Introduction to ITER Glow Discharge Cleaning PA
As one of the ITER wall conditioning method, the Glow Discharge Cleaning system (GDC) shall reduce and control impurity and hydrogenic fuel out-gassing, particularly oxygen, from plasma-facing components. 9 or 10 temporary electrodes will be used to the conditioning the Vacuum Vessel before first plasma. And then the temporary electrodes will be replaced by 7 permanent electrodes for all plasma operations. 10 sets of glow discharge power supplies and a GDC control system will be delivered by China.
The permanent electrodes are located in ITER vacuum vessel and integrated within the crowded diagnostics port plugs. The electrode head is a plasma-facing component, and the electrode will bear combined loads such as neutronic radiation, electromagnetic, seismic loads. GDC feedthrough is the key component as well as protection important components in this system, which integrates both electric and water feedthrough. Double-layer structure will be used and its interspace must be monitored.
GDC electrode in EPP12 port plug and surrounding environment
Glow Discharge Cleaning system (3.1.P6.CN.02) has been signed on December 25th, 2013 at Beijing and Cadarache.
After signature of GDC PA, the design work for temporary electrode and permanent electrode have been stepped into the track. Especially the scheme of electrode in EPP12 which would be installed into system in first batch has been designed and matched with port plug system in priority.
Model of EPP12 Permanent Electrode
Permanent Electrode in Port Plug