through the PSPICE software to get the wave form of charging voltage of pulse forming line, the diode voltage, and diode current of modulator. The theoretical and simulated results are in agreement. This accelerator is very compact and works stably and reliably.