Burial of 60 keV Deuterium Ions in Stainless Steel and Titanium

IN a controlled thermonuclear plasma it is necessary to minimize the entry into the hot plasma of low energy particles produced by the impact of fast particles on the walls of the container. These particles may be either particles of wall material or reflected incident particles. They can cool the plasma by two processes. The first process is a loss of bremsstrahlung radiation as a result of the interaction of atoms of high atomic charge from wall material with the fast electrons in the plasma. The second process of charge transfer between the atoms of the wall material and the energetic hydrogen ions in the plasma produces neutral hydrogen atoms which are subsequently lost to the walls. A study has been made of the burial of deuterium ions (D+) in stainless steel and titanium since these metals are commonly used in the construction of ultra high vacuum systems. The mechanisms of hydrogen trapping in these two metals differ considerably since a hydride can be formed with titanium but not with the elements in stainless steel.