ANGLO SCIENTIFIC INSTRUMENTS

Residual Gas Analalizörleri - Vakum Sistemleri

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AX80 RGA

The AX-80 mass spectrometer system can be configured to meet most Residual gas analysis and process monitoring applications. With mass ranges of 80amu and a choice of detector systems the AX-80 may be supplied as an "add on" to an existing vacuum system or as a complete stand alone unit with integrated vacuum and inlet system. The AX-80 uses a PC Computer as its system controller and its operating software is written in a high level language. This simplifies updating, and allows easy customising to meet specific process requirements. The user-friendly software operating under 'Windows' make the AX-80 easy to use in all RGA and gas analysis applications.

Key Benefits

	Low Cost
	Small Size
	Simple to use
	Comprehensive Software.

Complete RGA.

The Analyser.> The quadrupole analyser is available with a choice of ion sources, mass filters and detection systems. The standard ion source is a radially symmetrical design fitted with twin filaments and suits most applications. The standard filaments are tungsten but thoria coated iridium are available if required.
This compact unit contains the complete quadrupole electronics and plugs directly onto the analyser. Communication with the PC Computer is via the RS232. The unit has a performance and features only found on more expensive RGA's, and yet its small size and low cost is achieved by the use of the very latest electronic techniques.
Software features The new 'Windows' RGA software for the AX-80 mass spectrometer has been designed to be 'user friendly' and very simple to learn and use. For detailed information refer to the separate software leaflet.

Technical Data.
Mass Range	1-80
Resolution	10% valley between equal peaks.
Minimum detectable partial pressure	1x10^-10mBar Faraday,
Minimum detectable total pressure	5 x 10^-11 mBar.
Maximum operating pressure	1x10^-2mBar Faraday,
Electron energy	80eV
Ion Energy	6eV
Emission	100 uA *
Bake-out temperature	250C recommended. 350C maximum
R.F frequency	1.84Mhz std.(options 1.6Mhz - 4.9Mhz)
R.F. amplitude	800V p/p at maximum mass
Rod diameter	3.0 m.m.
Rod length	20 m.m.
Power requirements	17-26VDC 15Watt
Software specification	Refer to separate Software Leaflet.
P.C .Computer required.	Pentium preferred.

Order Information. - AX-80.
Complete Instruments	AX-80/80F	80amu RGA with Faraday Detector
Spare Analyzer Heads	AH80F	80amu Analyzer with Faraday Detector
Spare Filaments	SM100FT	Pack of 2 Thoria coated Iridium

Dimensions

Electronics unit 6 x 3 x 3.5 inches (152 x 76 x 88mm)

AX200 RGA

The AX-200 mass spectrometer system can be configured to meet most gas analysis and process monitoring applications. With mass ranges up to 200amu and a choice of detector systems the AX-200 may be supplied as an "add on" to an existing vacuum system or as a complete stand alone unit with integrated vacuum and inlet system. The AX-200 uses a PC Computer as its system controller and its operating software is written in a high level language. This simplifies updating, and allows easy customising to meet specific process requirements. The user-friendly software operating under 'Windows' make the AX-200 easy to use in all RGA and gas analysis applications.

Key Benefits

	Low Cost
	Very Small and light weight.
	Very Low power requirements.
	Simple to use
	Comprehensive Software.

Complete RGA.

The Analyser.> The quadrupole analyser is available with a choice of ion sources, mass filters and detection systems. The standard ion source is a radially symmetrical design fitted with twin filaments and suits most applications. The standard filaments are tungsten but thoria coated iridium are available if required.
This compact unit contains the complete quadrupole electronics and plugs directly onto the analyser. Communication with the PC Computer is via the RS232. The unit has a performance and features only found on more expensive RGA's, and yet its small size and low cost is achieved by the use of the very latest electronic techniques.
Software features The new 'Windows' RGA software for the AX-200 mass spectrometer has been designed to be 'user friendly' and very simple to learn and use. For detailed information refer to the separate software leaflet.

Technical Data.
Mass Range	1-100 or 1-200 std. (Lower mass options available)
Resolution	10% valley between equal peaks.
Minimum detectable partial pressure	2x10^-11mBar Faraday, 5x10^-14mBar SEM
Minimum detectable total pressure	1 x 10^-11 mBar.
Maximum operating pressure	1x10^-4mBar Faraday, 1x10^-5mBar SEM
Electron energy	70eV
Ion Energy	6eV
Emission	1 mA *
Bake-out temperature	250C recommended. 350C maximum
R.F frequency	1.84Mhz std.(options 1.6Mhz - 4.9Mhz)
R.F. amplitude	800V p/p at maximum mass
Rod diameter	6.35 m.m.
Rod length	100 m.m. std.
Power requirements	17-26VDC 15Watt
Software specification	Refer to separate Software Leaflet.
P.C .Computer required.	486/66 minimum. Pentium preferred.

