Speaker
Tomasz Fornal
(Department of Nuclear Fusion and Plasma Spectroscopy)
Description
Measurements of soft X-ray radiation from plasmas is a standard diagnostic which is used in many different fusion devices. Analysis of X-ray emission delivers among others, information about the electron density and temperature as well as can deliver an information about the impurity content in the plasma.
The paper describes design of the soft X-ray diagnostic, multi-foil system (MFS,) for the stellarator Wendelstein 7-X (W7-X) operated at IPP-Greifswald in Germany. The proposed diagnostic is based on a well-known foil-absorption technique which is use for the estimation of the electron temperature.
The proposed diagnostic will be composed up to eight detector arrays (for five Si detectors each) with Beryllium filters of different thickness. The proposed detectors have 150 nm dead layer, 380 µm active layer and a sensitive area of 4.6×4.6 mm. They have an electron collection time of about 5ns, a junction capacitance of 10pF (at reverse voltage UR = 50V) and a dark current below 12 nA at room temperature.
The main MFS vacuum chamber will be mounted on a suitable port (AEN20) of Wendelstein 7-X via a gate valve. The port is tilted to the horizontal position by an angle of 53.500. At the chamber entrance windows there are eight pinholes, covered by a Beryllium foil of 10 µm thickness in order to protect the detectors from ECRH stray radiation. Additionally, inside the MFS vacuum chamber, eight Beryllium filters of different thickness will be positioned to register signals in eight energy ranges as defined by filters. The preamplifiers to convert the small detector currents to a voltage signal will be directly attached to the air-side of the feedthrough flange in close vicinity to the detectors. They will consist of four printed circuit boards connected to the analog-to-digital converter via multi-wires coaxial cables.
Co-authors
Arthur Weller
(Max-Planck Institute of Plasma Physics, Wendelsteinstrasse 1, 17491 Greifswald, Germany)
Henning Thomsen
(Max-Planck Institute of Plasma Physics, Wendelsteinstrasse 1, 17491 Greifswald, Germany)
Jacek Kaczmarczyk
(Department of Nuclear Fusion and Plasma Spectroscopy, Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland)
Leszek Ryc
(Department of Nuclear Fusion and Plasma Spectroscopy, Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland)
Monika Kubkowska
(Department of Nuclear Fusion and Plasma Spectroscopy, Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland)
Slawomir Jablonski
(Department of Nuclear Fusion and Plasma Spectroscopy, Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland)
Tomasz Fornal
(Department of Nuclear Fusion and Plasma Spectroscopy, Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland)
Ulrich Neuner
(Max-Planck Institute of Plasma Physics, Wendelsteinstrasse 1, 17491 Greifswald, Germany)
Waldemar Figacz
(Department of Nuclear Fusion and Plasma Spectroscopy, Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland)
