# Linear Plasma Device for the Study of Plasma-Surface Interactions
## 1 Introduction  
The plasma-facing material (PFM) serves as the primary interface between the fusion plasma and the reactor structure, making it highly susceptible to severe irradiation conditions [1]. This susceptibility could constrain the availability of a fusion device utilizing magnetic confinement, such as the International Thermonuclear Experimental Reactor (ITER). Tungsten (W) is the primary material employed in the ITER divertor [2]. Additionally, producers of next-generation devices like the China Fusion Engineering Test Reactor (CFETR) [3] are considering the utilization of a fully tungsten first-wall, owing to its distinct advantages, which include high thermal conductivity, a high melting point, low tritium retention, and a low erosion rate [4]. Nevertheless, tungsten's brittleness poses a limitation as a PFM, leading to challenges in component manufacturing and the potential for operational failure at elevated temperatures and under high thermal loads [5]. Critical factorsinfluencing tungsten's performance encompass mechanical properties such as plasticity and the ductile-to-brittle transition temperature (DBTT) [5].  
Furthermore, severe irradiation conditions, including the impact of high-flux particles, thermal loads, and neutron damage, degrade the mechanical properties of W and increase its DBTT [6]. Advanced materials, based on W, with high operational characteristics that can maintain their structure even under severe irradiation conditions are needed [7]. Therefore, the study of plasma-surface interaction characteristics is a key focus of modern thermonuclear research, as it directly affects the performance, lifespan, and safety of future thermonuclear power installations. Linear plasma generators make a significant contribution to these studies, as they enable the systematic solution of complex physical problems related to plasma-wall interaction, have controllable plasma parameters and flexible target geometries, and provide good diagnostic access [8; 9; 10]. Linear plasma generators are highly effective tools for testing candidate materials for fusion reactors, and for contributing to the database on various aspects of plasma-surface interaction [11]. Interest in simulating the interactions of plasma and fusion reactor materials within simulations of gas discharge using plasma generators emerged in the last century, in the early nineteen-eighties. Ion beam facilities have already provided fundamental insights into elementary processes occurring when ions interact with the surface of a solid material, such as material sputtering, capture, and reflection of particles. With the commissioning of the full-scale ITER tokamak reactor, where all damaging factors will be thoroughly combined, the emergence of new synergistic phenomena and effects can be expected. The study of these phenomena can heavily rely on the database and physical models developed in simulation experiments.  
Among linear plasma generators, linear plasma installations with plasma generation controlled by an electron beam [12; 13; 14] have certain advantages as devices that allow the combination of plasma impacts and electron beams in tests with high thermal flux. In connection with this, a new laboratory linear plasma installation, KAZ-PSI, was developed and built for testing divertor candidate materials and conducting research on plasma-surface interactions.  
This study aims to assess the experimental capabilities of the developed linear plasma installation KAZ-PSI, and to investigate the irradiation of tungsten with helium plasma using this installation.