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Repetitive high-voltage square pulses are of great importance for producing long-pulse electron beams and high-power microwaves. One of possible technologies for the generation of such pulses is a Marx generator using pulse forming network (PFN) stages, often combined with a pulse sharpening technique to reduce the rise time to a few nanoseconds (peaking stage). This paper presents an innovative design, named the “zigzag design,” for the optimization of the compactness and of the rise time of 400-kV–85-ns PFN-Marx. Thanks to this design, the 16 stages of this generator, which delivers an open circuit output voltage of 720 kV, fit in a 650-mm length. For a slightly overmatched load ($Z_{\mathrm {load}} = 100 ~\Omega$), the output voltage reaches 400 kV with a rise time as less as 5 ns. The inductance reduction associated with the innovative zigzag design, which allows this sharp rise time with no need for a peaking stage, is described. The 85-ns plateau duration of the pulse is given by the PFN construction of each stage, which is based on six ceramic capacitors (2.1 nF–45 kV) connected within a strip line. The 16 PFN stages are housed in a 360-mm diameter gas pressurized vessel. Burst mode operation for a duration of 10 s at a pulse repetition frequency of 100 Hz is reported, for a resistive load and for the electron beam diode of a X-band relativistic backward-wave oscillator (BWO). To reach further compactness, the BWO system is integrated on side of the generator vessel and a U-shaped gas pressurized line connects both systems through a compact conical vacuum insulator. [ABSTRACT FROM AUTHOR]

This paper is concerned with the development and testing of a compact flat format multichannel electrically triggered rail spark gap. It is tested for multichannel discharge under atmosphere for high reliability. Multichannel discharge rail spark gaps can be developed using laser trigger or fast rising trigger voltage pulse (>5~kV/ns). The extra volume and weight added by laser or fast triggering circuits limit the use in pulse power applications. An electrically multitriggered low-inductance spark gap is developed. It is used as a multichannel low-inductance discharging element in a fast rising high-current generation system. The trigger of such rail gap is realized using the set of round copper pins similar to single trigger pin in a field distortion spark gap. In parenthesis, five different trigger pins are located in main trigger plate and these are isolated with high impedance. Therefore, five different trigger signals are generated with time difference of tens of nanoseconds. The major material erosion at five points of both stainless steel main electrodes confirms the multichanneling discharge. The main gap spacing in this switch is 4 mm and the trigger is located close to the ground electrode for reducing the delay time and jitter in delay time. This paper shows the trigger circuit design, main gap voltage, and trigger voltage effect on the closing of the spark gap and picture of electrodes after use. [ABSTRACT FROM AUTHOR]

This paper discusses the modeling of a peaking switch to study the reduction in rise time for the subnanosecond duration pulses. The effect of the various shapes of input pulse, inductance, and interelectrode distance on the output voltage and wave shape is discussed in this paper. The modeling has been carried out using the electromagnetic and microwave modeling software of Computer Simulation Technology. [ABSTRACT FROM PUBLISHER]

Megavolt-class-triggered switches play a key role in large-induction voltage adder accelerators. This paper introduces a 2.8-MV, low-inductance, low-jitter, electrical-triggered, gas SF6 switch. The main section is a $V/n$ switch and the pretrigger section is a trigatron switch. Based on electric field simulation, experiment, and analysis, the structure and spacing of gaps, location of trigger disk, diaphragm, and switch inductance are all discussed. The primary test indicates that the switch can be operated in the range of 0.85–2.76 MV with the pressure of the SF6 changing from 0.1 to 0.9 MPa. The self-breakdown voltage is linearly related to the logarithm of the pressure, as the gap spacing and the voltage rise time are fixed. Three working modes were observed: self-breakdown, self-triggered, and ex-triggered. In the triggered modes, the switch jitter is <3 ns and the switch inductance is usually below 150 nH. [ABSTRACT FROM AUTHOR]

This paper provides analysis of experiments aimed at defining the capabilities of plasma opening switch (POS) for energy transfer to a load of inductance comparable with the inductance of the energy store vacuum section. The analysis is performed using the substantiated technique that allows quantitative estimation of the POS efficiency. Under the same conditions with a conduction current of ∼1 MA and POS voltage of ∼1 MV, the energy transferred to the load depends strongly on the transmission line design. When the electrode gap in the line is ∼1 cm, the energy delivered to the load is ∼40 kJ. Increasing the gap to ∼4-cm increases this energy to ∼100 kJ. [ABSTRACT FROM PUBLISHER]

SPHINX is a microsecond linear transformer driver located at Atomic Energy Comission (CEA) Gramat (France), which can deliver a current pulse of 6 MA within 800 ns in a Z -pinch load. Using the concept of the dynamic load current multiplier (DLCM), which was proposed by Chuvatin, we expect to increase the load current above 6 MA, while decreasing its rise time to \sim300 ns. The DLCM developed by the CEA Gramat and International Technologies for High Pulsed Power (ITHPP) is a compact system made up of concentric electrodes (autotransformer), a dynamic flux extruder (cylindrical wire array), a vacuum convolute (eight post-hole rods), and a closing switch (compact vacuum surface switch). The latter is a key component of the system, which is used to prevent the current from flowing into the load until the inductance builds up due to the implosion of the wire array. This paper presents the design and testing of the DLCM surface switch, resulting from both electrostatic simulations and experiments on the SPHINX generator. These studies, carried out either with or without load (open circuit), were valuable for a first experimental evaluation of the DLCM scheme in a microsecond regime and provided detailed information on the surface switch behavior. [ABSTRACT FROM AUTHOR]

In this paper, a novel six-channels annular plasma-jet chamber is designed and embedded in the trigger electrode of the three-electrode gas switch to generate multichannel plasma jets without air flow, which is used to trigger the gas switch to form multichannel discharge. Results of this paper show that the plasma-jet triggering can be conductive to steady formation of multichannel discharge. [ABSTRACT FROM PUBLISHER]