Order Information. - AX-200.
Complete Instruments	AX-200/100F	100amu RGA with Faraday Detector
	AX-200/100M	100amu RGA with Dual Detector
	AX-200M	200amu RGA with Dual Detector
Spare Analyzer Heads	AH200F	100/200 Analyzer with Faraday Detector
	AH200M	100/200 Analyzer with dual detector
Spare Filaments	AX100FW	Pack of 4 tungsten
	SM100FT	Pack of 2 Thoria coated Iridium

Dimensions

Electronics unit 6 x 3 x 3.5 inches (152 x 76 x 88mm)

AX600 RGA

The AX-600 Residual Gas Analyser

The AX-600 mass spectrometer system can be configured to meet most gas analysis and process monitoring applications. With mass ranges up to 300amu and a choice of detector systems the AX-600 may be supplied as an "add on" to an existing vacuum system or as a complete stand alone unit with integrated vacuum and inlet system. The AX-600 uses a PC Computer as its system controller and its operating software is written in a high level language. This simplifies updating, and allows easy customising to meet specific process requirements. The user-friendly software operating under 'Windows' make the AX-600 easy to use in all RGA and gas analysis applications.

Key Benefits

	Additional facilities.
	Very Compact and lightweight RGA
	Low power requirement.
	Comprehensive Software.
	Twin Filament.

The Analyser. >
The quadrupole analyser is available with a choice of ion sources, mass filters and detection systems. The standard ion source is a radially symmetrical design fitted with twin filaments and suits most applications. The standard filaments are tungsten but thoria coated iridium are available if required. The standard mass filter is fitted with 6.35mm diameter cylindrical rods. The detector is a combined Faraday cup and Channeltron detector. A Faraday detector only is available if required for the lower mass range units.
This compact unit contains the complete quadrupole electronics and plugs directly onto the analyser. Communication with the PC Computer is via the RS232. The unit has a performance and features only found on more expensive RGA’s, and yet its small size and low cost is achieved by the use of the very latest electronic techniques.

Technical Data.
Mass Range Options	1-100, 1-200, 1-300 (Others available)
Resolution	10% valley between equal peaks.
Minimum detectable partial pressure	2x10^-11mBar Faraday, 5x10^-14mBar SEM
Minimum detectable total pressure	1 x 10^-11 mBar.
Maximum operating pressure	1x10^-4mBar Faraday, 1x10^-5mBar SEM
Electron energy	10 - 120eV
Ion Energy	1-20eV
Emission	20uA - 2 mA *
Bake-out temperature	250C recommended. 350C maximum
R.F frequency	1.84Mhz std.(options 1.6Mhz - 4.9Mhz)
R.F. amplitude	1200V p/p at maximum mass
Rod diameter	6.35 m.m.
Rod length	100 m.m. std. (125 mm above 200amu.)
Power requirements	17-26VDC 15-25 Watt
Software specification	Refer to separate Software Leaflet.
P.C .Computer required.	Pentium preferred.
Ion Source Options.	Open, Axial Beam, Cross Beam.
Baud Rate	600 to 56,600

Order Information. - AX-600.
Complete Instruments	AX-600/100F	100amu RGA with Faraday Detector
	AX-600/100M	100amu RGA with Dual Detector
	AX-600/200M	200amu RGA with Dual Detector
	AX-600/300M	300amu RGA with Dual Detector
Spare Analyzer Heads	AH200F	100/200amu Analyzer with Faraday Detector
	AH200M	100/200amu Analyzer with dual detector
	AH300M	300amu Analyzer with dual detector
Spare Filaments	AX100FW	Pack of 4 tungsten
	SM100FT	Pack of 2 Thoria coated Iridium

AX800 RGA

The AX800 Residual Gas Analyser.

The AX800 Series of computer integrated mass spectrometer systems can be configured to meet most gas analysis and process monitoring applications. With mass ranges up to 600 amu and a choice of detection systems the AX800 may be supplied as an "add-on" to an existing vacuum system or as a complete stand alone unit with integrated vacuum and inlet systems. The AX800 uses a PC computer as its system controller and its software is written in a high level language to simplify updating and to make it easier for customizing to meet specific process requirements. Color display and the flexibility offered by keyboard and mouse control of menu selection make the AX800 easy to use in all RGA and gas analysis application

Key Benefits

	High Precision
	Wide choice of Mass ranges
	Fast Scanning.
	Easy maintenance.

