IOP Groups
6th RGA Users Meeting
2 March 2005
This one day meeting of the Residual Gas Analyser (RGA) Users Group was held on Wednesday 2nd March 2005 at the Rutherford Appleton Laboratory, Oxfordshire.
Organised by:
The Institute of Physics (Vacuum Group)
CCLRC Daresbury Laboratory (ASTeC Vacuum Science Group)
CCLRC Rutherford Appleton Laboratory (ISIS Vacuum Group)
SS Scientific Limited
Organiser's Report (supplied by Steve Shannon)
The aim of these meetings is to bring together industrial, academic and research based RGA users with suppliers of RGA's in a workshop style meeting. There were no invited talks, but 10 contributed talks covering a wide range of applications of RGA's. The presentations were kept short to allow plenty of time for questions and general discussions during the breaks. At the conclusion of the meeting there was a tour of the ISIS facility or a chance to view construction (both the civil engineering and vacuum hardware) of the new Diamond Facility.
Thanks to the sponsors, the meeting was free of charge for the 72 delegates who helped to make this meeting the most successful so far. A photograph of attendees, full copies of presentations and other information about the RGA User Group can be found on the dedicated website: http://www.rgausers.org.
The meeting opened with a welcome and introductory talk from Dr John Thomason, Head of the ISIS Vacuum Group, Rutherford Appleton Laboratory. John introduced CCLRC and its sites, of which Rutherford Appleton Laboratory offers the large scale facilities of ISIS, Lasers and Diamond. The range of programmes at Rutherford: Particle Physics, Space Science, Technology Centres, Energy Research Unit, Micro and Nano Structures, and Radio Communications, were all touched upon before John concluded with a vision of ISIS now and into the future.
Hugo Shiers from the Diamond Light Source presented a talk about the RGA System for Diamond. Hugo revealed the uses and requirements for the RGA's that led to 146 instruments being purchased for the new facility, with MKS Spectra being the chosen manufacturer. The large distances between the partial pressure measurement and data presentation is leading to a sophisticated RGA network.
Guenter Peter, Pfeiffer Vacuum, gave an interesting overview of the RGA as a Quadrupole Mass Spectrometer in UHV Systems. After reviewing a range of applications of RGA's, Guenter reminded us of the basic physics requirements for UHV systems. He presented a range of 'facts' from an experienced vacuum technologist to help any newcomers avoid the pitfalls that are sometimes overlooked. The talk contained useful information about spectral interpretation, materials for use in UHV and baking with particular emphasis on the elimination of cold spots.
Reduced Manufacturing Cycle Times through improved Vacuum Integrity Testing was presented by Michael Gibbons from Applied Materials UK (Horsham). Mike demonstrated how Applied Materials have dramatically reduced the testing and validation times of new production systems, both in the factory and onsite during process tool commissioning. By using an RGA to monitor the nitrogen partial pressure, Applied Materials are able to prove if the systems leaks within 40 minutes, rather than several days that it takes to initially reach the ultimate base pressure of the system.
Dr Ron Reid from Daresbury Laboratory reviewed the Challenge of XHV. Ron showed us the increasing requirements for XHV conditions across a range of applications. The only solution is to reduce outgassing, and a 'recipe' for achieving XHV was presented that left only hydrogen, hydrogen and yet more hydrogen (relatively speaking!), so an RGA is not very interesting. Yet this conclusion leads a specification of an XHV RGA with a 'cold' ion source, low emission current and ion counting techniques.
Dr Steve Taylor, Liverpool University, brought the morning session to a close with a theoretical look at Simulation results for round and hyperbolic electrodes in Zone I and Zone III. A theoretical QMS (Quadrupole Mass Spectrometer) model has been developed at Liverpool University which has been applied to both round and hyperbolic electrodes as used in RGA's. The model has also explored the higher stability region (Zone III) in addition to the traditionally used Zone I mode of operation of RGA's. As might be expected, hyperbolic electrodes are preferred for quantitative measurements, but employing higher stability regions also offer the possibility of univariate calibration. Steve demonstrated the quantitative benefits of the higher stability region with the potential to separate out very close spectral peaks down to 0.01 amu.
Ian Koch, Thermo Electron Process Instruments Division, presented Taking Care of your RGA. We were treated with a comprehensive insight into the Do's and Don'ts of owning an RGA from an 'insiders' viewpoint.
Shaun Hughes, Head of the ISIS Vacuum Group, presented an Overview of the ISIS Accelerator and RGA Systems. Shaun informed us of the sheer scale of the ISIS high vacuum facility built to UHV standards. A number of special requirements, not least the high radiation levels, were reviewed to show how ISIS presented a range of challenges different to the norm and how RGA's were employed to overcome some of these problems.
Holger Norenburg, Technolux Limited, introduced a new application of RGA to most members of the audience: Permeation Studies with a RGA Mass Spectrometer. Holger described a number of practical examples of permeation and explained why it was important to quantify permeation rates. The mass spectrometer (RGA) method was illustrated and results presented. With a sensitive detector and careful elimination of background contribution to the measurements, both qualitative and quantitative results have been obtained.
Robert Pearce (Euratom/UKAEA) ended the day winning the award for the longest title: The Practical Application of the Quadrupole RGA in Determining the Outgassing of Materials for use in UHV Applications and in Analysing Gas Species Stored on Cryogenic Pumps. Robert's talk kept the audience awake with stories from the world of vacuum and surface cleanliness for UHV systems. We learned about the outgassing characteristics of wallpaper paste; the means to a perfect XHV system by baking the cables thus minimising the RGA signal; the ITER fault simulator available from Curry's; and the small differences between the ideal system for baking and measuring outgassing and the system employed at JET. There was lots of serious science included, outstandingly the referencing of RGA data to the cryogenic panel temperature and known vapour pressure data.
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