PPT Slide
Laboratory model liquid metal jet target
Construction of a laboratory model liquid metal jet at CERN
(the item labeled lab model in the time-line transparency)
Our choice was between a pressurised liquid metal vessel with a fast gate valve controlling the jet - as used at UCLA, or a liquid metal pump either free running in pulsed mode or providing a closed-loop high-pressure line that could be opened by a fast valve - as used in several industrial processes for fluid handling and delivery (paint, wax, glue, etc.) The latter solution was chosen, although a fast gate valve (Valcor special development) for the first option is also being discussed.
The third transparency shows the layout of the model jet now being assembled at CERN. Tests with water will be performed during June.
Liquid metal eutectics have been prepared (Ga/Sn and Ga/In). Both have extremely good wetting properties. Ga/Sn developes an oxide scum. As the lab tests require visual observation of the jet, the observation windows must not become coated with metal. This has proved difficult. All transparent materials (glass, plexiglass, mylar, kapton, polystyrene, polycarbonate) are readily wetted and, surprisingly, coating the surfaces with silicone release agent gave no improvement - rather the contrary. A thin teflon film applied as a spray did significantly reduce the wetting. However, as we now firmly believe in the use of mercury in an operational target, we have chosen to use mercury also in the lab model. Tests with mercury are scheduled for July this year.