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Scientists of Wales: Frank Llewellyn-Jones

(December 03, 2014)

Cymraeg

Frank Llewellyn-Jones (1907-1997)

Frank Llewellyn-Jones

For the overwhelming majority of us in our daily routines the experience of electricity is one of having a very versatile facility to hand in our homes. Modern life is unimaginable without electricity; it provides us with sources of light and heat in our homes, with a wondrous range of applications and devices, encompassing the simple torch, the electric kettle, a multiplicity of light fittings, radio, television, lawnmowers carpentry drills and so on and so on. All of this falls within the idea of dynamic energy; we speak of ‘current flowing’ in circuits which have a source of energy (a simple battery or a power station) all requiring ‘connections’, most often in a network of wires and cables metal, usually copper.

Coupled with our appreciation of the versatility of this facility we acknowledge that it must be treated with the utmost respect, because, unfettered, it is extremely dangerous and can cause severe damage to property and humans, even death. We have come to learn the significance of words such as ‘insulators’, which represent materials that prevent the flow of electric current and thus protect users of electrical devices. They are non-metallic, usually plastic, and even a small thickness will provide the necessary protection.

We are aware that liquids are hazardous in proximity to electricity, but we do not usually think of gases (air, most commonly) as conductors of electricity. So, a ‘live’ cable can be left dangling from a ceiling or protruding from a floor without causing harm – I hasten to add, NOT a sensible practice. This is a somewhat strange attitude because one of the most wondrous and frightening phenomena of nature – lightning – is a large-scale demonstration of the passage of electricity through gases.

It is highly likely that we have all seen earthly demonstration of electricity through gases. For instance, at night, with eyes accustomed to the darkness, it is possible to see a ‘flash’ inside a plastic electric switch when it is switched on and off. A stronger flash can be seen when the terminals of a car battery are connected by a metal bar - definitely NOT to be done intentionally, very hazardous.

The demonstration of sparking (not at all the same as the display when two cold metals strike each other) or arcing occurs between two electrodes (usually metal) that are connected to the terminals of a battery or other source of electrical energy. There is a state of ‘tension’ or difference of electric potential across the air gap between the electrodes.

Nothing visible happens in the air gap unless the difference of potential reaches a very high value or unless the size of the gap becomes very small. When either occurs the ‘tension’ is broken and the electricity jumps the gap or makes (completes) the circuit. For this to happen in air the difference of potential per centimetre of gap has to be many thousands of volts.

The breakdown of the non-conducting characteristic of air and other gases is understood in terms of the process of ionization of the air molecules. In normal circumstances of temperature and pressure the air molecules are electrically neutral, each with a balanced distribution of positive and negative charges held together by attraction. When an electrical ‘field’ is established across an air gap between two oppositely charged electrodes, the different charges within each air molecule are pulled in opposite directions to the respective electrodes. At some value of the ratio - difference of voltage over gap size - the molecules are ‘ionized’ with negative ions going to one electrode and positive ions to the other. In other words a regime of charge carriers is established and a ‘plasma’ created, made visible as a spark or arc.

Frank Llewellyn-Jones was a world authority in this branch of physics, plasma physics. He was born in Penrhiwceibr near Aberdare on September 30, 1907 and died in Swansea on February 3, 1997. After early schooling in Penrhiwceibr Primary School, he became a pupil at West Monmouth School in Pontypool. From there he won a scholarship to Merton College at Oxford University where he achieved a first class honours degree in 1929. He stayed in Oxford to do research at the Clarendon Laboratory in collaboration with Professor Sir John Townsend. It was this experience that nurtured his interest, refined his expertise and engaged his lifelong fascination with spectroscopy, ionization processes and the mechanism of the electric spark. These interests continued when he took up a lectureship in 1932 at what was then the University College (of Wales) Swansea.

During the Second World War he, like many scientists, was seconded to the War Ministry, in his case at the Royal Aircraft Establishment at Farnborough. Here he applied his knowledge of ionization phenomena to the problems encountered in fighter and high-level reconnaissance aircraft, in particular the characteristics of performance of spark-plugs and magnetic contacts.

On his return to Swansea in 1945, as Professor and Head of the Physics Department, he established two internationally renowned research schools centred on ionization physics in gases and the physics of electrical contacts. In 1955 the first ionization physics researcher from Swansea went to work in CERN, the European Research Centre in Geneva. This connection still flourishes 60 years later.

His lecturing techniques to undergraduates was more in the vein of presentations to enthuse interest in the subject rather than models of didactic exposition. He was quite unable to stick to lecture notes. He would cast them aside and launch into a wide-ranging treatment of abstract topics which held his classes enthralled. Note-taking was impossible but his students got the message.

In parallel with his research interests Llewellyn-Jones worked vigorously in administration in the college as Dean of Science, Vice-principal and Principal. Outside college life and after retirement he gave unstintingly of his time and energy to several institutions in Swansea, such as the Royal Institution (Swansea Museum). He was an ardent supporter of the Central Wales Railway and of the Mumbles Railway, which ran along the edge of Swansea bay, labouring long against proposals to curtail and close their service.

His friend and one of his successors as professor of physics in Swansea, Colyn Grey Morgan, wrote in an obituary, "(he) was endowed with a warm and generous personality … He was transparently honest, direct and totally uncompromising on matters of principle. No sycophant … his forthright views were sometimes unwelcome by the establishment …" For those who worked with him it was remarkable that he retained his dignity and good demeanour during a bleak period in his life when his daughter died of leukaemia at the age of 16.

The author of this article is pleased to acknowledge his gratitude for the guidance he received from Llewellyn-Jones. Many others would do likewise, among them, Professor Lyn Evans, formerly Director of the Large Hadron Collider (LHC) at CERN, the Organisation européenne pour la recherche nucléaire (European Organization for Nuclear Research), based near Geneva.

Neville Evans, December 2014

 

If you enjoyed this, you'll also enjoy these by Dr Neville Evans, in his series Scientists of Wales:

 

     ERH Jones; December 2016
Elwyn Hughes
; September 2016
Gareth Roberts
; June 2016
Ezer Griffiths; March 2016

Handel Davies; December 2015
Mathematicians of Wales; September 2015

Professor Eleri Pryce; June 2015

William Robert Grove; March 2015

Frank Llewellyn-Jones; December 2014

Professor Julie Williams; September 2014

Ieuan Maddock, F.R.S.; June 2014

John Houghton, F.R.S.; March 2014

David Brunt, F.R.S.; December 2013

Professor John Beynon; September 2013

John Meurig Thomas; June 2013
Robert Recorde and William Jones; March 2013
Richard Tecwyn Williams, F.R.S; December 2012

Lyn Evans; September 2012
E G Bowen; June 2012

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