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where:
❑
I
is the ion current in amperes to the collector,
c
❑
I
is the electron current in amperes to the grid, and
e
❑
P is the pressure in Torr.
The sensitivity, S, of a given ion gauge is the proportionality constant in the basic
ionization gauge equation above. Thus,
For UHV-24 gauges, S for air (nitrogen) is 25 (Torr)
-1
20 (Torr)
. The normal operating electron current is 4 mA. For the UHV-24, the ion current
at a pressure of 10
Installation
Agilent ionization gauges can be operated with any ion gauge control unit capable of
supplying the necessary operating voltages and currents. Degassing of this gauge is by
electron bombardment of the grid.
To install the gauge:
1. Remove the metal sleeve protecting the collector wire.
2. Mount the nude ionization gauges in any position.
12
UHV-24/UHV-24p Ionization Gauge
-9
-10
Torr is 10
A.
NOTE
Install the gauge in a relatively open space to reduce wall
outgassing due to localized heating by the filament.
When the gauges are mounted horizontally, position the
filaments to the side of the grid rather than below or above it so
that a slight vertical movement of the grid or filament does not
change their relative spacing.
I
1
c
S
=
-- -
--- -
P
I
e
-1
. For the UHV-24p, S for air (Nitrogen) is
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