The Annual Symposium of the American Vacuum Society is the world’s main yearly vacuum conference held in Columbus, Ohio from the 20th to 25th October 2019.
There were 27 parallel sessions in a wide range of topics and over 2500 registrants.
The summary of the program and the abstracts of the papers presented can be found in these attached documents.
Materials and Outgassing
There were several papers discussing materials and outgassing. Martin Wuest of Inficon presented the results of the Atomic Layer Deposition of Al2O3 of all components of calibration vacuum chamber made from 304L stainless steel. ALD was chosen for its superior uniformity compared with PVD and plasma spray. This coating reduced outgassing rates by a factor of 40 to a value of 4e-13 mbar.l/s/cm2. James Frederick of the National Institute of Science and technology (NIST) presented work on the measurement of H2 and water outgassing rates of 7 identical 3 litre chambers with different common vacuum materials and treatments. The outgassing rates were measured by the rate of rise method.
Some of the major results showed that Ti may actually getter hydrogen and that vacuum firing 316L stainless steel reduces its outgassing by a factor of 150. A conclusion was for XHV Al, Ti , vacuum fired 316L and 316L-LN ESR, and A36 mild steel were suitable materials. Maxwell Martin of the Jet Propulsion Laboratory presented the means to use quartz crystal microbalances to conduct in-situ monitoring of next-generation space exploration hardware.
Pressure measurements and calibration
NIST also presented work (Kevin Douglas) on the progress towards pressure measurements based on refractive index. A ‘dual-wavelength’ approach is being developed to provide primary traceability for the NIST Fixed Length Optical Cavity method. They also presented a paper (Jay Hendricks) describing the next generation of SI traceability of the Pascal. This will give an energy density definition using photonics based device exploiting ‘both of the properties of light interacting with a gas and that the pressure dependent refractive index of helium can be precisely predicted from fundamental first-principles quantum chemistry calculations’.
On the theme of calibration M-V Johansson of Aix Marseille University presented the application of micro-sintered stainless-steel membranes. They were found to constant conductance for low pressure and in combination with Capacitance manometers they can be used in combination with turbomolecular pumps to provide in-situ gauge calibration.
Several reports were made on the use of Non Evaporable Getters (pumps and coatings) including at the CHESS facility, Argonne National Laboratory, LCLS II (SLAC) and APS-U. Yevgeniy Lushtak of CHESS-U reported on the synchrotron radiation induced vacuum conditioning status and ’the computational model developed to accurately simulate the vacuum conditions whilst taking into account the NEG saturationand radiation-induced chamber cleaning’. Derek Hammar of Coe College presented a poster on the modelling of NEG pump operation during saturation.
Junichiro Kamiya of the Japan Atomic Energy Agency described work, in collaboration with Osaka Vacuum and Tokyo Electronics Company Limited, on the development of an Osaka turbomolecular pump with Ti alloy (6% Al, 4% V). This has much higher mechanical strength than aluminium alloys and allows a higher rotational speed of the rotors. A 30% increase was shown to increase the pumping speed by a factor of x 1.3 and compression ratio by x 12.5 (with theoretical improvements of x 1.8 and x 17 respectively).
Highlights of the poster sessions included the work of JEOL and KEK (Japan) on the application of NEG coatings to allow the transportation of UHV (electron microscope) systems without electricity.
The associated exhibition has more than 110 exhibitors, a highlight being the new nXRi multi-roots pump on the Edwards Vacuum stall.
The AVS continues to attract high quality novel contributions. The pumping presentations were very interesting with direct application to real-life situations. More sessions would be ideal perhaps regarding vacuum fundamentals and gas-surface interactions. Not all major vacuum manufacturers were present at the exhibition.
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