Direct force on electromigrating hydrogen isotopes

The present understanding of the magnitude of the direct force on hydrogen and its isotopes deuterium and tritium is discussed in the light of new experimental data and existing theoretical formulations. By this it is proven, that the direct valence of hydrogen can be significantly different from the unscreened jellium value of unity. Furthermore, a more detailed interpretation of a resistivity dependent direct valence is given, which clarifies the controversy around that subject. Selfconsistent calculations of the electronic charge density at and around an interstitial, at all positions along its electromigration jump path, are required to come to a more complete understanding of the measured results.