Proposal for a helium cooling system for beam foil windows

Thin metal foil windows can be used to isolate the target from the beam line in such a way that very little degradation of the beam takes place. The heat dissipated in these windows should be removed sufficiently to keep their operating temperatures well below melting point. Water cooling of the window edges can be provided but is usually insufficient. Additional cooling can be provided by blowing a suitable cooling gas (usually helium) across the window surface and this technique can best be implemented by using double foil window systems and by blowing the cooling gas through the space between the two foils. A summary of relevant publications is given with the emphasis on windows in different target designs, window strength and helium cooling systems. An experiment is also performed to determine the cooling power densities of helium at room temperature and an average pressure of 1 Atm. for different surface temperatures. The design of a possible helium cooling system for the Radioisotope Production Division is shown