Properties and design of quasi-axisymmetric stellarators
10:30 - 12:00
Prof. Dr. Per Helander
IPP Greifswald und Garching
HGW S1 (Übertragung Hörsaal D2)
The possibility of magnetic confinement devices that have the same neoclassical transport properties as axisymmetric tokamaks was realised by Nührenberg and co-workers three decades ago. In quasi-axisymmetric stellarators, the magnetic strength is independent of the toroidal (Boozer) angle, the particle orbits are similar to those in a tokamak, and the drift kinetic equation is the same. In such devices, the particle orbits are thus well confined and the bootstrap current can contribute substantially to the rotational transform of the magnetic field. However, some of the rotational transform comes from external coils and the plasma is thus confined even in the absence of a toroidal plasma current. This opens the possibility for a device that is maximally similar to a tokamak but can operate in steady state, hopefully without disruptions.In this talk, I will review the theoretical background and describe the first steps that have been undertaken in Greifswald to design a new such device.