Wave period of free-surface waves on high-speed liquid lithium jet for IFMIF target

Wave period of free-surface waves on a high-speed liquid lithium (Li) jet has been experimentally studied for validation of a Li target of the International Fusion Materials Irradiation Facility (IFMIF), since stability of the jet is of crucial importance for generating high neutron fluence and for the safety of IFMIF itself. The experiments were conducted at a Li loop in Osaka University. In this loop, a plane Li wall jet of 70 mm in width and 10 mm in depth simulating the IFMIF Li target can be tested at the velocities of up to 15 m/s at the operation temperature of 573 K. In measurement of the wave period, the contact type liquid level sensor was used. As a result, probability density distribution of the wave period was found to be very similar to the log-normal distribution. From our previous and the present results, it is concluded that random wave property developed for the ocean waves can apply to the free-surface waves on the Li jet, irrespective of difference in the materials properties of Li and water.