AML NGC3 User manual

NGC3 Ion Gauge Controller
UHV Dual Bayard-Alpert Ion Gauge Controller
USER MANUAL
ISSUE 20200326
For use with firmware version 7.x.x

1. Introduction .................................................................................................................................................................... 5
1.1. Scope of this manual.................................................................................................................................................................................................................5
2. Technical data................................................................................................................................................................. 6
2.1. Mechanical Data .........................................................................................................................................................................................................................6
2.2. Electrical Supply..........................................................................................................................................................................................................................6
2.3. Environment.................................................................................................................................................................................................................................6
2.4. Electrometer.................................................................................................................................................................................................................................6
2.5. Ion Gauge......................................................................................................................................................................................................................................7
2.6. Pirani Gauge.................................................................................................................................................................................................................................7
2.7. Active Gauge................................................................................................................................................................................................................................7
2.8. Process trips .................................................................................................................................................................................................................................7
2.9. Bake-out ........................................................................................................................................................................................................................................7
2.10. Communications.........................................................................................................................................................................................................................7
3. Warnings and safety ...................................................................................................................................................... 8
4. Installation....................................................................................................................................................................... 9
4.1. Instrument installation..............................................................................................................................................................................................................9
4.2. Ion Gauge-head installation..................................................................................................................................................................................................11
5. Front panel .................................................................................................................................................................... 12
6. Setup .............................................................................................................................................................................. 13
6.1. Switching on...............................................................................................................................................................................................................................13
6.2. Setup, General description ....................................................................................................................................................................................................13
Password/Units..........................................................................................................................................................................................................................13
Ion Gauge Mode.......................................................................................................................................................................................................................14
Gauges .........................................................................................................................................................................................................................................17
Relay assignment......................................................................................................................................................................................................................19
Bake...............................................................................................................................................................................................................................................19
Degas............................................................................................................................................................................................................................................20
7. Operation....................................................................................................................................................................... 21
7.1. Use of the Function Switch in the operating positions ................................................................................................................................................21
7.2. Relay trip levels .........................................................................................................................................................................................................................21
7.3. Display sequence when the function switch is in the OFF position .........................................................................................................................22
Pirani.............................................................................................................................................................................................................................................22
Active Gauge..............................................................................................................................................................................................................................22
IG Sensitivity...............................................................................................................................................................................................................................22
Leak Detector.............................................................................................................................................................................................................................23
Temperature...............................................................................................................................................................................................................................23
Instrument ID.............................................................................................................................................................................................................................23
8. Ion Gauge operation.................................................................................................................................................... 24
8.1. Display sequence when Ion Gauges are in emission ....................................................................................................................................................24
Starting the Ion Gauge............................................................................................................................................................................................................24
Manual Emission Change.......................................................................................................................................................................................................25
8.2. Changing Ion Gauge emission .............................................................................................................................................................................................25
8.3. Prompted emission change ..................................................................................................................................................................................................25
9. Degassing ...................................................................................................................................................................... 26
Manual Degas............................................................................................................................................................................................................................27
Programmed Degas.................................................................................................................................................................................................................27
Quick Degas ...............................................................................................................................................................................................................................27
10. Bake................................................................................................................................................................................ 28
11. Recorder Output........................................................................................................................................................... 29
12. External inhibit ............................................................................................................................................................. 29