The AX800 Standard Analyser
	The quadrupole analyser is available with a choice of ion sources, Mass filters and detection systems. The Ion Source. The standard ion source is a radial symmetrical design with twin filaments. The semi-open construction makes it suitable for most applications. Thoria coated filaments to minimize out gassing are available as an option. The Mass Filter. The standard mass filter is a 125mm long single filter with 6mm diameter cylindrical rods. A Triple filter version is available (See Modular Analyser below) The Detector. Choices of either Faraday only or dual Faraday/multiplier detectors are available. The Mounting Flange. Normally CF63 or ISO63 flange is fitted. The quadrupole assembly can be mounted on larger flanges if required.
The AX800 Modular Analyser (Option)
Analysis of low volatile samples and condensable vapours may result in contamination of the analyser. This Analyser had been developed for quick removal and replacement of both the ion source and mass filter greatly simplifying cleaning and maintenance. If a spare ion source and mass filter are available then this simple procedure greatly reduces down time of the quadrupole system.	The Ion Source. The Ion Source simply plugs into the top of the mass filter housing without the need to make electrical connections and therefore can be quickly changed. The standard ion source is a radial symmetrical design with twin filaments. The Ion Source illustrated above is fitted with an axial gas inlet probe, twin filaments, source heater and temperature sensor. A radial aperture is provided for molecular beams, or use of solids probe. The semi-open construction makes it suitable for most applications. Thoria coated filaments to minimize out gassing are available as an option. Refer to the options page for additional Ion sources that are available.	The Mass Filter. The mass filter plugs in to the housing without the need to make electrical connections and therefore can also be quickly changed. This is particularly useful for the triple filter version . The standard mass filter is a 150 mm long single filter with 6mm diameter cylindrical rods. A Triple filter version is available. The Detector. Choices of either Faraday only or dual Faraday/multiplier detectors are available. The electron multiplier can be either Channeltron or discreet dynode type for continuous high output current monitoring. The Mounting Flange. Normally CF63 or ISO63 flange is fitted. The quadrupole assembly can be mounted on larger flanges if required.
	The RF Head This compact unit contains the pre-amplifier and RF generation/control circuitry and plugs directly onto the analyzer to prevent signal degradation. Choices of operating frequencies are available to give the best possible performance over the required mass range. The standard cable length is 2 metres but longer cables can be supplied if required.
The Control Unit. The Control unit contains all the main power supplies for the instrument including the emission and filament control circuits and the Computer Interface Card that are housed in a 2U high 19inch rack module.

Technical Data.
Mass Range	1-50,1-100,1-200,2-300. (Other option available)
Resolution	<10% valley between equal peaks.
Minimum detectable partial pressure	2x10^-11mBar Faraday, 1x10^-14mBar SEM
Minimum detectable total pressure	1 x 10-11 mBar. (If Fitted)
Maximum operating pressure	1x10^-4mBar Faraday, 1x10^-5mBar SEM
Electron energy	10-100eV
Ion Energy	2-20eV
Emission	100uA to 2mA *
Bake-out temperature	250C recommended. 350C maximum
R.F frequency	2.4 Mhz std. (options 1.2Mhz - 4.9Mhz)
R.F. amplitude	1350V p/p at maximum mass
Rod diameter	6.0 m.m.
Rod length	125 m.m. std. (175 m.m. for Triple filter)
Power requirements	105/115/220/240 volts 50/60Hz 80Watt
Software specification	Refer to separate Software Leaflet.
P.C .Computer required.	Pentium preferred.

Order Information. - Standard AX800.
Complete Instruments	AX800/100F	100amu RGA with Faraday Detector
	AX800/100M	100amu RGA with Dual Detector
	AX800/200M	200amu RGA with Dual Detector
	AX800/300M	300amu RGA with Dual Detector
Spare Analyzer Heads	AX800/200F	100/200 Analyzer with Faraday Detector
	AX800/200M	100/200 Analyzer with dual detector
	AX800/300M	Analyzer with dual detector for 300amu.
Spare Filaments	AX800/FW	Pack of 4 tungsten
	AX800/FT	Pack of 2 Thoria coated Iridium

SOFTWARE

Quadrupole Operating Software.

The new 'Windows' software for the Larimax mass spectrometers has been designed to be 'user friendly' quick to operate and very simple to learn and use.
Main Display Modes Bar-Graph Mode In Bar graph mode a region of the mass spectrum is measured at integral values of mass number and the resulting partial pressures are plotted against mass number in a bar-graph format. The first mass and scan width of the display can be quickley changed by the adjustment of scroll bars and the instrument gain range can be quickly changed from the gain display panel
DATE/TIME is updated at the start of each scan, and stored if a spectra save is implemented.		TOTAL ON/OFF Select ON and Total Pressure will be read and updated at the end of each scan
PRESSURE SCALE Choice of mBar/Torr/Pascal
GAIN PANEL UP/DOWN buttons increment the gain AUTO button selects auto gain		FIRST MASS & SCAN WIDTH Scroll bars. A simple and quick way to set the start and finish masses of the scan

