1145th General Monthly Meeting

"The overshadowed centenary - the discovery of the pinch effect in 1905"

A/Prof. Brian James, School of Physics, Sydney University.

Wednesday 2 August 2006, 6.30 for 7 pm
Conference Room 1, Darlington Centre, City Road

ABSTRACT

Attempts to harness the enormous nuclear energy available from fusing hydrogen into helium have gone on for half a century. To achieve fusion the hydrogen has to be massively compressed for a sufficient length of time for the reaction to occur. Most of the efforts have been concentrated on confining and compressing a gas discharge in hydrogen. Pulsing a massive current through such a discharge produces a magnetic field that "pinches" or constricts the discharge sufficiently to produce fusion. The problem is to engineer such a fusion reactor so that more power comes out than is required to run it. A new multi-billion-dollar machine, to be built in the south of France, is hoped to achieve this aim at last.

It is a little-known fact that the theory of the Pinch Effect was first published in our journal over 100 years ago, "Note on a Hollow Lightning Conductor Crushed by the Discharge" published in the Journal and Proceedings of the Royal Society of NSW 39 (1905) 131-8.

Come and hear how an investigation of a crushed hollow rod from a lightning conductor at a kerosene refinery in Hartley Vale in NSW led in 1905 to the first description of the Pinch Effect by James Pollock, Professor of Physics, University of Sydney and Henry Barraclough, Lecturer in Mechanical Engineering, University of Sydney. With a few diversions along the way, this talk will look at the investigation of the crushed conductor which lead to explaining the Pinch Effect and its subsequent relation to the history and current developments in nuclear fusion research.

BIOGRAPHICAL NOTES

Associate Professor Brian James is a graduate of the University of Sydney, where he obtained a PhD in plasma physics. His research area is plasma diagnostics, particularly those methods based on the use of lasers. He has held visiting appointments at the Culham Laboratory UK, UCLA, Kyushu University and Dublin City University. His current research interests are dusty plasmas and atomic beam diagnostics of fusion plasma. In relation to the latter he collaborates with the National Fusion Facility at the ANU. He is currently Head of Physics at the University of Sydney.

Report on the General Monthly Meeting by Jak Kelly

We are indebted to Brian James for bringing to our attention a seminal paper "Note on a Hollow Lightning Conductor Crushed by the Discharge" published in the Journal and Proceedings of the Royal Society of NSW 39 (1905) 131-8. It was by James Pollock, Physics and Henry Barraclough, Mechanical Engineering, both of the University of Sydney. In 1905 a copper tube from a lightning conductor at a kerosene refinery in Hartley Vale in NSW was mysteriously crushed by a lightning strike. Their paper solved the mystery as due to the crushing effect of the powerful magnetic field generated by the massive current through the pipe. This 'pinch' effect has over the last century been of importance in a number of fields, particularly the technology for generating power from hydrogen fusion. Starting from Hartley Vale we were taken on a lucid and interesting tour of the basic physics involved and on to current fusion research and its historical development.