13. Windows Software ....................................................................................................................................................... 30
14. Remote operation ........................................................................................................................................................ 30
14.1. Introduction................................................................................................................................................................................................................................30
14.2. Interface protocol.....................................................................................................................................................................................................................30
14.3. Local/remote control...............................................................................................................................................................................................................30
14.4. Host Computer Commands ..................................................................................................................................................................................................31
14.5. NGC3 Response ........................................................................................................................................................................................................................31
14.6. Timing of Next Command .....................................................................................................................................................................................................31
14.7. State & Error byte coding......................................................................................................................................................................................................31
14.8. Host Computer Command Characters ..............................................................................................................................................................................32
14.9. <status> Status report............................................................................................................................................................................................................33
15. Troubleshooting ........................................................................................................................................................... 34
15.1. Fan slow / failed........................................................................................................................................................................................................................34
15.2. Temperature...............................................................................................................................................................................................................................34
15.3. Emission Fault............................................................................................................................................................................................................................34
15.4. IG Fil O/C.....................................................................................................................................................................................................................................34
15.5. Password forgotten?................................................................................................................................................................................................................34
15.6. Ion Gauge connections...........................................................................................................................................................................................................35
16. Assistance ...................................................................................................................................................................... 35
Appendix A Gauge Principles.................................................................................................................................... 36
A.1 Ionisation Gauges.....................................................................................................................................................................................................................36
A.2 Pirani Gauges.............................................................................................................................................................................................................................36
A.3 Capacitance manometers ......................................................................................................................................................................................................36

© Arun Microelectronics Ltd 2020. All rights reserved Page 5
1. Introduction
The NGC3 process controller is a high-accuracy Bayard-Alpert (BA) Ion Gauge controller that offers integrated pressure
measurement and process control. The controller operates from electrical supply voltages in the range 100 to 240 volts and
frequencies of 48 to 65 hertz.
The controller may be used with UHV Ion Gauges incorporating tungsten or coated iridium filaments. The controller can
operate two Ion Gauges sequentially, two AML Pirani Gauges and one Active Gauge-head via a standard RJ45 jack.
Four power relays for process control are provided as is an internal thermocouple amplifier for bakeout control.
1.1. Scope of this manual
This manual provides installation, operation and maintenance instructions for the Arun Microelectronics Ltd Ion Gauge
Controller model NGC3. Please read this manual before attempting to install and operate the controller.
This manual contains essential safety information which supplements the safety features of the controller. Safety
procedures are highlighted as WARNING instructions by the symbol below. Failure to observe the instructions could result
in injury or death to persons.

© Arun Microelectronics Ltd 2020. All rights reserved Page 6
2. Technical data
2.1. Mechanical Data
Dimensions
Width: 19″full-width rack (482.6 mm)
Height: 1U (44.45 mm)
Depth: 270 mm, excluding connectors
Weight
2.7 kg
2.2. Electrical Supply
Supply voltage
100 to 240 volts nominal at 48 to 65 hertz, auto-adjusting
Power consumption
Less than 20 W idle
90 W maximum
Fuse
2.0 A, 250 V (T), 5 x 20 mm
Supply socket
IEC 320-C14
Overvoltage category
II
Protection class
1
2.3. Environment
Operating temperature
5°C to 35°C for specified performance
Operation is inhibited at greater than 40°C
Storage temperature
-10°C to 70°C
Relative humidity (non-condensing)
80 % for temperatures up to 31 °C, decreasing linearly to 50 % at 40 °C
Maximum operating altitude
2000 m
Pollution category –EN61010
1
Ingress protection
IP20
2.4. Electrometer
Logarithmic conformance1
Range
21°C
+5°C to +35°C
1 mA to 350 pA
<1%
<1%
<350 pA to 10 pA
<1%
<4%
<10 pA to 2 pA
<10%
<20%
1
Some reduction in performance may occur at 30 MHz to 1 GHz at high RF field strengths