Split Screen Library Search Mode In Split screen mode the graphics area is divided into 2 parts. The lower part contains the normal online spectra. The Upper part displays the library spectra and search panel. The library contains common residuals and semiconductor gases.
	Search Panel. Allows user input of search mass and search type with display of search results and compound names. Buttons enable scanning of found spectra.
	Stored Library Spectra displayed on upper half of screen
	Normal online Bar Graph Spectra displayed on lower half of screen
	First Mass and Scan Width controls are common to both displays to maintain mass alignment

Channel Mode The Channel and Trend modes are identically operationally but differ in the way that recorded data is presented. In both cases the mass spectrometer makes measurements of partial pressure at up to 16 mass numbers using previously defined gain ranges and detectors.
Channel Table. One Column for each channel peak, and 5 rows for peak data. To change the data in either of the first 4 rows simply click on the data that you wish to change. The box will become highlighted and a control will appear on the Change Data panel above. Now adjust the control to change the data.		UP/Down buttons to change the number of channels being Scanned and displayed. Any number between 1 and 16 can be selected.
Information/Message Display box.		Mass number being read by mass spectrometer

Trend mode shows the same peak information as channel mode except the peak heights are plotted against time. Therefore all controls including the Channel Grid Table will remain the same in both modes.

Trend and Leak Detect		Analogue Display

This display option allows the partial pressures of upto 16 masses to be plotted against time. The plot interval can be selected and each mass is depicted as a different coloured line. The leak detect mode is a single channel version with the default mass 4 selected for helium.		This is mainly used for checking on the analyser condition. It allows the peak shape and resolution of the analyser to be monitored and also simplifies the checking of mass alignment.

AUTO-RUN.
If Auto-Run has been selected the display will change to a table format. Filaments will switch on automatically. There will be a short delay whilst the filaments out-gas total pressure will be measured and then the instrument will start scanning over the first 100 amu. At the end of a scan the software will select the 8 largest peaks in the spectrum and display these in order on the table. The mass, gas and percentage for each gas will be indicated. The software will continue to monitor these major peaks, and comments will appear giving vacuum diagnosis, conditions, vacuum problems and how the vacuum conditions are changing. This auto-Run facility is mainly for the system user, who uses the RGA as a diagnostic tool and problem solver. All by the pressing of a single button.
At the bottom of this display are 3 buttons. One which closes this operating mode and returns the user to the main display modes, the second allows the whole process to start again and the third button takes the user direct to leak detect mode.

TOP TOOL BAR. (Drop down Menus) Software control.

File menue
SAVE SETTINGS. Saves all the current user settings into a text file. These include first mass Scan width, gain, channel peak information, detector, etc.

LOAD SETTINGS. Loads all the last saved setting information. This is also automatically loaded during boot-up of the software, so the instruments returns to the same condition, and settings as it was when switched off.

SAVE USER SETTINGS. Saves all the current user settings into a Named text file. Any number can be saved. Useful for different operators, or different configurations of the Software.

LOAD USER SETTINGS. Loads all the last saved setting information from a Named user settings file.

SAVE SPECTRA. Saves the current spectra at the end of scan into a text file along with all instrument parameters and date /time information.

RETRIEVE SPECTRA. Retrieves spectra from file. The software reconstructs and displays the spectra and all instrument settings at the time the spectra was saved.

DATALOG. Saves Channel/Trend Spectra data for up to 16 peaks into a text file. This data can be printed, displayed or transferred to a spreadsheet for further processing.

PRINT. Prints hard copy of the current displayed spectra in graphical form.

EXIT. Automatic shut down of instrument and software.

Display Mode menue
Selects one of the 5 main operating modes. Bar Graph, Analogue, Channel, Trend and Leak Detect.

System menue.
Selection of set up menus for changing serial port settings and engineers panels for testing hardware and configuring the software to the hardware in use.

Options menue.
Allows leak mass to be changed, mass calibration, and High Pressure mode to be selected.

Scan menue.
Selects different fast scanning options, and single shot/normal scan mode.

Background Subtract.
Menu options to allow the background spectra to be stored and the later subtracted from the current spectra after gas has been admitted to the system.

Library Mode.
Allows Split Screen Mode to be selected with a search facility to display Library spectra above the current spectra. (Bar-Graph Mode only).

Help.
Provides online help with descriptions of the main software features and controls.

BOTTOM TOOL BAR Mass Spectrometer Control.

Status.
Displays current status of the filament and emission, and will display any warning messages should the filament fail.

Filament Control Panel.
Allows filaments to be selected ON/OFF with single button operation.

Detector Control Panel.
FARADAY button. Selects Faraday plate ion detector mode.

S.E.M. Button. Switches on the high voltage to the Secondary electron multiplier. (Dual detector instruments only).

