The 13th International Stellarator Workshop was held at the Australian National University in Canberra, Australia, from February 25 through March 1, 2002. Nearly 100 scientists from around the world attended.

Local arrangements were handled by:
Professor Jeffrey H. Harris (jeffrey.harris@anu.edu.au) and Ms. Helen P. Hawes (helen.hawes@anu.edu.au)

These Proceedings include highlights of the Workshop; the programme; the list of participants; the abstracts submitted by the attendees; submitted papers summarizing the work as presented by the participants in either oral or poster sessions, and the Workshop photograph.

Proceedings (list of authors and their papers)

You can access the online version of these proceedings here

Highlights of the 13th International Stellarator Workshop

The 13th International Stellarator Workshop was held at the Australian National University in Canberra, Australia, from February 25 through March 1, 2002. Nearly 100 scientists from around the world attended.

In what follows, I present some of the highlights. My selection and interpretation are inevitably subjective and incomplete, and interested readers can peruse the papers that were presented on this CD

• Results from the larger devices (LHD, W7AS, CHS, HELIOTRON-J, etc.) showed confinement of multi-keV plasmas produced with a variety of heating schemes (ECH, NBI, ICRF). Generation of large radial electric fields is common in these discharges. A key question for the future is whether even larger electric fields can further improve hot ion confinement, and how these effects compare with confinement in optimised magnetic configurations, i.e. those with orbit optimisation due to the design of their modular coils, or those in which auxiliary magnetic fields are used to improve orbit confinement.
• Results from LHD show that discharges with megawatt heating can be maintained for periods of minutes.

• Experiments on W7AS have demonstrated the feasibility of electron-Bernstein wave heating at high electron densities.
• In W7AS, local helical divertors have been shown to be effective in obtaining high-density discharges with low core radiation losses and without impurity accumulation. These results are compatible with the results of modelling studies.

• On LHD, the local island divertor coil system has been successfully used to study island formation and healing in finite-pressure discharges.
• Confinement studies over a wide range of rotational transform profiles with i > 1 in the TJ-II heliac show that when the effect of low-order resonances is excluded, confinement is close to that predicted from ISS-95 scaling with a transform dependence ~ i^0.4.
• High-b experiments on W7AS, LHD, and CHS show stable confinement of plasmas with b = 2-3%. Some MHD oscillations (probably interchanges) are observed, but these appear to have little or no effect on confinement. There is also some evidence of b self-stabilisation. In the light of these results, theoretical predictions of pressure limits seem more like guidelines than hard limits. However, ballooning instabilities in 3-D stellarator geometries are quite complex, and require considerable further study in both theory and experiment. Alfven modes remain a concern for fusion-grade plasmas with hot particle populations. Present experiments on W7AS and future work at Auburn will provide guidance on achieving stable operation in current-carrying stellarators (e.g., low R/a quasi-symmetric designs).
• There is renewed activity in developing and refining stability theory (MHD, ITG, etc) in three-dimensional systems, with increasing attention to the details of actual experiments. In the case of ballooning modes, toroidal localisation within field periods is an important feature of several theoretical treatments.
• The generation and effects of radial electric fields has become an important area of investigation in its own right-it figures in ~ 25% of the papers presented at the workshop. The presence of resonances in transform and turbulence can significantly change the Er from its neoclassically predicted values. Increasing Er to higher values using techniques such as particle loss driven by perpendicular NBI provides a possible route to increasing ion temperatures in present-generation devices.
• Experiments on a number of devices (TJ-II, CHS, H-1, W7AS, LHD and others) show that turbulence, transport, and confinement transitions are intimately linked. Results from H-1 show the effects of non-ambipolarity and zonal flows on turbulence levels and transport.
• Low-order resonances are frequently a nuisance in experiments, but have also found a role as tools for Er modification, transport barrier formation, and the formation of divertor topologies.
• Theory and configuration design efforts are aggressively exploiting quasi-symmetry in the synthesis of new configurations (W7X, NCSX, QPS, CHS-QA, HELIOTRON-J etc.). Extensive numerical optimisation of transport, equilibrium, stability, and engineering properties is now a standard feature of these design activities.
• While notable progress has been made in stellarator research overall, the world stellarator program faces important challenges in the coming years. Lead times for the construction of the next generation of devices are ~5 years, which makes maintaining continuity in research programs more difficult. The development of a compelling reactor vision based on the stellarator is an important task, especially in the context of renewed activity on the ITER tokamak project. The sharing of ideas, techniques, and results via international collaboration is more important than ever.