Plasma surface interactions
The PSI department studies the interaction at the interface between plasma and materials. Focus of the research lies on providing both theoretical and experimental support to the design and validation of plasma facing materials for the fusion experiment ITER and future devices.
ITER (www.iter.org) is a large scale (10 billion euro) international scientific experiment designed to prove the viability of fusion as a source of efficient, clean and sustainable energy. The ITER machine is based on the tokamak concept. In such a device magnetically confined plasma is heated to temperatures where fusion of light atoms occurs.The exhaust of the machine, the divertor, is subject to steady state heat fluxes of up to 10 MW m-2 and continues bombardment by neutrons. Additionally extreme transient heat fluxes can occur due to instabilities in the plasma. One of the key issues in ITER and future devices is the development of plasma facing components that provide long lifetime, low pollution of the core plasma and comply with safety regulations.
The maximum tolerable concentration of impurities in the core plasma (figure 2, right) depends on the atomic number of the element. For low atomic number (Be, C), a higher concentration is allowed. For higher atomic number (Mo, W) per atom, more energy is lost due to radiation and therefore the tolerable concentration is lower. The blue and red lines in the figure are the boundary conditions determined by the operational goal set for ITER, an energy gain of a factor 10.
Theoretical and experimental and research into the behavior of materials under these extreme conditions is essential to develop materials suitable for the divertor and other plasma facing components.
The scientific program of the PSI department is aimed towards understanding the physics of these processes; mixing of materials at the surface, changes of surface morphology (dust formation, blistering), erosion, (re-)deposition and retention of hydrogen (important for safety aspects). For experimental work the department operates the linear plasma device Pilot-PSI and Magnum-PSI that can simulate plasma conditions on the divertor.
The PSI department is divided into four groups:
Computational plasma physics low temperature
Development and application of advanced numerical and theoretical models to describe the physics of low temperature plasma and plasma surface interaction.
Plasma surface interactions – Experimental
Perform basic plasma-surface interaction research needed for the design of the plasma facing components of future fusion devices.
Low temperature plasma physics and heating
Experimental low temperature plasma physics for understanding of fusion reactor grade divertor plasma (high density, low temperature). Physics and development of plasma source and radio-frequency heating system for dense magnetized plasmas.
Plasma surface interactions – Operations
Operation of the linear plasma devices Magnum-PSI and Pilot-PSI. Investigation of plasma facing components.
The PSI research at Rijnhuizen is performed in close collaboration with its partners in the Trilateral Euregio Cluster (TEC). These partners are the FZ-Jülich and KMS/ERM-Brussels. Additionally there are several smaller national and international collaborations.
