Roots Blower
The roots blower is used for initial pumpdown to ~ 0.1-1 mtorr, and serves as a backup to keep the vessel pressure low in the event of a significant leak from a cracked window, melted o-ring, damaged bellows, or partly opened valve. The roots blower must be turned on in order to enable hot-wall mode, which enables the heater interlock. In hot-wall mode, the gate valve to the roots blower will automatically open if the vessel pressure exceeds X Torr. It should not be turned off while lithium covered shells exceed the melting temperature of lithium, 180 C. It is powered by a 208 V three-phase feed and is backed by an oil-sealed rotary pump. The test cell is very noisy when the roots blower is operating and hearing protection should be worn.
