Operating Notes; Technical Specification - Varian 919-0520 Manuel D'instructions

OPERATING NOTES

VacIon pumps operate as a single-cell Penning
discharge. A potential of about 3 kV is applied to
the anode cell; the cathodes are at ground
potential. Electrons are constrained from going
directly to the anode by the presence of an axial
magnetic field of about 1200 gauss. A self-
shielding insulator isolates the anode from ground
potential. When the VacIon pump is operating
properly (with magnet installed), the current drawn
is proportional to pressure (see the figure in the
following page).
After the system is rough-pumped to below 10
mbar, the pump can be started by simply switching
on the VacIon pump control unit. A current draw on
the control unit will indicate that the pump
discharge has started.
The pump can operate in any position and can be
supported on the mounting flange.
NOTE
Always wait at least 30 seconds after turning off
the high voltage switch before disconnecting the
power supply leads. This should allow the power
supply output capacitor to discharge adequately.

TECHNICAL SPECIFICATION

The following table details the main technical
specifications of the 2 l/s Ion Pump.
Nominal pumping speed for Nitrogen
(l/s)
Operating life at 5x10
(hours)
Operating voltage
Maximum starting pressure
(mbar)
-4
Ultimate pressare
(mbar)
Internal volume
(litres)
Maximum baking temperature
(°C)
Material:
Weight,
lbs (kg)
Pressure vs Current curve
10
TECHNICAL INFORMATION
2
-6
mbar 8000
+3300 Vdc
+/- 10%
1x10
(with MicroVac
control unit)
10
0.064
400 (without magnet)
150 (with magnet)
Body AISI 304
Cathode Titanium
Anode AISI 304
Magnet Sm-Co
0.66 (0.3) net
1.33 (0.6) with
magnet
87-900-091-01(B)
-4
-9