Wendelstein 7-AS

[1][2] It was the first of a new class of advanced stellarators with modular coils, designed with the goal of developing a nuclear fusion reactor to generate electricity.

Wendelstein 7-AS was the first in a series of IPP stellarator experiments[4] with a modular coil system that creates the twisted magnetic fields necessary to confine the plasma.

It was designed to give the magnetic fields more degrees of freedom that allowed it shaped closer to the optimal theoretical configuration.

[5] Due to limited computing power and the need to quickly test the validity of the concept on the stellarator, only a partial optimization of the magnetic fields were carried out at Wendelstein 7-AS.

[verification needed] It was only on the successor device Wendelstein 7-X that a full optimization of the code used to generate the fields were carried out.

Top view of the magnetic coil system of the Wendelstein 7-AS. The position of the plasma in it is shown in red. The cross-section of the plasma changes five times along the ring, each from an upright elliptical shape (bottom left) to a more teardrop shape (bottom right) and back.
One of the characteristic optimized non-planar coils, exhibited in the Deutsches Museum .
A look through a vacuum window in the toroidal direction and along the plasma in W7-AS. The “cold” edge of the plasma appears bright, showing bulbous island structures in the center of the picture that press against the graphite tiles of the wall (left side). The radiated heat emitted at the hot center of the plasma tube (right side, approximately 30 cm in diameter) is near the X-ray spectrum and is invisible to the camera; the plasma therefore appears diffuse and transparent.