Beam Exit Vacuum System

Vacuum for the target chamber is supplied by an Alcatell 880 $\ell$/s Turbo pump backed by an Alcatell 21 $cfm$ 2 stage vane pump which maintains a $1x10^{-4}$ vacuum on the exit beam pipe.

Between the target chamber and the exit beam pipe there is a .007 $in$ kapton window that has a .0375 $in$ hole in it at the beam spot. This window acts as a differential pumping station.

Also between the target chamber and the exit beam pipe is an 8 $in$ air actuated gate valve that is operated from the MCC.

Vacuum readouts and interlocks outputs are supplied by an HPS 7 Series 275 mini Convectron and an HPS series 421 Cold Cathode gauge which are located near the balcony.

Controls are interlocked to the beam.

The chamber is made of a low mass aluminum corrugated vacuum tube of 1 $m$ diameter.

At the exit point of the exit beam pipe is a beam diffuser that consists of 2 .025 $in$ beryllium windows with a water filled cavity between them for cooling. The water is circulated through the cavity by a water cooling system located on the Hall floor, and is interlocked through the FSD system with 2 flow switches, one on the supply and one on the return line.

Due to high radiation levels at the exit beam pipe all seals in this area are metal.