Collisions of slow alpha particles with molecules and surfaces (KKKÖ-1/2005)

Project Management: Prof. Dr. Friedrich AUMAYR, Institut für Allgemeine Physik, Vienna University of Technology
Duration: 2 years (beginning 2005)


Abstract

In future experiments for the development nuclear fusion reactors on the basis of magnetically confined plasmas in tokamak discharges (e.g. ITER) slow alpha particles (He2+) are produced as D-T reaction product (He ash). These alpha particles are being decelerated in collisions and heat the main plasma. Slow alpha particles can reach the outer edge and there collide with neutral species, e.g., H2 and O2. In such collisions the He2+ ions become neutralized and can escape the magnetic field. For realistic modeling of the outer edge plasma a precise knowledge of the respective charge exchange cross sections in the relevant collision energy range (10 eV - 1 keV) is necessary and shall be obtained within the present project.


Contact:
Prof. Dr. Friedrich Aumayr
Institut für Allgemeine Physik
Vienna University of Technology
Wiedner Haupstr. 8-10, 1040 Vienna
T +43 1 58801-13430
F +43 1 58801-13499
aumayr@iap.tuwien.ac.at

Improvement of OF-Copper to Tungsten Joints applicable for plasma components in the ITER Divertor (KKKÖ-8/2005)

Project Management: Dr. Bertram SCHEDLER, Plansee AG
Duration: 2 years (beginning 2005)


Abstract

More than 70% of the plasma facing surface in the Divertor of ITER is covered by Tungsten. The design for the tungsten armour can either be so-called "flat tiles" or "monoblocks", which are either cooled by a hollow bar with fins (hypervapotron) or a central tube, respectively. One of the challenges by using tungsten in this area is the fact that the heat sink to be armoured consists of the precipitation hardened CuCrZr alloy. Such a bimaterial-component has to cope with the residual stress from the manufacturing operation as well as the cyclic stress generated by the thermal gradients along the cross-section. Typical absorbed heat fluxes reach up to 10MW/m 2 during experimental operation. With respect to the absorbed heat flux values up to now all components manufactured by PLANSEE have reached the design relevant values with considerable margins. However, in most of the cases the performance has been limited by a crack propagation between the tungsten and the OF-Cu. Therefore this activity is focused on measures to optimize the tungsten to copper joint.


Contact:
Dr. Bertram Schedler
Plansee AG, 6600 Reutte
T +43 5672 600-2855
F +43 5672 600-62855
bertram.schedler@plansee.com

Optimisation of the Currently Available Transitions from CuCrZr to the Austenitic Stainless Steel 316L being forseen in the ITER Divertor (KKKÖ-9/2005)

Project Management: Dr. Bertram SCHEDLER, Plansee AG
Duration: 1 year (beginning 2005)


Abstract

Plasma Facing Components being foreseen for the divertor of ITER require tubes with transitions from copper alloys to stainless steel. Among other requirements this transition has to withstand the internal pressure, the fatigue loads and shall remain tight during operation. A typical transition is the use of a 5-10mm Ni sleeve that is joined by electron beam welding with stainless steel and CuCrZr. Others are galvanic coatings that form a tight layer to bridge the two materials. Also direct diffusion bonding or friction welding has been investigated and qualified for ITER. In constrained areas a localised, fatigue induced necking of the weakest partner could be imagined. Finally such a weak point could result in severe consequences of the whole system, like a water leak in a fusion machine. It is therefore the objective of this activity to investigate alternative solutions for such transitions, which are more robust compared to the currently known ones.


Contact:
Dr. Bertram Schedler
Plansee AG, 6600 Reutte
T +43 5672 600-2855
F +43 5672 600-62855
bertram.schedler@plansee.com

Stress Design in Tungsten Coatings (KKKÖ-10/2005)

Project Management: Prof. Dr. Gerhard DEHM, Erich Schmid Institute of Materials Science, Austrian Academy of Sciences (ÖAW)
Duration: 2 years (beginning 2005)


Abstract

Tungsten coatings deposited on steel (EUROFER and L316) or on Cu-based (CuCrZr alloy) substrates are used as a plasma-facing material in fusion devices. During service, the coatings are exposed to particle fluxes and heat loads of up to 1000ºC resulting in erosion, thermal stresses, and fatique damage. The main aim of this project is to characterize stresses and the microstructure of tungsten coatings. Together with Plansee AG (Reutte), we plan to develop a new stress design concept for the optimization of tungsten wall coatings.

This will be achieved by fulfilling the following tasks:

• thermal stresses are analyzed using in-situ X-ray diffraction and laser beam assisted methods.
• thermal stresses of the coatings will be correlated with the deposition conditions, layer thickness, microstructure, interlayer material, substrate material.
• fatigue damage and coating life time will be determined with the help of a newly constructed fatigue apparatus.

The project will help to optimise the thermo-mechanical performance, structural integrity and thermal fatigue resistance of tungsten coatings as an important plasma-facing material for fusion devices.


Contact:
Prof. Dr. Gerhard Dehm
Erich Schmid Institute of Materials Science
Austrian Academy of Sciences (ÖAW)
Jahnstrasse 12, 8700 Leoben
T +43 3842 804-112
F +43 3842 804-116
gerhard.dehm@notes.unileoben.ac.at

Installation for High Heat Flux tests of plasma facing components (HHF-Test Installation)

Project Management: Dr. Bertram SCHEDLER, Plansee AG
Duration: 1 year (beginning 2007)


Contact:
Dr. Bertram Schedler
Plansee AG, 6600 Reutte
T +43 5672 600-2855
F +43 5672 600-62855
bertram.schedler@plansee.com