chapter  7
Gases
Pages 4

Two topics that logically follow a chapter on gases are included here, namely, the recirculation of gases used to form beams and the levitation of solids. This was originally undertaken with gas beams, but we take liberties with the chapter title by including other methods that may prove useful for atomic beam production. Details of the vacuum systems in which the beam is produced, such as pumping and differential pumping, have not, in general, been included when discussing experiments, since these tend to be closely associated with the experiment for which the beam is required. Neither have general vacuum techniques been discussed, since these are covered in the many textbooks devoted to them. We nevertheless include details of methods that have been or could be used to recycle gases used in atomic beam experiments, since these tend not to be included elsewhere. It is also not our practice to discuss atomic beam applications such as those that are covered by the review articles referred to in Section 1.2, but we make an exception for levitation by atomic beams, since we are not aware of any review that includes these. We then add other levitation techniques that might prove useful for producing beams of refractory metals.