Historical perspective of vacuum system application at the Nevada Test Site

Abstract

From the beginning of nuclear-device testing at the Nevada Test Site (NTS) in 1951 to the present, the U. S. Nuclear weapons laboratories have used high-vacuum environment in a wide range of applications. Nuclear measurement and diagnostic devices used in the test procedures require vacuum levels from 10−1 to less than 10−7 Torr. Researchers also need these vacuum levels to control the experimental environment when they study the effects of nuclear weapons on materials, devices, structures, or weapon system components. To produce the required vacuum environments in volumes up to 107 ℓ, researchers have used the following pumping systems: simple pumping apparatus, such as oil-sealed, rotary-vane mechanical pumps (pumping speeds as low as 2 ℓ/s); conventional, multistage, cascade pumping arrangements of oil diffusion, Roots blowers, and high-speed mechanical pumps (pumping speeds greater than 100 000 ℓ/s); and state-of-the-art, high-speed cryogenic, sputter-ion, turbomolecular, and evaporable or nonevaporable getter pumps (pumping speeds from 10 to more than 30 000 ℓ/s). More often, these pumping systems are remote from their operational control points. This paper describes these high-reliability vacuum systems and their engineering, design, and fabrication.