Simulation of Structure Stresses of Welded Cooling Channels at a Superconducting Magnet.

The housing of the superconducting magnet to be used in the Large Coil Task project of Euratom has welded cooling channels. The stresses in the welding seams based on the temperature differences between the cooling channel system and the housing wall have been estimated. The stresses influence the helium tightness of the system (5 multiplied by 10** minus **7 mbar 1/s), therefore the tightness check has to be made taking in account the structure stresses. The operation temperature of the magnet is 4. 2 K, so several possibilities for a tightness check are compared. The most successful method for the whole cooling system is shown to be the use of compressed gas. The applied simulation can also be used for other operation temperatures.