Author/Authors :
Duan، نويسنده , , X.R. and Cao، نويسنده , , Z. and Cui، نويسنده , , C.H. and Cai، نويسنده , , X. and Sun، نويسنده , , H.J. and Ding، نويسنده , , X.T. and Pan، نويسنده , , Y.D. and Wang، نويسنده , , M.X. and Yang، نويسنده , , Q.W. and Song، نويسنده , , X.M. and Liu، نويسنده , , D.Q. and Liu، نويسنده , , Y. Hong-Ji، نويسنده , , X.Q. and Cui، نويسنده , , Z.Y. and Zhou، نويسنده , , Y. and Liu، نويسنده , , Yong، نويسنده ,
Abstract :
Wall conditioning with siliconization has been performed in the HL-2A tokamak to improve the plasma performance. It was based on the plasma chemical vapor deposition by using a four-anode glow discharge cleaning system and gas mixture of 90% He + 10% SiH4. It was found that the main components of the residual gas were CO, H2 and H2O. The amount of H2O was reduced from 49.5% to 24.5%. After siliconization, the impurity fluxes released from the first wall were reduced, especially the oxygen level (till to 10%) and high z impurities like Cu were decreased significantly. The total radiated power measured by the bolometer was decreased from 70% to 35%. A high density exceeding the Greenwald limit and energy confinement improvement have been achieved. The plasma operational region of HL-2A has been effectively broadened.
Keywords :
Plasma facing material , Siliconization , Wall recycling , Density control
