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

Kanemura, Takuji; Kondo, Hiroo; Hoashi, Eiji*; Suzuki, Sachiko*; Yamaoka, Nobuo*; Horiike, Hiroshi*; Furukawa, Tomohiro  ; Hirakawa, Yasushi ; Ida, Mizuho; Matsushita, Izuru*; Wakai, Eiichi  

In the Engineering Validation and Engineering Design Activities (EVEDA) project of the International Fusion Materials Irradiation Facility (IFMIF), thickness variation of a liquid lithium (Li) jet simulating the IFMIF Li target is to be measured in the EVEDA Li Test Loop. This paper presents fabrication and performance tests results of a contact-type liquid level sensor for measuring the jet thickness variation. The sensor can detect contacts between a probe and Li, and analysis of the contact signals yields average jet thickness and amplitude distribution. One of the key fabrication requirements is to drive the probe by 0.1 mm step with positioning precision of 0.01 mm under the vacuum condition of 10Pa. To achieve such requirements, a high torque motor reducer and a friction-reduced ball screw were selected. As a result of the performance tests, the measurement results of the positioning resolution and precision were 0.1 mm and 0.01 mm, respectively.