[en] During HL-1 Tokamak discharges, the major gaseous impurities from the wall, CH₄, CO, CO₂, and H₂O, were observed with a remote controled quadrupol mass spectrometer of SZ-001 type. The mass spectra has multipeak shape. Each component has a special characteristic time. The partial pressure increases with the increase of plasma current and the decrease of limiter radius. These effects are especially striking with puffing gas. CO released principally during the discharge, and CH₄ after the discharge. With continuous gas filling, the time behaviour of the gaseous impurities at the gas filling side of the torus differs from that at the opposite side. After Taylor discharge cleaning of 30000 shorts, there was still a lot of C, O impurities on the SS movable limiter

[en] By using a cubic collector probe and the SIMS analysis technique, the deposition characteristics of metal impurities in the SOL of the HL-1 tokamak plasma have been studied. The radial, toroidal and poloidal distributions of deposited impurities and H⁺ profile measured by the cubic probe are presented, and experimental results are analysed

[en] Vacuum conditioning in the HL-1 tokamak is summarised. The gaseous impurities were reduced from 5.3 x 10^-5 Pa in 1984 to 1.1 x 10^-5 Pa in 1987. Only when the ultimate pressure is less than 1.3 x 10^-5 Pa, and the percent concentration of H₂O components less than 5%, it is suitable for initial wall conditioning of tokamak discharges. By using the GH₃₉ SS limiter, G₃ graphite limiter or sublimating Ti, the average density of C + O in HL-1 was respectively 6.1 x 10¹¹, 1.4 x 10¹² or 1.1 x 10¹² cm^-3. After sublimating Ti, O decreased nearly 24% and C nearly 16%