抄録
Effect of FRP spacers on breakdown phenomena in liquid nitrogen in the presence of bubbles is investigated with a plane-to-cylindrical electrode. The interface between FRP spacers and liquid nitrogen was arranged at shortest gaps in electrode system. Bubbles were produced by a heater mounted in the cylinder for simulation of insulation circumstance in a state of quench. The experimental results show that thermal-bubble generation site at initial stage of boiling concentrates around contacting points of FRP and cylinder, and that the concentration of bubbles reduces breakdown voltage. Even if no boiling occurs, bubble produced by previous events and trapped near the interface causes the drastic reduction in breakdown voltage.
