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Long pulse gas lasers utilizing double-discharge circuits are different from the single-short pulse gas lasers in that they do not require all of the desired energy to be deposited into the peaking capacitors prior to ignition of the main gap. Instead, the majority of the energy is held in another capacitor that is then discharged in the form of a longer duration discharge pulse output compared with that of single-short pulse lasers. Extended stability of the discharge is typically achieved by igniting the main gap discharge at higher ignition voltages. Several double-discharge circuit topologies exist in the literature. However, each topology has its own disadvantages primarily centered around the components needed and the resulting complexity. In this article we introduce the application of the new hybrid circuit pulsed power topology as a double-discharge circuit with high ignition voltages. The hybrid circuit pulsed power topology was originally published by the authors of this article in their previous publication titled “A New Hybrid Pulsed Power Circuit Topology for Gas Laser Applications.” The advantage of the hybrid circuit as a double-discharge circuit is that it does not require any special device [e.g., semiconductor opening switch (SOS) diode] and can use commonly available components. [ABSTRACT FROM AUTHOR]

A major decision surrounding the design of pulsed power circuits for gas lasers is the choice between a thyratron and solid-state switches. The thyratron is a mature device technology whose cost is increasing. The ratings of solid-state switches still do not match those of a thyratron. Pulse transformer and pulse compression circuits must be added to overcome the lower ratings of solid-state switches leading to a higher parts count and cost. This article proposes a new solid-state pulse power topology called the hybrid circuit topology to address the parts count and cost issue. The hybrid circuit makes use of a combination of capacitive and inductive energy storage to reduce the time required to transfer the energy from the transformer primary to the secondary side. This ultimately reduces the quantity of magnetic material used in the pulse compression circuit. [ABSTRACT FROM AUTHOR]

Possible sulfur hexafluoride (SF6) gas alternatives have been the focus of research and development in science and industry for many years. After the revision of the European F-Gas regulation 517/2014, the investigation has been even more intensified. One option for an approach for realizing an environmentally friendly switchgear for the high-voltage level is a combination of gas circuit breaker (GCB) and vacuum circuit breaker (VCB) in a series connection. Both switching concepts have advantages: the VCB can withstand very steep rising transient recovery voltages after current zero (CZ), while the GCBs are able to withstand high amplitudes of recovery voltage. In this investigation, the coupling and interaction of a series connection of a VCB and a GCB filled with carbon dioxide (CO2) is experimentally characterized in a basic study. The postarc current of the axial-magnetic-field-type VCB is identified as an important parameter influencing the interaction between both circuit breakers in the series connection and subsequently in the focus of the investigation. The different CZ behavior of a single VCB and a hybrid circuit breaker is compared. The voltage distribution across the two circuit breakers is the main assessment criterion for a series connection. In the first phase after CZ, the postarc current has a dominant influence on the voltage distribution; after that, a transition phase leads to capacitive voltage division phase. In order to control the voltage distribution, both capacitive and resistive voltage controls are investigated. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamic dielectric recovery synergy (DDRS) of hybrid circuit breakers (HCBs) with CO2 gas and vacuum gaps in series. The interaction between the vacuum arc and CO2 gas arc is simulated by the continuous transient arc model and Mayr arc model. The simulation results indicate that the extra methods, for example, dividing capacitors, are needed to obtain optimal DDRS of HCB. The prototype of HCB and the test circuit are established. The influence of the coordination of arcing time, dividing capacitors, and the CO2 gas pressures on the transient recovery voltage (TRV) distribution and the breaking capacity is investigated. The differences of HCBs with SF6 gas and CO2 gas are also compared. According to the results, favorable DDRS in HCB can be obtained in the condition that the vacuum gap endures the initial TRV while the following major TRV distribution is mainly depended on the dynamic dielectric in CO2 gas gap. However, the dynamic dielectric recovery of CO2 gas gap is limited by the structure of rotating arc CO2 gas interrupter in this paper. In the future, the interruption capacity of HCB based on CO2 gas can be improved by synergy control, as the development of CO2 gas circuit breakers. [ABSTRACT FROM PUBLISHER]

This paper focuses on the vacuum arc commutation between the vacuum arc and the parallel-connected insulated gate bipolar transistor (IGBTs) of dc microgrid hybrid circuit breakers (HCBs). The principle of the dc HCB is analyzed and the vacuum arc commutation is the important process in dc HCB interruption, in which the arcing time and the interrupting time are depended. The test circuit of the vacuum arc commutation is established by simplifying the parallel-connected IGBTs to an on-state resistance with large thermal capacity. The influence of the magnitude of the main current, the resistance of the IGBTs, and the externally applied transverse magnetic field (TMF) on the vacuum arc commutation is investigated by the electrical measure and the development of vacuum arc which is observed by a high-speed CMOS camera. The criteria of the vacuum arc commutation are obtained. The interaction between the vacuum arc commutation and the externally applied TMF is researched and the optimal magnitude of the TMF is gained. The vacuum arc commutation characteristics of dc HCB can be useful for parameters design and control strategy. [ABSTRACT FROM PUBLISHER]

This paper describes the detailed design of the quench protection circuits (QPCs) for the superconducting toroidal field (TF) and poloidal field (PF) magnets of the satellite tokamak JT-60SA, which will be installed in Naka, Japan. The nominal currents to be interrupted and the maximum reapplied voltages are 25.7 kA and 2.8 kV for the TF QPCs and 20 kA and 5 kV for the PF QPCs. The innovative solution proposed in the QPC design is based on a hybrid circuit breaker (CB) composed of a mechanical bypass switch for conducting the continuous current, in parallel to a static CB for current interruption. The main choices of the final design are presented and discussed, either to confirm or to update and complete the study performed at the conceptual design level. [ABSTRACT FROM PUBLISHER]