© Arun Microelectronics Ltd 2020. All rights reserved Page 7
2.5. Ion Gauge
Suitable type
UHV Bayard-Alpert Gauges with coiled filaments
Range
1 x 10-3 to below 3 x 10-11 mBar. Dependant on gauge-head
Grid
+200 Vdc (+500 V at 60 mA in Degas)
Filament
Tungsten: ≤12 V at ≤4.2 A
Coated iridium: ≤12 V at ≤2.6 A
Filament power limited to >30 W
Filament bias: +50 V
Collector
0 V (virtual earth)
Emission current
Soft-start emission control at 0.5 mA or 5 mA
Sensitivity adjustment
1 mBar-1 to 140 mBar-1
2.6. Pirani Gauge
Suitable type
Constant-voltage, half bridge. Calibration at connector
Range
1 x 10-3 mBar to 200 mBar
2.7. Active Gauge
Suitable type
Self-powered or active gauge with +10 V full-scale output.
Format selectable between linear (1, 10, 100, 1000 mBar or Torr full
scale) or log (1 V/decade, 0.5 V at 1E-6 mBar)
The instrument provides a regulated +24 Vdc supply, 1.0 W maximum,
protected by a 50 mA self-resetting fuse to power a connected active
gauge.
2.8. Process trips
Relays
4 x single-pole, change-over. 5 A at 240 V maximum
Assignment
Independently assignable to any gauge
2.9. Bake-out
Thermocouple type
Mineral-insulated K-type with miniature flat-pin connector
Programme
Settable bake temperature (50°C to 250°C), bake time (1 hour to 90
hours) and overpressure limit
2.10. Communications
Interface
RS232C
Settings
1200, 2400, 4800 or 9600 (Default) baud,
8 data bits, 1 stop bit, no parity, no handshaking

© Arun Microelectronics Ltd 2020. All rights reserved Page 8
3. Warnings and safety
WARNING –Safe operation of Ion Gauges requires grounding of all exposed
conductors of the vacuum system, gauges and controller. LETHAL VOLTAGES may be
established under some operating conditions unless correct grounding is provided. All
exposed and isolated metal parts should be reliably grounded to a common system
earth point via 4 mm2or thicker copper wire/braid, the integrity of which should be
checked regularly. No ferrite components should be installed.
High voltages are present within the instrument when operating and for some seconds after switching
off. Remove the mains lead before removing the cover for any reason.
Ensure that maintenance is carried out only by suitably trained personnel.
Voltages up to 500 V in degas and 200 V in normal operation are present on the IG cable when the IG is
on. Voltages up to 600 V are present within the instrument.
•This manual must be consulted in all cases where the warning symbol (shown above, left) appears on the
instrument.
•The safety of any system incorporating the instrument is the responsibility of the assembler of the system.
•Use the instrument only as specified in this manual, or the protection provided by the instrument might be
impaired.
•The mains lead must be adequately rated for the instrument.
Instruments are shipped with password protection disabled. If you set a password you must record what it is.
The conditions set at manufacture assume that you do not require any interlocks and that the Ion Gauges have a tungsten
filament. You may fuse coated Ion Gauge filaments if you do not set up the instrument appropriately.
Allow several minutes for Pirani Gauges to reach operating temperature after switching on before using them for interlock,
autostart or process control.
Two fans are used sequentially for cooling. Orange status LEDs on the front panel indicate which fan is being used. If a fan
fails a message is displayed at the time of failure and the LED for that fan flashes thereafter. Operation with only one fan is
permissible but the faulty fan should be replaced as soon as possible. If the remaining fan fails, operation of the Ion
Gauges will be disabled. Replacement fans must conform to the specification printed on the rear panel and are available
from AML.
Discharges from X-ray power supplies and other high-voltage and high-energy sources (which are commonly used in
vacuum systems) into the Ion Gauge may damage the instrument. Such damage is not covered by the warranty. Discharge
damage will be minimised by decreasing the impedance of the strap/cable from the earth stud on the instrument to the
vacuum system earth distribution point. This connection may also be essential for operator safety: follow the safety
instructions and recommendations of the supplier of any high-voltage equipment used in the vacuum system.

