Hydrogen Trapping Studies in Fusion First Wall Materials
Hydrogen trapping in the first wall of fusion reactors is one of the most serious materials problems facing the designers of magnetic confinement devices. The release of this trapped hydrogen from the near surface region of the first wall during a tokamak discharge has been shown to play a major role in the hydrogen fueling of today's plasmas, while trapped hydrogen isotopes will directly influence the on-site tritium inventory and the structural properties of future D-T reactors. This paper summarizes the laboratory ion implantation sttidies on the hydrogen trapping characteristics of first wall materials. Emphasis is placed on the near term materials problems associated with austenitic stainless steels that are currently in use in magnetic confinement devices. Hydrogen trapping experiments involving more exotic first wall structural and coating materials are briefly reviewed.
Liberation of deuterium gas from molybdenum upon heating after penetration of D+ ions
ConclusionA series of peaks of liberation of deuterium gas from molybdenum has been discovered in this paper upon the heating of a sample after ion penetration. The maxima of these peaks lie, in the 230–650°K range. The diffusion coefficient and the activation energy in the individual peaks of j(T) have been measured. It has been discovered that D in the individual peaks covers a range of at least 10 orders of magnitude when the temperature is constant, and the discrete activation energy series comprises 45–126 kJ/mole. The measured values of D and Q can be larger or smaller than those which are measured in experiments on hydrogen transport. At high irradiation doses an interrelationship has been discovered in the first group of peaks between secondary defects in molybdenum and the liberation of captured deuterium gas. It is suggested that secondary defects can serve, in different cases both as centers for deuterium retention and as the means for its easier escape to the surface. It has been assumed possible to explain the high-temperature peaks as the release of deuterium from radiation vacancy-deuterium atom complexes with a different content of vacancies and deuterons.
Finite Difference Modeling on the Temperature Field of Substrate in Friction Surfacing
Friction surfacing is an advanced process of great potential, especially in the field of repair and reclamation of worn and damaged components. As a kind of thermal processing technology, the temperature profile and changes of the substrate in friction surfacing are important factors to get coatings of high quality. In this paper, the temperature field of the substrate during the process is simulated by finite difference method. The results are consistent with experiments, reappearing the temperature change of the substrate during friction surfacing, allowing further study on figuration and quality of coatings.