Current as high as 3.7kA has been generated using a single photoconductive semiconductor switch (PCSS) excited by a laser pulse with the energy of ∼8mJ and under a bias of 28kV. The PCSS with electrode gap of 14mm was fabricated from semi-insulating GaAs. Under different bias voltages the “on” resistances of the PCSS were measured. The longevity of the PCSS reached 350 shots at 20kV and 400A. The breakdown mechanism of the PCSS is analyzed based on the breakdown characteristics. It is shown that the breakdown of GaAs PCSS can be described by the electron-trapping breakdown theory.
We present a fusion-oriented pulsed power module M-50, which is based on the linear transformer driver (LTD) and magnetically insulated inductive voltage adder (MIVA) technologies. The module M-50, which consists of 50 identical LTD cavities connected in series, is one of the 60 modules of a fusion-scale pulsed power facility. M-50 is a comprehensive test bed for LTD integration and engineering validation. Each cavity consists of 32 bricks and has an output capability of 90 kV=1.0 MA=120 ns to the matched load. The output power of the 50 cavities is added with a MIVA, whose operation impedance is approximately matched to both source and load. Therefore, it has a nominal output capability of 4.5 MV=1.0 MA=120 ns to 4.5 Ω resistive load. The module is divided into five groups, and each group has ten cavities in series. The inner stalk of the MIVA is divided into five main straight segments. Conical transitions are employed to connect adjacent straight segments. The output end of M-50 is shrunk and connected a ring-cathode diode, whose cathode and anode radii are identical to those of a 12-m-long transmission line in the fusion facility. In this paper, the general concept of the fusion accelerator, the physical design, engineering design and development progress of M-50 are described for the first time.
All-electric aircraft is a high-priority goal in the avionics community. Both increased reliability and efficiency are the promised implications of this move. But, thermal management has become a significant problem that must be resolved before reaching this goal. Electromechanical actuators (EMAs) are of special concern. Advanced analysis technologies such as the finite element method (FEM) and intelligent control systems such as field-oriented control (FOC) are being used to better understand the source of the heat and to eliminate as much of it as possible. This paper describes the nonlinear, lumped-element, integrated modeling of a permanent magnet (PM) motor used in an EMA. The parameters, including nonlinear inductance, rotor flux linkage, and thermal resistances and capacitances, are tuned using FEM models of a real, commercial actuator. The FOC scheme and the lumped-element thermal model are also described.
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