Reversed Field Pinch Historical Review (5)

The experiment ETA-BETA II (1979-89), (fig.3) (also this, as ETA-BETA I, with priority support by the European Fusion Program), in 1979 obtained the quiescent phase as in ZETA, 21 years later. The results were communicated at the 9th European Conference on Controlled Fusion and Plasma Physics, at Oxford.
The Padova experiments showed that, contrary to what many researchers thought, ZETA-like quiescent behaviour could be obtained in a relatively small apparatus, provided radiation losses were overcome and more accurate magnetic geometry and cleaner vacuum systems were present.

The results of ETA-BETA II gave a new boost to the RFP research; other new machines became operative in the U.S.A. (Los Alamos, San Diego, Madison), in Japan (Tokyo, Tsukuba) and in Europe (Culham and Stockholm).

It is very interesting to record also the speculative aspect of Taylor's theory.

"Like the RFP, the Solar Corona (fig.4) has been found to be highly dynamic. It exhibits both quasi-continuous and large amplitude quasi-periodic magnetic fluctuations. Also like the RFP, it is driven away from its preferred state by electric fields at its boundary. For the case of the RFP, this electric field is imposed by the external circuit. For the case of the Solar Corona, this field is induced by convective motions in the photosphere - the dense visible surface of the sun - that move the feet of the coronal magnetic field lines about.....
The coronal magnetic field is anchored in the photospere,...which forms the lower boundary of the coronal plasma.
In both cases,...RFP and Solar Corona, ...the resulting dynamics can be interpreted as a form of plasma relaxation. The dynamics of the Solar Corona are likely similar to those occurring in stellar coronae throughout the Universe. ...

A significant difference between relaxation in the Solar Corona and the RFP is the type of drive, or power input. In the Solar Corona the power input is greater than what is required to sustain the system against resistive diffusion. It is this excess power that drives the system away from the relaxed state.......The resulting relaxation may manifest itself as a solar flare or coronal mass ejection.

In the RFP the drive is the power supplied by the toroidal voltage that is required to maintain a steady mean field profile. This power input is just sufficient to generate the required level of MHD fluctuations necessary for the Dynamo; the system would not be sustained without this power input." [S. Ortolani, D.D. Schnack, "Magnetohydrodynamics of Plasma Relaxation", World Scientific (1993)]


A European Doctoral initiative on Fusion Science and Engineering has been undertaken among the Universities of Padova, Lisbon and Munich aiming at combining two formal participation modalities in the same Doctoral programme course.

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