# Linear Plasma Device for the Study of Plasma-Surface Interactions
## 5 Conclusions  
Based on analysis of the literature and the experimental results, it can be stated that the developed experimental plasma installation KAZ-PSI is not inferior to many foreign analogs and fully complies with the requirements of simulations modeling the interaction of plasma and the materials of a fusion reactor. Studying plasma-surface interactions using a simulated plasma installation creates the possibility of justifying the selection of materials for the energetic fusion reactor, expanding the database of various aspects of plasma-surface interaction, verifying computational models, refining diagnostic techniques, etc. Therefore, the creation of simulation-plasma installations for studying the materials of fusion reactors holds paramount importance. These installations, by simulating plasma, enable scientists to replicate and study these conditions on a smaller scale, providing insights into how materials will behave in a real fusion reactor.  
The experiments conducted to investigate the changes in the microstructure of tungsten revealed that after exposure to helium plasma, the surface morphology of tungsten is changed. A relief is formed on the surface due to the sputtering by helium ions, as well as the accumulation of helium ions in the near-surface layer, leading to the formation of blisters. In the case of tungsten samples irradiated at 500 \({}^{\circ}\)C, regions of etching are observed on the surface due to the sputtering by helium ions. Meanwhile, in samples irradiated at 900 \({}^{\circ}\)C and 1300 \({}^{\circ}\)C, a significant high-relief morphology is formed on the surface, which is attributable to the blister formation and the appearance of eroded areas caused by sputtering. The formation of blisters is attributed to the creation of high-pressure regions in the lattice due to the accumulation of helium atoms, resulting in local expansions of the material and the formation of blisters on its surface. X-ray structural analysis confirmed the occurrence of mechanical stresses in tungsten after exposure to helium plasma. The results of mechanical tests showed that after irradiation at 500 \({}^{\circ}\)C, there is an increase in hardness of up to 10% and a slight decrease in elastic modulus. However, after irradiation at 900 \({}^{\circ}\)C and 1300 \({}^{\circ}\)C, both hardness and elastic modulus decrease, depending on the temperature. The results of the surface-erosion assessment for tungsten indicated that the degree of surface erosion increases with higher irradiation temperatures.  
Conceptualization, B.R.; methodology, B.R.; investigation, Z.S., A.K. and E.N.; data curation, R.A. and L.S.; writing--original draft preparation, B.R., A.K. and E.N.; writing--review and editing, B.R., Z.S., R.A. and L.S.; supervision, B.R.; project administration, B.R. All authors have read and agreed to the published version of the manuscript.  
This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant no. AP09058568).  
Not applicable.  
The authors declare no conflict of interest.