© Arun Microelectronics Ltd 2020. All rights reserved Page 9
4. Installation
Checks on receipt of the instrument
On receipt of the instrument remove all packing material and check that all items on the shipping list have been received.
Report any damage or shortages to the Company or the Distributor who supplied the instrument. The packing material has
been specifically designed to protect the instrument and should be retained for possible future use.
4.1. Instrument installation
Mounting
The instrument is suitable for mounting in a standard 19″rack and occupies 1U (1.75″, 44.45 mm) of the rack. The
mounting holes in the front panel are intended for retaining the instrument in the rack and will not support its weight.
Additional support is required toward the rear and various arrangements are provided by rack manufacturers for this
purpose.
Cleaning
If the instrument requires cleaning, wipe it down with a cloth slightly dampened with water or a mild detergent.
Ventilation
The instrument is forced air ventilated through grilles on the sides and a vent in the rear panel. Mount it in a location where
there is an adequate supply of air as close as possible to cool room ambient temperature. The instrument is tolerant of
and is compensated for operation at elevated ambient temperatures up to 40°C. Long term accuracy and reliability will be
enhanced by operation at the lowest possible temperature, within the operating temperature range. If there are other
instruments in the rack which generate significant amounts of waste heat, try to ensure that this is deflected away from this
instrument.
Line Power Connection
The NGC3 operates from a 100 to 240 volts nominal AC power source having a line frequency of 48 to 65 Hz. Use a three-
wire power cord to connect to a properly grounded wall outlet.
Line Fuse
There is a line fuse (Rating: 2.0 A, 250 V, (T)) located on the inside of the instrument on the rear of the power inlet
connector.
High voltages are present within the instrument when operating and for some seconds
after switching off. Remove the mains lead before removing the cover for any reason.
The top cover is connected to the enclosure with a wire to ensure earth continuity. Do
not remove this wire, ensure it is intact before replacing the lid, taking care to avoid
pinching the wire between the lid and enclosure base.
Grounding
The instrument earth stud (right side when viewing the rear panel, and identified by the
symbol) must be connected directly to the vacuum system earth distribution point with
a low-impedance strap/cable (≥4mm2or ≤12 AWG). There must be no ferrite
components installed on it.

© Arun Microelectronics Ltd 2020. All rights reserved Page 10
Ion Gauge 1 & 2
Use AML-approved gauges with properly-screened leads. The ground braid of the Ion
Gauge cable must be connected to the instrument ground stud.
Ion Gauge leads should not be installed close to cables carrying high alternating
currents or through areas where there are significant alternating magnetic fields. They
should be constrained, since movement or vibration will generate charges or currents
and these may disturb UHV pressure readings.
Third-party Ion Gauge cables may not allow compliance with EU EMC Directives and
may lead to unstable emission. As a minimum, there must be an overall screen on the
lead and an inner screen on the collector connected to the BNC shell. These screens
must not connect either to the vacuum chamber or to each other. Interlock pins 1 & 3
must be connected together.
Pirani 1 & 2
AML Pirani Gauges PVU and PVB are suitable for use with this instrument. Pirani 1
pressure may be used for Ion Gauge Interlock and Autostart functions and should be
installed in the same chamber as the Ion Gauge if used for this purpose. Pirani 2 is normally used for backing-line pressure
measurement.
Process control relays
The terminal block cover (supplied) must be fitted to restrict access to the terminals if
they are used with voltages greater than 24 V. Take appropriate action to strain-relieve
the wiring.
Four single-pole, change-over relays are provided for process control and can be independently assigned to any gauge.
Contacts are rated at 5 A, 240 V maximum. The contacts of the relays are shown diagrammatically on the rear panel legend,
in the de-energised condition, adjacent to the terminal blocks to which they are connected.
Inductive loads, including contactor coils, should have “snubber”networks connected in parallel to avoid arc generation
which could interfere with the operation of this and other equipment. The external wiring is connected to the instrument
through a two-part pluggable terminal block. This can be removed and wired independently of the instrument. Ensure that
external wiring is of adequate cross-section for the load current. Strip and twist the wires (do not tin them) and poke into
the receptacle in the terminal block. Close the leaf on the wire by tightening the screw immediately above. Take
appropriate action to strain-relieve the wiring nearby and to restrict access to the terminals if harmful voltages are to be
present. Fit the terminal block cover supplied.
If the Bake function is to be used then Relay D must be assigned to Bake. It is used to switch on the Bake heaters when
energised. Do not connect heaters directly to Relay D; use a contactor and fit a snubber directly across its coil. The pressure
measurement during the bake cycle is read from Ion Gauge 1 only.
Bake Thermocouple
The K thermocouple tip must be isolated from the vacuum chamber and situated where it accurately represents the Bake
temperature. Mineral-insulated thermocouples with a miniature flat-pin thermocouple connector should be used.
Figure 1 Ion Gauge
Connector pinout
1
Interlock
2
Grid
3
Interlock
4
Filament Common
5
Filament 1
6
Filament 2

