Properties of tungsten vapor plasma formed at conditions relevant to transient events in ITER at plasma gun facility MK-200UG

This paper presents experimental results obtained at pulsed plasma gun facility MK-200UG. Tungsten targets were irradiated by hot magnetized hydrogen plasma streams. Experimental conditions (heat loads, magnetic field, impact ions energy) were relevant to Edge Localized Modes (ELM) and mitigated disruptions in ITER. Primary attention has been focused on investigation of tungsten plasma formation, its properties and transport along the magnetic field lines. GGG At the plasma pulse duration of τ = 50 us, EUV radiation of the tungsten plasma is detected at the plasma heat load q = 0.3 MJ/m2. An effective thickness of the near-surface plasma layer, which emits in the EUV spectral band, is about Δx = 4 – 5 cm. Weak EUV radiation of tungsten is detected up to the distance of x ≈ 20 cm. The target plasma contains mainly tungsten ions of ionization state W+7 and above. It was found that the tungsten plasma velocity is about v ≈ 2·106 cm/s for a wide range of the plasma heat loads.