Rudi's major achievements

Neutron physics
Radiation and metrology
Mass-spectrometric gas analysis
Vacuum and surface technology
International relations and congress organization

Mass-spectrometric gas analysis


Novel analytical methods

Comprehensive schemes for residual gas analysis that can be applied for quadrupoles as well as for all other types of mass-spectrometric gas analyzers - thus allowing to cope with the various types of cracking patters and their variation due to instrumental and vacuum conditions.

SGAP - Seibersdorf Gas Analysis Program

Introduction of the SGAP method in 1967 (see, e.g. Vakuumtechnik 20 (1971) 231): complete decomposition of RGA (residual gas analyser) mass spectra by a multi-stage matrix inversion scheme including consideration of the errors (standard deviations) of the measured RGA peak heights as well as of the instruments' calibration coefficients (in particular, the variations of the cracking patterns of the gases under consideration). Over a period of 30 years, the outgassing products of about thousand specimens - means several ten thousand mass spectra - have been analyzed within the frame of industrial contracts. After the first years, when only punching cards were available for data handling, a PDP-based data system was configured, allowing fully automatic gas analysis with just 4 keys needed to be pressed during the course of a complete analysis - with some times several hundred mass spectra to be evaluated for a single specimen measurement. Some relevant instrumentation can be seen in Rudi's photo archive on page Rudi's private lab 1997 - 2011.

VMS - Vector Mass Spectrometry

Invention of the VMS method. This method, based on multiple measurements of mass spectra with altered instrumental settings, allows the decomposition of inherently underdetermined mass spectra, i.e., if the number of gases in the system exceeds the number of evaluable peaks in the mass spectrum. By this means, even complex hydrogen-helium isotope mixtures can be analysed by conventional low-resolution residual gas analysers.

During the course of project T2.3/T277 of Association EURATOM-OeAW, a VMS system has been installed at ASDEX Upgrade (MPI Garching) and was operated over a period of two years under remote control from Vienna University of Technology. The VMS-method has been applied also for the analysis of H2-HD-HT-D2-DT-T2-3He mixtures released from metal-tritide samples.

VMS-C - Chemical-assisted VMS

For improved He-sensitivity with respect to hydrogen, the VMS-C method has been introduced and thoroughly tested. It is based on a defined reduction of the hydrogen partial pressure at the RGA by placing this instrument within a chemically pumped zone of the system, thus enlarging the helium-hydrogen-ratio at the RGA by a known factor. In our case, this has been achieved by mounting the RGA within a small orifice-controlled ZrAl-getter-pumped chamber. Potential applications are hydrogen-helium isotope analysis in nuclear fusion research, in particular, measurement of small He-concentrations in a deuterium background as well as more exact decomposition of mass spectra containing all possible combinations of hydrogen and helium isotopes.

CPC - Crack-Product-Calibration

Calibration of a gas-analysis system for a high-molecular substance with its main peak far off the mass range of the residual gas analyser. This is achieved by restricting the measurement to one or more selected crack-products of low mass numbers and relating their signals to one or two properly chosen noble gases whose signals are measured at the same time by the RGA and a BA-gauge with the later one serving as transfer standard. The method has been used e.g. for the measurement of silicone oil vapors with molecular weight of 105 g/mol, i.e., more than two orders of magnitude beyond the RGA's mass range.

System calibration by defined gas bursts

Calibration of total- and partial-pressure gauges by expansion of gas quantities defined by capacity-diaphragm-gauge readings inside a small calibrated volume, see e.g. Vacuum 41, 7-9 (1990) 2109. The gas-burst method has the advantage of a true in-situ calibration. It can be used for total and partial-pressure gauges, even during the course of a measurement. Pure gases (or mixtures of up to three gases) can be used.

In addition, novel methods for calibration of water vapor have been investigated.

Gases in materials:
Gas content, permeation, and outgassing

Investigation of gas contents of technical materials (metals, glasses, ceramics, optical fibres, polymers), as well as of mineralogical samples. Special interest was in Be and graphite (first-wall candidate for nuclear fusion devices), structural components of high-temperature solar collectors for solar energy power stations, refractory metals for high-temperature applications, and thermal superisolation layers for terrestrial and space applications.

Method: Outgassing in ultra-high vacuum with simultaneous RGA and BA-gauge measurements, data analysis by SGAP method. Numerous industrial contracts since 1970. More than 10.000 mass spectra evaluated with errors (standard deviations) between 1 and 3 % achieved. Coworkers: A. Breth, W. Grum, U. Langer, J. Neuwirth, W. Pointner, G.W. Schwarzinger, and G. Tirler.

Rudi's other major achievements
Neutron physics
Radiation and metrology
Vacuum and surface technology
International relations and congress organization

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