© Arun Microelectronics Ltd 2020. All rights reserved Page 11
Auxiliary Connector
The Auxiliary (AUX) connector is a plug-in terminal block. Connect the recorder
between Recorder and 0 V (Refer to section 11). Connecting Ext. Inhibit to 0 V will
prevent Ion Gauge emission (Refer to section 12). A screened cable must be used,
with the screen connected to 0 V.
Active Gauge Connector
The Active Gauge connector is an 8P8C RJ45 jack. It is intended for connection of the
AML APG-1 MEMS Pirani Gauge, but other similarly low-powered Active Gauges may
be used. A screened patch cable must be used.
The connector provides a 24 Vdc supply, between +24 Vdc and PGND, protected by
an internal 50 mA self-resetting fuse. Do not use this supply for any other purpose.
Connect the gauge signal between the Signal and Signal GND
pins. Do not connect Signal GND and PGND, as measurement
errors may result. The input range is 0 –10 V.
The NGC3 displays the measured voltage as a pressure. There
are two selectable formats, log and linear (Refer to Section 6.2,
‘Gauges’). Additional formats can be accommodated if
required; contact AML for more information.
Active Gauge pressure may be used for Ion Gauge Interlock
and Autostart functions, as an alternative to Pirani 1.
Serial Connector
The serial interface is RS232-compatible and only one
instrument may be connected to each computer serial port
(a USB to RS232 serial adaptor may be required).
The connector is a 9-way “D” type female connector. The
pin numbering has been chosen so that a 9-way ‘straight-
through’ male-to-female cable will be satisfactory for use
with a PC serial port.
4.2. Ion Gauge-head installation
Consult the information supplied with the gauge-head for advice on flanges, gaskets and adaptors for mechanical fixing.
Mount the gauge-head in a position where the free electrons generated in its vicinity will not affect other equipment. The
performance of the Ion Gauge may be affected by other electron or ion generating processes within the vacuum chamber:
should shielding of the gauge-head be necessary, ensure that the conductance between the gauge-head and volume of
interest is not significantly decreased by its presence. The orientation of the gauge-head should be such that the filament is
to the side of, or below, the grid structure. This will ensure that if the filament should sag or break it will not short circuit to
the grid. The gauge and controller are protected from all normal failure modes of either.
Users should be aware of potential hazards from other equipment, particularly those introducing high voltages into the
vacuum chamber.
Figure 2 AUX Connector pinout
1
0 V
2
Ext. Inhibit
3
Recorder
Figure 3 Active Gauge socket pinout (RJ45)
1
+24 Vdc
5
Signal GND
2
PGND
6
NC
3
Signal
7
NC
4
NC
8
NC
Figure 4 Serial connector pinout
1
NC
6
NC
2
Tx
7
NC
3
Rx
8
NC
4
NC
9
NC
5
GND

© Arun Microelectronics Ltd 2020. All rights reserved Page 12
5. Front panel
The rotary Function Switch has two sets of positions: for setup and operating. The
SETUP locations are labelled in orange print. The switch must be stationary for a
brief period of time before any action results.
A set of status LEDs are situated in the Status Window. The LEDs on the right
side of the window show further information about operations involving the
Ion Gauges, such as the Degas program in use. The LEDs on the left side
indicate the status of the instrument, the fans and the number of the filament
and gauge in use.
Flashing of the display or of individual LEDs either require a response by the
user or indicate an error/fault condition.
INC, DEC and ENT are pushbutton switches with tactile
feedback. They select the format of pressure display, modify
setups and change parameters before and during Ion Gauge
operation. Only press one switch at a time.
The legends above and below the display window indicate the units and the exponent scale for
interpreting the bar graph displays of Ion Gauge pressure.
LEDs indicate the status of the
four relays available for
pressure-related and Bake
control. Each LED illuminates
when the associated relay is
energised.
The units of the pressure display are indicated by one of three LEDs in
the display area. The centre orange LED indicates that mBar has been
selected, the green LED above it indicates Pascal and the green LED
below indicates Torr.

