Paul Mc Donald (1947-2020)
I am sad to report that Paul Mc Donald died of cancer, aged 73, on Saturday 1 st August 2020, at his home in Ramsey, Hants.
As Director of the Cryogenic Industrial Advisory Unit, Institute of Cryogenics, University of Southampton, he was an incredibly popular teacher of post-graduates, and simultaneously a wide ranging research engineer of cryogenics, able to provide reliable answers to many low temperature problems.
During his 50 years working period, 1970 to 2020, Paul made many major contributions to Cryogenics and Cryogenic Engineering.
These contributions have revolutionised cryogenics from 10 cm diameter laboratory cryostats of 1970 to the monster 30 to 50 metre diameter storage tanks and the shipping of bulk cryogenic liquids in 2020 for industry, medicine and Space.
Following his Masters' degree in Cryogenics from the University of Lancaster, Paul joined Oxford Instruments in 1970, designing and installing low temperature cryogenic equipment around the world. By 1980, he was in the team that designed and built the first 500 MHz NMR superconducting magnet system. This provided an immediate contribution towards the first prototype MRI system, cooled by liquid helium, and requiring a refill of liquid every 100 days. For this invention and its medical importance, Oxford Instruments gained a Queen's Award for Technological Achievement, which Paul and two colleagues received from the Queen at a Palace reception. At the same time, Paul was working on the development of the first Continuous Flow Cryostat, which relied on his invention of a sintered copper heat exchanger and consequently avoided the100 day refill problem experienced in a hospital environment.
Cryocoolers with 'dry' helium cooling were not available until much later.
In 1979, the University of Southampton decided to set up the Institute of Cryogenics as a separate teaching and research department. Almost immediately, the Institute was overwhelmed by the industrial problems being met and required many research projects to be set up. At the same time a variety of teaching and training courses were being requested.
In 1982, Paul was recruited from Oxford Instruments and appointed Research Director of the Cryogenic Industrial Advisory Unit within the Institute.
The first success of Paul soon after his arrival was the recognition of the reliable and rugged performance of calibrated silicon diode thermometers, over the whole range of cryogenic temperatures from ambient at 273K to liquid helium at 1 K. A local Southampton firm was then persuaded to build silicon diode thermometers in a capsule for general use in cryogenics. The associated simple and reliable temperature measurements led to the sale of many such thermometers around the world, including NASA space rockets up to the present day. Their accuracy also led to a great deal of cryogenic fluid dynamics findings on low temperature fluids and their extraordinary high heat transfer properties down to 1 K.
Paul's success with accurate thermometers led to the 1990 development of cold electronics for data collection and digital functions for all sorts of instruments operating directly at working temperatures down to liquid helium.
Progress with cold electronics required testing the operation of all manufactured electronic systems when dunked in liquid nitrogen and liquid helium baths. Only 5% were found to keep working and these were selected to enable the development of cold electronics to move forward. The findings were published in 1992 during a conference in Houston, Texas, USA, when the main application was for instruments on the very large model aircraft in the very large cryogenic wind tunnels at Southampton University Aeronautics Department, NASA Langley, Virginia, USA, and Cologne, Germany.
These findings on cold electronics are now providing the grounds work for Quantum Computing at liquid helium temperatures in 2021.
Successful development of cryogenic concrete and frost-proof concrete as building materials was a straightforward finding, with collaboration from other departments at Southampton University.
Conventional concrete contains a surplus of free water after the concrete paste has hardened to a high strength structural solid. Subsequent removal of this surplus water by vacuum pumping, enables the structural solid to avoid crumbling, below the ice point at 273 K: the frost proof concrete is now also much stronger.
Following his many contributions to cryogenic technology, Paul's multiple areas of research have included the study of different foam materials at temperature ranges from 273 K down to Liquid Nitrogen at 77 and LNG at 120K.
Computer controlled production of thermal conductivity and insulation data enabled rapid testing of many possible insulation materials, in particular to reduce the expensive boil-off of LNG gas from stationary storage and shipping tanks.
Paul's unique up-to-date data on foams will also be valuable in the global distribution of Coronavirus 19 vaccines when/if they require freezing down to 193 K in thousands of low loss containers.
Paul's low conductivity insulations data will also be used for the next generation of space rockets using LNG as rocket fuel, in place of liquid hydrogen, enabling much larger rocket loads flying into space, to the Moon and Mars and beyond, as soon as 2030.
In conclusion, this obituary shows just some of the contributions Paul has made to cryogenic technology over 50 years of research engineering, all of which are being used today, and will be carried into world-wide future applications.
He will be greatly missed by all research and teaching staff together with the hundreds of former students of the Institute of Cryogenics, and will be remembered in countless ways by cryogenic engineers around the world.
His contribution to the revolution in cryogenics will never be forgotten.
Emeritus Professor of Cryogenic Engineering,
University of Southampton