Engineering design of contact-type liquid level sensor for measuring thickness validation of liquid lithium jet in IFMIF/EVEDA lithium test loop

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

In the Engineering Validation and Engineering Design Activities (EVEDA) project of the International Fusion Materials Irradiation Facility (IFMIF), which is one of the Broader Approach (BA) activities, thickness variation of a liquid lithium (Li) jet simulating the IFMIF Li target is planned to be measured in the EVEDA Li Test Loop (ELTL). For this purpose, a contact-type liquid level sensor was developed, which can detect contacts between a probe and Li. Analysis of the contact signals yields average jet thickness and amplitude distribution. One of the key development requirements is to drive the probe by 0.1 mm step with positioning accuracy of 0.01 mm under the vacuum condition of 10Pa. To satisfy such a requirement, the sensor's own weight load and moment load were calculated, and based on those calculation results a powerful motor and a friction-reduced ball screw were selected and strong structure was adopted. We have successfully completed the design work of the sensor.