© Arun Microelectronics Ltd 2020. All rights reserved Page 13
6. Setup
New users should explore and familiarise themselves with the use of the controls and displays before connecting any
gauges or wiring to the rear panel.
6.1. Switching on
Turn the Function Switch to the OFF position. Connect and switch on the mains supply and wait for the start-up messages
to clear (approx. 5 seconds). During this time, both fans are checked for correct operation. The last display in the sequence
will show Pirani 1 pressure or Active Gauge pressure (if enabled). Pirani Gauges take some time to stabilise before they
indicate correct pressure. If Pirani 1 is not connected the display will show ‘PG1 >200mB’. By default, if the Function Switch
is at a position calling for emission at switch-on, emission is inhibited and 'Switch Em Off' is displayed. See section ‘Ion
Gauge Mode’ for alternative modes of operation.
6.2. Setup, General description
Instrument settings are accessible by selecting one of the six SETUP switch locations. There is no restriction on when, how
many times, or in what order you can enter a particular setup.
You may move the Function Switch part-way through a sequence if you do not wish to modify subsequent settings within a
setup. For example, in SETUP →GAUGES you may change the filament in use without progressing through filament
material, overpressure, etc.
If the instrument is waiting for a response from you then part of the display will flash, indicating that a choice can be made,
or a setting edited. 󰵎and 󰵍modify the choice or setting and ENT confirms it. If you do not modify the displayed setting
for a few minutes the instrument will beep periodically. If you do not respond for a further few seconds then the current
display will be replaced by ‘Setup Aborted’ and the setting or choice at the aborted stage will revert to its former setting.
If you move the Function Switch after modifying a choice or value but have not confirmed it with ENT then the existing
choice or value is unchanged.
If you do not require Bake, it can be disabled by not assigning a relay to that function.
Setups and access to operating parameters and functions can be password-protected to prevent unauthorised use.
Password/Units
Set Password?
Press 󰵎or 󰵍to select if a password is to be used. Press ENT to
confirm.
If a password is to be used.
Change each character with 󰵎or 󰵍and confirm with ENT.
Select the units of pressure display (mBar, Pa or Torr). The
current selection will flash on the main display.
Press 󰵎or 󰵍to select 1 or 2 decimal places to be shown on
the Ion Gauge pressure display.
Select if gauge pressures greater than 1mB should be
displayed in scientific notation or decimal notation.

© Arun Microelectronics Ltd 2020. All rights reserved Page 14
Select ‘Yes’to assign a 3-7 character instrument ID.
Change each character with 󰵎or 󰵍and confirm with ENT. If
enabled this ID will be shown during start-up and is available
as an item in the main display sequence.
Select the baud rate. 9600 baud is the default for all AML
software.
Select ‘Yes’and confirm to return the instrument to its factory
default settings. All user settings will be lost.
Ion Gauge Mode
Select and configure the Ion Gauge mode. Four modes of operation are available; Interlock, Autostart, Manual and Ext.
Inhibit. Note that when starting emission remotely, either via the <Gauge on> command (see section 14.8) or the
supplied software (see section 13) the behaviour of the chosen mode still applies; therefore manual mode is usually the
best choice as this starts and stops the ion gauge immediately on command.
•The chosen mode applies to both Ion Gauge 1 and Ion Gauge 2.
•Regardless of the selected mode, the external inhibit signal on the AUX connector (see section 12) is always
respected.
•Only Interlock and manual modes have any function when running bake or degas. If any other mode is selected
when running bake or degas, the behaviour of manual mode applies.
•Any fault occurring in emission turns off the Ion Gauge, and the Function Switch must be returned to OFF
before another attempt can be made to start emission.
Manual mode
Ion Gauge starts immediately when Function Switch is turned to
an emission position.
•Ion Gauge starts when the Function Switch is turned
to an emission position, one of IG1, IG2, DEGAS or
BAKE.
•If the Function Switch is in an emission position when
the instrument is powered on, a warning message
appears and the Function Switch must be turned to a
non-emission position before startup continues.
•External inhibit is considered as a fault, with the same
behaviour as when a fault occurs in emission.
Interlock mode