CAL. Button. Automatically calibrates the electron multiplier to a pre-set gain. A Calibration panel indicates progress and gain achieved at completion.

Scan Control Panel.
START button. Starts the instrument mass scan. Either from the first mass, first channel, or last stop position.
STOP button. Stops the current scan in its present mass/channel position.
RESET button. Resets the mass scan to first mass or channel 1, in either start or stop mode.

Precision Code.
UP/DOWN buttons. Gives selection of 8 precision codes. Higher code number increases the number of peak readings, integrations, and therefore gives more accurate and reproducible results.

Peak Width.
Up/Down buttons. Changes the amount of the peak that is scanned. 0% represents a single plotting point. 100% corresponds to 16 plotting points.

OPTIONS

Ion Source Options.

Open Ion Source. (Fitted as Standard) This ion source is used for residual gas analysis and simple gas analysis applications.	>
	<	Axial Beam Ion Source. This ion source is specifically for analysing either molecular beams or ion beams from an external source. The ion source has a low profile with side mounted filaments so that the source can be positioned close to the exit hole of a source of ions or molecular beam that is in line with the axis of the quadrupole.
Cross Beam Ion Source. This source is for molecular beams that enter the ion source at right angles to the quadrupole. A clear aperture of 3,5mm avoids contact with the molecular beam. This source is normally used in applications where condensable vapors may be present within the molecular beam that could contaminate the quadrupole filter.	>
	<	NIBTRON Ion Source. This source is specially for gas analysis only and has many unique advantages to the traditional gas tight Ion Source.

.Mass Filter Options.

Single Mass Filter. (Fitted as Standard) A Low cost single stage mass filter using cylindrical rods for low mass applications.

Saddle mounted Filter. A high precision saddle mounted mass filter is available as an option on our range of instruments. It is easily de-mounted for cleaning. This enclosed filter offers improved sensitivity, resolution and abundance sensitivity.

Dual & Triple filters. These are available based on saddle mounted mass filters, and are normally chosen for special applications or when the highest performance/resolution is required.. Available on the AX800 instrument only.

Detector Options.

Faraday Only. A Faraday plate detector for ion collection. Used mainly for higher pressure applications when greater ion currents are available for collection.

Dual Faraday/Channeltron. The Channeltron (SEM) provides a high level of amplification of the ion beam and therefore provides detection of much lower ion currents. When in SEM mode the pre-amplifier can be operated at a lower gain and faster scanning speeds are possible.

Discreet SEM. A discreet dynode Electron multiplier is available on the AX800 as an alternative to the Channeltron Electron Multiplier. This has much larger surface area of secondary electron electrodes and therefore offers much longer life when operating on continuous high signal levels over prolonged periods of time. The Faraday option is not available when this device is fitted.

Pulse Counting. Provides the ultimate in detection by counting individual ions arriving at the detector.. Normally used in trace gas analysis applications where the lowest level of detection is required. A special version of the electronics is available that includes a counting pre-amplifier, system clock, counter, and interface for transferring the accumulated ion count to the quadrupole software for display. (Special order)

High Temperature Operation

Thermal Extender. Allows operation of the quadrupole whilst the analyser is at high temperature This option is available on most of our RGA instruments and has to be fitted to the analyser at the time of manufacture. It extends the back of the analyser by approx 24 cms so the plug-on electronics is now separated from the analyser hot zone.

Filament Options

Technical Notes.

Which Filament?

The majority of our competitors use a twin filament assembly. That means that when one of the filaments blows the customer has a difficult decision. Does he replace the filament assembly throwing the remaining good filament away, or does he run on the second filament and hope it does not blow during a critical measurement when there is no back-up.

All ASI/Larimax RGA’s are fitted with two filaments. The filaments are individually replaceable. Therefore if one filament blows, that filament can be changed at a convenient time. And the other good filament remains on the analyser

Tungsten Filaments.	Advantages	Disadvantages
Operating temperature for Pure Tungsten approx 2200C	A good low cost general purpose filament.	Life is reduced in oxidising atmospheres above 5x 10e-6mBar
Operating temperature for Thoriated Tungsten (1% Thoria) approx 1950C	Under high vacuum, below 10e-6mBar filaments will last many months and sometimes many years.	Life is reduced in high partial pressures of water vapour (10e-5mBar) due to filament erosion.
	Can be used at high pressure in inert atmospheres.	Tungsten filaments usually produce background peaks at mass 28 (CO) and 44(CO2).
	Can be used in Hydrogen or reducing atmospheres.	Sudden exposure to high pressure above 10-2mBar of oxidising atmosphere can cause instant oxidation and burn out of filament.
	Safe to handle filaments.	Will burn out instantly if switched on at atmospheric pressure.
		Can produce a catalytic action with some chemicals.
Comments:- Slow evaporation of filament will cause the filament to become thinner over a very long period of time, with a reduction of operating current eventually leading to failure. Normally recommended in medium and high vacuum systems for general-purpose residual gas analysis.

