Controlled Nuclear Fusion Research, September 1965: Review Of Experimental Results

To my way of thinking the most significant milestone of the present meeting is the substantial body of evidence that has been presented on the hydromagnetic stabilization of open-ended systems. The success of minimum magnetic-field ('minimum-B') configurations in stabilizing a plasma marks one more area where theory and experiment in the field of plasma physics have been brought together with gratifying results. Let me go back a little into history and discuss the gradual growth of our information on hydromagnetic instabilities generally. Many of you will remember that hydromagnetic theory was applied to the self-pinched discharge in the early years of the controUed fusion programme. The predictions of this theory were very shortly fulfilled by the observations; the effects were so unmistakable that it was not difficult to compare the theory with the observations. On the streak pictures of the linear or toroidal discharges that were obtained in those early years one saw clearly the diffuse plasma column, which first contracted to a narrow filament and then started to distort and kink until finally it hit the wall. Under some conditions the plasma was observed to break up into a series of blobs like a string of sausages. Since the behaviour was exactly what the theory had predicted, it took no very great experimental wisdom to conclude that observations had confirmed theory