© Arun Microelectronics Ltd 2020. All rights reserved Page 15
Prevents Ion Gauge from starting, or stops emission, if Interlock
gauge pressure is above a specified threshold, preventing restart
without user intervention.
The behaviour of manual mode applies, in addition:
•An Interlock gauge is selected, either Pirani 1 or the
Active Gauge.
•An Interlock pressure is specified.
•Ion Gauge is only allowed to start if the Interlock
gauge measures a pressure less than the Interlock
pressure at the time when the Function Switch is
turned to an emission position.
•If the Interlock gauge measures a pressure greater
than or equal to the Interlock pressure, then emission
is prevented from starting (if the Function Switch was
just turned to an emission position) or stopped
immediately (if emission was in progress) and a
warning message is displayed according to the
chosen Interlock gauge.
•Once in the Interlocked state, the Function Switch
must be returned to OFF before another attempt can
be made to start emission.
•If the Interlock gauge is not switched on (Pirani 1) or
not used (Active Gauge) then a warning message is
shown and emission cannot be started.
•If the Interlock gauge is Pirani 1, and Pirani 1 fails
open circuit, emission will be aborted if in progress, or
prevented from starting. This is considered a fault
condition, requiring the Function Switch to be
returned to OFF before another attempt can be made
to start emission.

© Arun Microelectronics Ltd 2020. All rights reserved Page 16
Autostart mode
Automatically start and stop IG1 or IG2 based on Autostart
gauge pressure. If Autostart criteria are met, start and stop IG1
based on external inhibit signal.
Only applicable to IG1 and IG2 Function Switch positions. In
BAKE or DEGAS Function Switch positions, the behaviour is as
Manual mode.
•An Autostart gauge is selected, either Pirani 1 or
Active Gauge.
•An Autostart pressure is specified.
•When the Autostart gauge pressure is less than the
Autostart pressure, the Ion Gauge will start
automatically.
•If the Autostart gauge pressure rises above the
threshold:
  󰇛 󰇜
Where is the Autostart gauge pressure and  is
the Autostart pressure, then emission is suspended
and the display alternates between showing the
Autostart gauge pressure and an Autostart warning
message. Emission will restart when the Autostart
gauge pressure falls below the Autostart pressure.
•External inhibit is not considered a fault. If external
inhibit is present, a warning message is displayed and
emission is suspended. Once external inhibit is
removed and Autostart gauge pressure is below the
Autostart pressure, emission will resume.
•Functions at startup. If the Function Switch is in IG1 or
IG2 position at startup, the Ion Gauge will start,
provided the Autostart criteria as described above are
met.
•If the Interlock gauge is not switched on (Pirani 1) or
not used (Active Gauge) then a warning message is
shown and emission cannot be started.
•If the Interlock gauge is Pirani 1, and Pirani 1 fails
open circuit, emission will be aborted if in progress, or
prevented from starting. This is considered a fault
condition, requiring the Function Switch to be
returned to OFF before another attempt can be made
to start emission.
External Inhibit mode