Thoria Coated Iridium.	Advantages	Disadvantages
	Life typically 12 months or more.	More expensive than tungsten filaments.
Operating temperature approx 1400C.	Runs at lower temperature and therefore lower out gassing from Ion Source.	Poisonous and mildly Radio-Active. Disposable gloves and mask should be worn when handling filaments.
	Does not produce CO or CO2 and therefore these background peaks are much lower.	High levels of hydrogen can cause reduction of the oxide coating with an increase in water background, and a consequent reduction in filament life.
	Can be used at high pressures in oxidising atmospheres.	Severe Shock or vibration can dislodge the coating.
	Will tolerate high pressure burst.	Cannot be chemically cleaned.
Comments:- Normally recommended for gas analysis applications and for use at high operating pressures, especially if oxidising gases are present. Also may be preferred in UHV conditions when the lowest possible background is important.

Yttria Coated Iridium.	Advantages	Disadvantages
Operating temperature approx 1600C.	Similar to Thoria	Similar to Thoria (See Comment below)
Comments:- Sometimes chosen as an alternative to Thoria because it is not Radio-active Yttrium Oxide absorbs CO2 and NH3 ( if present) from the atmosphere. Long term exposure may convert the oxide to the carbonate. If this happens then it may outgas large amounts of CO2. when first operated, as the carbonate is converted back to the oxide. Yttria filaments should be stored & systems vented with dry nitrogen or an inert atmosphere if possible, if prolonged exposure to atmospheric pressure is required.

Filaments in other materials are available to special order.

NIBTRON Data Sheet

THE NIBTRON ION SOURCE. (SUPPRESSED BACKGROUND)

A major breakthrough in quadrupole mass spectrometry has been achieved by ASI with the introduction of the NIBTRON ion source. This Ion Source is available as an option, on the ASI quadrupole gas analysis systems and provides the following advantages and unique features:-

1) Elimination of 99.9% or more of the interfering background peaks.

2) Provides greatly improved accuracy and performance.

3) Allows much simpler, lower pumping speeds, and hence much lower cost vacuum systems.

4) Eliminates the need for bake-out ovens.

5) Allows much smaller gas samples to be measured.

6) Reduces memory effects from previous gas samples

7) Eliminates catalytic reactions from the hot filament being measured.

8) CO and CO2 from tungsten filament eliminated.

9) Sample gas measurement not affected by variations in pumping speed, or gas discrimination.

Portable Mass Spectrometer systems

Both the AX200 and AX600 mass spectrometers are small low power (16W/20W) mass spectrometers. When fitted with the NIBtron Ion Source they are ideal for portable battery powered gas analysis systems using small ion pumps. The gas load on the pump is 10 times lower than a conventional ion source to produce the same signal current. The sample gas can be can be further reduced because of the absence of background peaks. Therefore the total gas load on the pump can be reduced by a factor of 100 or more. This light gas load on Ion pumps greatly reduce problems of argon instability, the possibility of stalling the ion pump and reduces the power requirements of the pumping system.

CONVENTIONAL ION SOURCES. Ionise both the sample gas and the residual gases present in the vacuum system. These residual background peaks often make gas analysis very difficult. To reduce these background peaks to acceptable levels it is essential to frequently bake the vacuum system to high temperature. Even after bake out, residual peaks are still present, limiting the accuracy to which gas analysis can be achieved. These residual peaks will subsequently increase in amplitude when sample gas is introduced into the vacuum chamber due to desoption from the chamber walls, making it difficult to determine the percentage of sample peak that may be present in a changing background.

NIBTRON. The new NIBTRON quadrupole analyser has an extremely low sensitivity to residual gas ions, whilst at the same time has a high sensitivity to sample gas ions introduced via the inlet probe. This improvement in ionisation ratio is in excess of 2000, producing clean sample gas spectra even under poor vacuum/high background conditions.

This is illustrated below. The following two scans were made using a two small ASI RGA mass spectrometers. One fitted with a standard electron impact source and the second with a NIBTRON source. They were operated together on the same vacuum system under identical vacuum conditions and cover the mass range from approx. 32-50amu. The test were deliberately carried out on a oil contaminated vacuum chamber to produce a very high background of residual gases . The system pressure was at 3 x 10-6 mBar. A leak valve was then opened, admitting an air sample, increasing the pressure by 1 x 10-6mBar.

CONVENTIONAL SOURCE.

The background pressure is 3x10e-6 mBar and the air sample pressure is 1x10e-6 mBar. The very high level of background peaks make it difficult to measure the argon or CO2 peaks from an Air sample. The mass 40 peak is mainly background and the CO2 peak at mass 44 is completely masked by the high background of CO2 produced mainly from the filament.

