최성민 교수

A voltage measurement system based on the Pockels electro-optic effect typically has, due to a half-wave voltage Vπ of a Pockels cell, a limitation on the unambiguous measurable range. To overcome such a limitation, we develop a polar-coordinate-based data analysis scheme with a simultaneous measurement of cos(π V/Vπ) and sin(π V/Vπ), where V is the voltage the Pockels cell experiences, i.e., the voltage we wish to measure. The developed data analysis scheme also corrects, without knowledge of V

Having a sub-ns response time and not requiring physical contacts to the measurement points, a voltage measurement system based on the Pockels electro-optic effect, referred to as a PE (Pockels effect)-based voltmeter, is widely used for pulsed high voltage devices such as accelerators and X-pinch systems. To correct for the misalignment of a Pockels cell and the transmittance ratio of a beam splitter, a polar-coordinate-based data analysis scheme has been proposed. This scheme also overcomes a

Abstract A diagnostic system using the Pockels effect (linear electro-optic effect) has been developed to measure a voltage on a load of the SNU X-pinch device [Ryu et al., Rev. Sci. Instrum. 92, 053533 (2021)]. The sensor component of the diagnostic system comprises of a lithium niobate (LN) crystal and its mount. When the LN crystal is subjected to an external electric field, the refractive indices of the LN crystal change due to the Pockels effect, leading to a change in the polarization stat

Optics-based measurement systems have been developed to measure the voltage and the current on a load of the Seoul National University X-pinch device [Ryu et al., Rev. Sci. Instrum. 92, 053533 (2021)]. A lithium niobate crystal that changes the polarization state of the propagating laser beam due to the Pockels effect induced by the electric field across the crystal, thus capable of measuring the voltage, is located next to the load. For the current measurement, an optic fiber is wound around th

Neutron science and technology, the utilization of neutron beams for a wide variety of scientific and engineering research ranging from materials and life science to industrial applications, has been one of the key elements of modern science and technology. Currently, the neutron science and technology in Korea is in rapid growth with the operation of the 30 MW High-flux Advanced Neutron Application Reactor (HANARO) at the Korea Atomic Energy Research Institute, which is one of the most powerful

This study investigates the characteristics of X-pinch plasmas driven under low current rise rate ($dI/dt$) conditions using soft x-ray spectroscopy combined with the Bennett relation. X-pinch experiments were conducted on the SNU X-pinch device using copper wires at a low $dI/dt$ of 0.2-0.3 kA/ns. The resulting 1-10 keV soft x-ray signals, measured by an x-ray filtered AXUV photodiode array (XFPA), exhibit significant nonlinear effects due to the high intensity of the soft x-ray pulses. This wo

Abstract A collective Thomson scattering (CTS) diagnostic system has been commissioned to measure the ion features of the jet plasma region of X-pinch plasma, including electron temperature, ion temperature, electron density, average charge state, and plasma bulk velocity. Due to the inherent nature of CTS, signals with two peaks within a very narrow wavelength range are observed, depending on the ion motion. To analyze CTS signals, a spectrometer with a high dispersion and high resolution is re

This study investigates the characteristics of X-pinch plasmas driven under low current rise rate ($dI/dt$) conditions using soft x-ray spectroscopy combined with the Bennett relation. X-pinch experiments were conducted on the SNU X-pinch device using copper wires at a low $dI/dt$ of 0.2-0.3 kA/ns. The resulting 1-10 keV soft x-ray signals, measured by an x-ray filtered AXUV photodiode array (XFPA), exhibit significant nonlinear effects due to the high intensity of the soft x-ray pulses. This wo