TECHNICAL INFORMATION
Fig. 16 - Typical installation
INLET FLANGE CONNECTION
The pump should be mounted allowing a sufficient
clearance for installation and removal of the high
voltage connector.
To achieve good performance of the ion pump at
low vacuum pressure, it is critical that atmospheric
pollution and dust must not enter the pump during
venting. This type of contamination will not be re-
moved by the standard high temperature bake
procedure and may degrade ion pump perform-
ance. The pump should be kept sealed with its
pinch-off tubulation until it is ready for attachment
to the vacuum system. Before venting the pump,
consult the inspection procedure (see preceding
paragraph).
Vent the ion pump by opening the pinch-off tubula-
tion in a clean area free from smog, dust, pollen,
etc. Venting with dry nitrogen gas is further rec-
ommended. This can be done by placing a clean
polyethylene bag over the ion pump flange. Small
pumps can be placed inside of the bag. Purge the
bag with clean, dry nitrogen for several minutes,
then reach into the bag and release the internal
vacuum using pliers to open the copper tube
pinch-off.
CAUTION
Do not open the pinch off-seal with a saw or
grinder. These methods will cause metal particles
to be drawn into the pump by the inrushing air as
the pump is opened.
,
WARNING!
The pinch-off seal is extremely sharp. Be careful
when opening. Watch your fingers.
Use appropriate procedures to maintain the clean
condition of the pump and vacuum system.
Unscrew the main flange bolts. Remove the Con-
Flat flange and the copper gasket plate. Some par-
ticles of copper oxide may adhere to the outer
edge of the flange gasket. Be careful not to allow
them or any other foreign materials to fall into the
pump.
Connect the ion pump to the vacuum chamber
with a short length and large diameter tubulation in
order to retain as much pumping speed as possi-
ble. Proceed as follows:
1. Inspect the mating flanges for cleanliness and
absence of scratches on the knife edge.
2. Place a new copper gasket between pump
flange and vacuum chamber flange.
3. Bolt mating flanges of the pump to the chamber
with the screws provided with the ion pump.
For flanges over NW 35 (2.75" o.d.) also mount
washers below the nuts and screw heads.
NOTE
Lubrication is essential to prevent galling of the nut
and screw after bakeout.
15
87-900-106-01(B)
