The rod pinch diode (RPD) is a cylindrical pinched beam diode that generates intense pulsed bremsstrahlung X-ray radiation with a small diameter. In practice, the anode and cathode structures of the RPD may be eccentric due to the mechanical deformation and mounting errors. In theory, this eccentricity changes the physical characteristics of the RPD, which in turn affects the X-ray production. To study the performance variation induced by eccentric electrodes, the electrode concentricity evaluation system is used to quantify the concentricity of the anode and cathode. Then a series of experiments are carried out with different concentricity deviations, and the electrical performance, the radiation dose, and the X-ray pulse signal among different shots are analyzed. These results have shown that, within a certain eccentricity range, the overall performances of the RPD, including the diode impedance and the X-ray production, change very little. Going beyond this range, the average impedance decay rate increases significantly, resulting in accelerated impedance collapse and shortened voltage pulse width. Consequently, X-ray dose distribution and the X-ray pulse width are both reduced. These results are helpful in understanding the RPD characteristics from a different perspective as well as providing a method to determine the designing and mounting criteria of the electrodes of rod-pinch diode.
Light initiated multi-gate semiconductor switch (LIMS) is a kind of power electronic device which has many differences from traditional thyristor triggered by electric pulse. LIMS is triggered by laser, the turn-on time is smaller, and the anti-electromagnetic interferences is strong. The opening mode of LIMS is obviously different to traditional thyristor. After the laser into the gate area, a large number of electrons and holes will appear in P-base region, holes gather in the area of P-base in PN junction J2, and electrons gather in N-drift region around the PN junction J2. PN junction J2 will open first, then PN junction J3 opens. The delay time of the NPN and PNP thyristors is close to zero when the laser pulse is narrow and the peak power is high, so the turn-on velocity is fast. To optimize the characteristics of the LIMS at high temperatures, we propose a new structure of the LIMS with the optimization of the n+ layer, circular light gate, and the new-style edge termination. The diameter of the LIMS is 23 mm. The experiment results show that the leakage current of the proposed LIMS has been decreased from more than 1 mA to 500 μA at 125 °C, the output current of the LIMS is 10.2 kA with a voltage of 4 kV at 85 °C, and the output current of the LIMS is 12.1 kA with a voltage of 4 kV at − 55 °C. Additionally, di/dt is larger than 30 kA/μs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.