NIBTRON ION SOURCE.

The same background conditions as above. The background pressure is 3 x 10e-6 mBar and the air sample pressure is 1x10e-6 mBar.

NOTE.- the complete absence of residual background peaks

Masses 32, = O2 approx 150 x FSD

Mases 33, 34=Atmosheric oxygen isotopes.

Mass 40= Atmosheric Argon. 10xFSD

Mass 44 Atmosheric CO₂. Approx 330ppm.

Note.- The higher sample peak heights are due to the high sensitivity of the NIBTRON Source.

NOTE 1:- Because of its very low sensitivity to residual background gases, the NIBTRON is totally unsuitable for fitting to existing vacuum systems for Residual Gas Analysis Applications. It will only analyse gases introduced via the NIBTRON gas inlet probe.

NOTE 2:- The NIBTRON ION SOURCE is unique to Anglo Scientific Instruments and should not be confused with a technique used by other manufactures whereby a background spectra is sampled and stored. Gas is introduced and then the stored background is subtracted from the sample + background spectra. This technique has limited use because the background spectra is frequently changing with time and the introduction of the sample gas will cause further changes in the background gases due to adsorbtion and /or desorbtion of gases from the chamber walls caused by pressure changes within the vacuum chamber. Because the background is now different to the stored background The result can give rise to large errors particularly on smaller peaks. Some peaks may be present that do not exist and others that should be present are not shown. The result of some peaks indicate a negative result..

The NIBTRON ion source is a vastly superior technique completely free of these errors

VACUUM SYSTEMS

Vacuum Systems and Complete Gas Analysis Systems.

The COMPASS concept is to provide complete solutions to gas analysis problems. With a wide choice of inlet systems, vacuum systems, ion sources and flexible software, Compass can be easily configured to your application.

Key Benefits

	Fully Enclosed
	Choice of pumping configurations
	Fully interlocked,

Mass Spectrometers by their very nature require a high vacuum environment to operate. This is provided by a High Vacuum System. Gas that requires analysis is then leaked into the high vacuum system at a controlled rate by the Inlet System. There is no such thing as a perfect vacuum. Residual Gases are always present. These residual gases may interfere with the gases that require measurement therefore it is important that these residual gases are kept to a minimum. The better the vacuum the lower the residual gases.

The Main High Vacuum System.

Most ASI mass spectrometers are small and therefore only require a small vacuum housing. The amount of gas required for analysis that will be leaked into the quadrupole Ion Source is also very small, therefore for the majority of gas analysis applications the main high vacuum pump can be satisfied by a small turbo-molecular pump. A small rotary vane pump will provide the low backing pressure for the turbo-pump.

Therefore a typical high vacuum system will normally contain the following items.

1. Fully enclosed Cabinet (Floor standing or Bench Top) with Fan cooling.

2. Mass Spectrometer housing with ports for inlet system and high vacuum gauge.

3. Turbo-molecular pump with splinter shield..

4. 2 Stage Rotary Vane Pump, with Fore-line trap and Oil Mist Filter. (Backing pump for turbo).

5. Anti-vibration mountings for the pumps.

6. Main switch panel and fuses.

The following additional items form a Complete Gas Analysis System.

7. 2 Stage Rotary Vane Pump, with Fore-line trap and Oil Mist Filter. (for inlet system).

8. Inlet system.

9. Fitting of High and low vacuum gauges. with power supply .

10. Mass Spectrometer, control electronics and power supply.

11. Additional wiring to provide interlocking between the pumps gauges and mass spectrometer for 'Fail Safe Operation'.

Compass vacuum systems are configured for each application.

INLET SYSTEMS

In order to interface the low pressure requirement of the mass spectrometer to the environment of the 'real-world' and hence cater for a wide range of analyses, Compass includes a choice of inlet systems from simple leak valves to computer controlled multi-stream gas samplers. Many inlet systems are specifically designed to meet particular requirements.

Further information on choice of inlet systems.

VACUUM SYSTEM

	Compass vacuum systems are configured for each application. The selection of turbo-molecular pump, Backing pump and control/monitoring equipment is made easier by relying on the wealth of experience of Larimax vacuum engineers. High and Low vacuum gauges are normally fitted as standard to provide system interlocking for Fail Safe operation.
	< Floor Standing System. Complete gas analysis system in fully enclosed mobile cabinet.		^ Compact Bench-Top System. Complete with High Vacuum system, Capillary inlet for atmospheric sampling, Quadrupole and electronics

