There are times when technological or scientific progress is blocked for want of a breakthrough in a key area, just as there appear to be instances of a problem and its solution emerging simultaneously and independently. Upon closer inspection, however, this latter happy state is usually the result of long, hard work by people who had the insight to develop a solution before their peers were aware of the existence of a problem. At the moment, there are a number of convergent events occurring in vacuum technology which in all likelihood will have as profound an effect as the development of ultrahigh vacuum (UHV) technology in the late 1960s and early 1970s. These developments may be viewed as challenges posed by the requirements of certain technologies, or as a series of breakthroughs which will lead to new opportunities. Materials and materials processing or coatings are the key factors in most of these new developments, just as new pump and seal designs, and new vacuum practice were responsible for the development of UHV (10−9–10−11 torr) technology.

In particular, aluminum is emerging as a material which may replace stainless steel for applications where the ultimate in vacuum is required. By suitable treatment, pure aluminum and aluminum alloys can be made to produce static outgassing rates more than 10 times lower than stainless steel. Systems capable of reaching a base pressure in the extremely high vacuum (XHV) range of 10−12–10−13 torr, such as those described in this issue by H. Ishimaru, are now commercially available.