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Return To: Session S - Summaries (Saturday, 24 October)
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F. Wagner
Max-Planck-Institut für Plasmaphysik, EURATOM Association,
Garching-Greifswald, Germany
Introduction
The purpose of this report is to summarize the non-tokamak
experiments. The non-tokamaks naturally seek to establish reactor relevance.
This applies specifically to RFPs and helical systems. With LHD, a large
heliotron introduced to the international fusion community at this conference,
a large step toward a stellarator power plant has been taken. Another
potential of non-tokamaks is that they can contribute in a unique form to the
understanding of magnetic confinement and specifically to toroidal confinement
because they are not tokamaks. Most of the non-tokamaks are toroidal: helical
systems, RFPs, FRCs, CTs, dipoles and sheromaks. Mirrors, traps, foci are
non-toroidal systems. The Japan Times of Saturday, Oct. 24th 1998, the day of
the summaries, has given me the theme of my summary on non-tokamaks:
Everything is connected in life - the point is to know it and understand
it. The main line and the non-tokamaks are closely connected when it comes to
understanding.
As reported in this conference, the scope of non-tokamak devices ranges from laboratory experiments to high power fusion devices. In the area of non-tokamak experiments, where novel concepts are (nearly by definition) developed, a clear separation between experiment and theory may not always be possible because new concepts are first developed and - in case they arise interest - funded and realized. Therefore, in this report, we also summarize some of the new concepts of helical systems. The concept of quasi-symmetry has inspired novel devices.
By far, most of the non-tokamak experiments reported in this conference are helical systems followed by RFPs and Mirror devices. With TPE-RX, a new reversed-field-pinch started operation and made its first contribution. Three large RFPs in the MA-current range are now in operation.
We will summarize the major lines - mirrors, RFPs, and helical systems - because a comparative assessment is possible. There is no point in repeating the abstract of papers on individual devices that stand alone. Also non-neutral plasmas, where interesting physics is presented (e.g. the enhanced classical transport when the Debye length is larger than the gyro-radius) provides important and relevant information also for other research areas. Also in this field, a new device, PROTO-RT, which is a toroidal dipole trap with flexible field composition, was presented for the first time. The SSPX spheromak studies helicity injection and the connection of confinement and field fluctuations; the FRC studies the development of the appropriate equilibrium starting with a Q-pinch or by the merging of two spheromaks. A question is the achieved energy content and specifically, how much of the magnetic energy is transferred into kinetic energy of the ions. Of specific interest in these studies is the reconnection zone, its width in connection with the ion Larmor radius and its resistivity in relation to the Spitzer value.
IAEA 1999