Fabrication and performance test of contact-type liquid level sensor for measuring thickness variation of liquid lithium jet in the IFMIF/EVEDA lithium test loop

•We have fabricated a new sensor for measuring a liquid lithium jet thickness.•The design requirement is to position a probe with a high precision of 0.01mm.•The performance test result showed the sensor satisfied the design requirement.•It was found the precision of probe position calibration was high enough (44μm). In the engineering validation and engineering design activities (EVEDA) on the International Fusion Materials Irradiation Facility (IFMIF), hydraulic stability of a liquid Li jet simulating the IFMIF Li target is to be validated in the EVEDA Li test loop (ELTL). This paper presents the fabrication and performance test results of a new contact-type liquid level sensor designed for use in ELTL. The sensor is to be utilized to measure variation of jet thickness in the validation test on hydraulic stability of the Li jet, which is one of the major key tests to be performed in ELTL. A fundamental requirement for the engineering specification of the sensor is to ensure the positioning precision of the measurement probe against the pressure load of approx. 0.1MPa between the inside and the outside of the test chamber. The positioning resolution of 0.1mm and precision of 0.01mm with respect to the fluid-depth direction are the most important design requirement. The sensor was successfully fabricated as designed. The performance tests performed after fabrication shows that the sensor satisfies the design specification.