Tritium retention in tungsten exposed to intense fluxes of 100 eV tritons

Tungsten is a candidate material for the International Thermonuclear Experi mental Reactor (ITER) as well as other future magnetic fusion energy device s. Tungsten is well suited for certain fusion applications in that it has a high threshold for sputtering as well as a very high melting point. As wit h all materials to be used on the inside of a tokamak or similar device, th ere is a need to know the behavior of hydrogen isotopes embedded in the mat erial. With this need in mind, the Tritium Plasma Experiment (TPE) has been used to examine the retention of tritium in tungsten exposed to very high fluxes of 100 eV tritons. Both tungsten and tungsten containing 1% lanthanu m oxide were used in these experiments. Measurements were performed over th e temperature range of 423-973 K. After exposure to the tritium plasma, the samples were transferred to an outgassing system containing an ionization chamber for detection of the released tritium. The samples were outgassed u sing linear ramps from room temperature up to 1473 K. Unlike most other mat erials exposed to energetic tritium, the tritium retention in tungsten reac hes a maximum at intermediate temperatures with low retention at both high and low temperatures. For the very high triton fluences used (>10(25) T/m(2 )), the fractional retention of the tritium was below 0.02% of the incident particles. This report presents not only the results of the tritium retent ion, but also includes the modeling of the results and the implication for ITER and other future fusion devices where tungsten is used. (C) 1999 Elsev ier Science B.V. All rights reserved.