Renewable first wall coatings in operating plasma devices

Experimental results on boronization in plasma shots at the T-11M tokamak and stellarator L-2M are presented. Nontoxic and nonexplosive metacarborane C2H12B10 was used in boron deposition process. Experiments at the tokamak have been carried out in shots with parameters: toroidal field ∼1–1.2 Т, plasma current Ip = 70 kA, average shot duration tp ∼ 150 ms and electron density along the central chord ne ∼ 2.5 × 1013 cm−3. The impurities in wall areas have been suppressed. High vacuum characteristics of the discharge chamber were stabilized. Stabilization of a plasma filament has improved. Experiments at the stellarator have been carried out in ohmic heating discharges with parameters: plasma current Ip = 18–20 kA, toroidal magnetic field Bo = 1.25 T, averaged electron density ne = (1.0–1.2) 1013 cm−3, central electron temperature Te = 300 eV and shot duration tp = 30–40 ms. High repeatability of experimental results was achieved. The technology developed provides an opportunity for practical production of renewable boron–carbon coatings using plasma shots in large-scale tokamaks and stellarators.