© Arun Microelectronics Ltd 2020. All rights reserved Page 17
Automatically start and stop IG1 or IG2 based on the state of the
external inhibit signal on the AUX connector (See section 12)
Only applicable to IG1 and IG2 Function Switch positions. In
BAKE or DEGAS Function Switch positions, the behaviour is as
Manual mode.
•An external inhibit gauge is chosen, either Pirani 1 or
Active Gauge. The pressure from this gauge will be
shown when the external inhibit signal is present.
•The external inhibit gauge pressure is only used for
the purpose described above.
External inhibit gauge pressure is not used as a
condition to start or stop emission.
•When the external inhibit signal is present, emission is
suspended, and the display alternates between
showing the external inhibit gauge pressure, and
external inhibit warning message.
•When the external inhibit signal is not present,
emission restarts.
•Functions at startup.
•Not reliant on the external inhibit gauge; if the chosen
external inhibit gauge is switched off (Pirani 1), not
used (Active Gauge) or open circuit (Pirani 1) then
only the external inhibit warning message is displayed
during external inhibit.
Gauges
Select the filament in use for each Ion Gauge.
Change of the filament in use is allowed without entering the
password if set.
Define the filament material type for each gauge. This
automatically sets the current limits for the filaments.
Use the Iridium setting for Thoria or Yttria-coated Iridium
filaments.

© Arun Microelectronics Ltd 2020. All rights reserved Page 18
Set the Ion Gauge overpressure trips (OVP) to suit the filament
material and your customary practice. The OVP will
automatically restrict the maximum trip pressure of any relay
assigned to that gauge to half the OVP.
A maximum OVP of 1E-3 mB/Torr is recommended for an
AIG17G with Tungsten filaments or 1E-2 mB/Torr with coated
filaments.
Define whether you require the instrument to change emission
current automatically. If set to ‘No’ the instrument will suggest
when a manual change in emission current is appropriate.
Refer to section 8.2 for Ion Gauge emission details.
Define whether you wish to add ion current to the Gauges
Display Sequence. Ion current in Amps will be displayed
following numeric Ion Gauge pressure.
Pirani Gauges can be switched on or off. Switching off
suspends the operation of Interlock and Autostart functions
when Pirani 1 is selected as the Interlock or Autostart gauge.
Define whether you have an Active Gauge connected. Selecting
‘No’suspends the operation of Interlock and Autostart
functions when Active Gauge is selected as the Interlock or
Autostart gauge.
Then, choose the analogue input format of the Active Gauge.
The options are:
•Linear, in which 0 to 10 V is mapped to a range of 0
to a selectable full-scale pressure value.
Specify the full-scale units, either mB or Torr, and the
full-scale value, either 1, 10, 100 or 1000.
•Log, in which 0 to 10 V is mapped to pressure
according to:
  
Where is the pressure in mB, and is the voltage.
Use this mode for the AML APG-1 Pirani Gauge.

© Arun Microelectronics Ltd 2020. All rights reserved Page 19
Select ‘Yes’to change the default gauge labels.
Each gauge can have a user-defined, three-character gauge
label. Select each gauge in turn and change each character
with 󰵎or 󰵍and confirm with ENT.
Relay assignment
You can assign any relay to any gauge or to ‘None’. Relays
assigned to ‘None’ are permanently de-energised.
Trip levels are set to maximum on assignment.
Trip levels for relays are set using the TRIPS push-button and
can be modified when the Function Switch is at position IG1,
OFF or IG2. Refer to section 7.2 for instructions on trip settings.
Relay D can also be assigned to Bake.
Bake
Set the bake temperature setpoint (50 to 250°C), total bake
time (1 Hr to 90 Hrs) and overpressure setpoint as required.
During Bake, relay D is energised when both the temperature
and pressure are below their setpoints. The hysteresis on
temperature is 5°C and on pressure is 50%. Refer to section 10
for more information.

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Degas
The settings for degas parameters should not be changed until
manual degas has been run (see section 9) and settings
appropriate for your chamber and usage have been derived.
Quick Degas.
Set the maximum power used in quick degas.
Programmed Degas.
Set the maximum power used in programmed degas, the rate
of power increase and the dwell time once maximum power is
reached.