Gas species, their evolution and segregation through the ITER vacuum systems

This paper takes the ITER fueling requirements and current knowledge of gas balance and exhaust from operating tokamaks to predict all likely gas inputs into the ITER Vacuum systems. Areas where gas dynamics modeling is relevant to the ITER design are highlighted. The design and operation of the ITER vacuum system gives an element of segregation of different gas flows and species. This paper analyses the time dependent gas segregation in the vacuum system resulting from different temperature dependences of cryogenic sorption and condensation processes of different gas species. As a specific example, the optimal transfer of 41Ar through the vacuum system is studied with respect to its decay and the resulting effects on the design of system components.

► The latest design of the ITER vacuum system is highlighted. ► Gas inputs and transformations are uniquely compiled. ► An analysis for 41Ar production and decay is given. ► The issues and use of gas dynamic modeling on ITER are outlined. ► Applications for future DSMC relevant to the vacuum system are given.