[en] The pumping system is a combination of 8 turbomolecular pumps with three stages pumping for HL-2A vacuum vessel, a total effective pumping speed at the vessel of 12 m³ ·s ^-1 for nitrogen. The leak detection of element and vessel is performed with inspiration, case of leak detection and two mass spectrometry. The total leak rate of vessel is bellow 1 x 10 ^-5 Pa ·m³ ·s^-1. The base pressure is 1 x 10^-5 Pa

[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%

[en] The pumping system is a combination of four turbomolecular pumps with three stages pumping for the HL-2A vacuum vessel preassembling, giving a total effective pumping speed of 6.4 m³·s^-1 (H₂) for the vessel. The leak detection of base element and the vacuum vessel is performed with helium mass spectrometer leak detector and two mass spectrometry. The total leak rate of the vessel is below 1.2 x 10^-5 Pa·m³·s^-1. The base pressure is 1.1 x 10^-4 Pa with suitable prepumping and outgassing

[en] The basic design of a reliable vacuum system for the HL-2A tokamak is presented. It consists of the main pumping system, pumping divertor and glow discharge cleaning (GDC) system. The main pumping system provides the pumping capability for the high vacuum of chamber, outgassing by baking and GDC. The pumping divertor initially realizes the pumping and control of edge particles in tokamak discharge. The GDC system ensures the good wall condition of the device. The preliminary operation and the data obtained with these systems are also presented. The base pressure is 4.6 x 10^-6 Pa, in the preliminary physical experiment operation of the HL-2A tokamak, and the total leak and outgassing rates of vacuum chamber is below 1.8 x 10^-5 Pa·m³·s^-1 in 12 hours. (author)

[en] The effects of several wall-cleaning methods in the HL-1 tokamak have been discussed, which include ECR, AC and TDC with different working gases. The clean-up rate of impurities for various wall conditions during the period of 1984-1989 is summarized, And the experimental results are analysed with the kinetic equation of gases

[en] By using 50 Hz AC discharge in a HL-1 torus filled with hydrogen or a mixed gas (hydrogen with any of the following gases: neon, krypton and xenon), the variation of the partial pressure of CH₄, H₂ and CO was investigated. The water yield in the mixed gas discharge depends on the composition of the mixed gases and there is a corresponding plateau of water yield for each mixed gas. All of the plateaus are higher than the water yield in the pure hydrogen discharge. Especially in the gas mixture of Kr and H₂, the water yield is a factor 3 higher than that in the pure H₂ discharge. The sum of the residual gas partial pressures immediately after H₂+Kr mixed gas AC (50 Hz) discharge cleaning decreases by a factor of 4 in comparison to that after pure H₂ AC (50 Hz) discharge cleaning. In addition, the rare gas in mixed gas discharge can also deplete the hydrogen in the near-surface layers and decrease the H₂ recycling coefficient R by 30%. (orig.)