Novel Controller for DC Glow Discharge Cleaning of Chamber Walls in HL-2A Tokomak Fusion-Test-Reactor

A novel controller was developed and used in DC glow discharge cleaning to remove fusion fuels,low-Z impurities and residual gases adsorbed on chamber walls in HL-2 A Tokomak Fusion-Test-Reactor.The discussions focused on: i) the design principles,control algorithms and construction and adjustment;iii)the control objectives and requirements,including the flow-rate/pressure of fusion fuel and waveform/stability of DC discharge voltage;iii) the tested and evaluated results. The lab-built controller has been installed,field tested for over 2500 h in HL-2 A Tokomak.The results show that the novel controller makes the difference.To be specific,it significantly increased the discharge current stability by controlling the discharge voltage with an accuracy better than1%FS and shortened the manually stabilizing time of the discharge voltage from 90 s to less than 40 s.Most importantly,it considerably improved the cleanliness of HL-2 A Tokomak reactor.