INLET SYSTEMS

Quadrupole Mass Spectrometers, because of their nature, require an operating vacuum of 10-4 mBar or better. However most processes which need monitoring occur at a pressure in excess of 10-4 mBar. It is necessary therefore to have some form of interface between the mass spectrometer and the process vessel. These interfaces are called Inlet Systems and the type required is dependent upon the application.
Capillary Inlet This system is a form of continuous gas sampling, and may be used across a pressure range of 10-4 mBar to atmospheric pressure (1000 mBar). It consists of a narrow tube which connects the sampling point to the mass spectrometer vacuum system. The length and internal diameter of the tube have to be selected according to the pressure at which the sample is taken.
The disadvantage of this system is that at higher sampling pressures ( above 100 mBar) the response time becomes very long ( of the order of a few minutes ) due to the length of the tube. This can be overcome by a bypass type inlet system.
Capillary Inlet with bypass This type of inlet system is better suited to sampling over a pressure range from 100 mBar to atmospheric pressure. The operating principle is that a capillary tube is connected to a T-piece which is attached to a rotary pump. To the third arm is fitted a molecular flow leak or leak valve. Gas is drawn along the capillary by the rotary pump and a small portion of the gas which flows through the T-piece, passes across the leak and into the mass spectrometer.
This inlet requires a gas flow of approximately 20 ml min and achieves a response time of better than 100 ms. Capillary inlets are also available with a heater, which improves response time, and with an auxiliary pump to draw the sample through the bypass line. A crimp at the sample end to restrict the sample gas flow and a throttle valve on the bypass pump will allow much smaller sampling rates and maintain good responce times.
Leak Valve Inlets A good, continuous sampling, leak valve can provide the flexibility to sample across a range of 10-5 torr to well above atmospheric pressure. The operating principle is the precise control of a knife edge biting into a surface. The knife edge position is controlled by a fine screw operating mechanism with a calibrated dial so that a particular leak rate may be reproducibly set. The main disadvantage of this method of gas sampling is that fractionation of the gas occurs across the valve seat and the degree of fractionation depends on the leak rate setting. It therefore makes calibration of this inlet difficult. Response times when sampling from higher pressures may also be long unless attention is paid to producing a continuous gas flow across the valve seat. The inlet is available either as a general purpose, polymer sealed valve or as an all metal precision valve.
Membrane Inlets A membrane system consists of a tube terminating in a special semi-permeable membrane stretched over a grid. The application and the components of interest in the sample determine the type of membrane selected, as the membrane can exert considerable selectivity. Perhaps the most common types of membrane material employed are Teflon and silicone rubbers. Teflon is used where gases are to be monitored in the absence of solutes and where water is in high abundance.
Silicone is highly permeable to oxygen and can be used for the monitoring of organic compounds in situ. The major application of this inlet is in sample enrichment, particularly of organic materials, where the low levels would fall below the normal detection limit of the mass spectrometer. Enrichments by a factor of 200 are possible giving detection levels down to the low ppb.
Batch Inlet Continuous sampling techniques are satisfactory provided the mass spectrometer can be sited close to the sampling point. As this is not always possible a sample must be collected in a suitable vessel and transferred to the mass spectrometer. Introducing the gas into a vacuum system requires a batch inlet Batch inlets can be specially designed to meet particular applications but they generally consist of a reservoir that is connected by valves to a vacuum system.
The sample can be introduced through a septum port (if the sample is in a gas syringe) or through a valve port (if contained in a glass or metal collection flask). Options might include the ability to purge the reservoir with inert gas or heat the chamber to reduce background levels between samples (especially useful if water is being measured). Another useful option is the addition of a pressure gauge.
Dual inlets. Dual Inlets consist of a high conductance isolation valve, and a leak valve placed in parallel across a single inlet line. The wide range in the respective conductance's means that this single system can sample from atmospheric pressure to high vacuum. This capability is particularly useful in applications such as sputtering where the pressures can alter dramatically during different stages in the process.
MULTI_STREAM GAS SAMPLING. The instruments are not expensive but we still accept that most users would prefer to introduce multiple samples into one mass spectrometer rather than buy a mass analyser for each sample stream. The multi stream gas sampling inlet allows the connection of up to 32 gas streams to one capillary inlet. Which is then used to introduce each selected sample into the source of the analyser. All streams not being sampled flow through their own individual inlet and outlet connections. Both the operation of electrical switching to select the channel (which can be one or more calibration gases) and determination of dwell time per channel can be under computer control. This inlet is very versatile but a typical application is for the sampling of dissolved gases (see membrane inlet) and off gases from multi-vessel fermentation and cell culture installations.

Solids Probe.

Analysis of solids that can be attached to a small cup at the probe tip. A built in heater at the probe tip heats the sample to slowly evaporate the sample. The probe usually is inserted into the vacuum chamber via a vacuum lock. The higher temperature probes are normally water cooled. This probe is used in conjunction with a cross beam Ion Source.

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Bu sitenin son güncelleştirilme tarihi 26/02/10

Key Benefits

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Key Benefits

Key Benefits

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