 |
 |
 |
Abstract. High-energy charge exchange particles bombarding the plasma facing wall may cause not only surface sputtering but also damage inside the materials due to its rather high energy. In the case of burning plasma, we should take into account the effects of helium because it is well known that helium atoms have much stronger effects on material damage than hydrogen atoms. In the present work, therefore, microscopic damage of metals exposed to long pulse discharges of helium plasma in TRIAM-1M was studied and discussed the impact on the hydrogen recycling process by comparing with the helium ion irradiation experiments. Considerably larger amount of dislocation loops and very dense fine bubbles were formed. Formation of bubbles has not been observed in hydrogen plasma discharge. According to the irradiation experiments with low energy helium ions, formation of dense helium bubbles drastically enhances hydrogen trapping and makes the desorption difficult. The preset result indicates the hydrogen recycling phenomenon during the burning plasma discharge must be quite different from that of the hydrogen plasma discharge experiments.
IAEA 2003
