Preliminary Design of GDC System for KTX Device
KeDa Torus for eXperiment (KTX) is a reversed field pinch magnetic confinement fusion research device whose main parameters are between in the RFX and MST. The base vacuum of KTX is 1 × 10−6 Pa. Six sets of turbomolecular pumps parallel installed in the six horizontal ports which served as the main pumping system for KTX and the diameters of the ports are 0.15 m. Before plasma discharge, glow discharge cleaning (GDC) system is applied to clean C, O and hydrocarbon impurity on the vacuum vessel (VV) surfaces of KTX. An inflation system and residual gas analyzer system are designed to supply the working gas and monitoring the effect of GDC respectively. According to the GDC experiment practice, the working gas pressure of the KTX GDC system is designed as 0.3 Pa, with average current density of 0.15 A/m2. Two sets of the GDC probes are installed in KTX horizontal ports symmetrically with interval angle of 180º and the input current of each anode is 1.6 A. According to the current density distribution, the centre of the VV cross section is the superior working area for GDC anode, a screw-nut pairs with the cooperation of bellows can transfer the anode from its storage position to its working position, and the stroke of the screw-nut pairs is 0.5 m. Based on the temperature rise calculation, the maximum equilibrium temperature of the anode during glow discharge is about 275 °C (under 200 °C baking). The thermal stresses caused by the temperature distribution on the anode’s components especially in the vacuum brazing areas are inspected during GDC process. All the simulation results show that the structure and base material of the KTX GDC anode can work normally without additional active cooling system.
KeywordsKTX GDC system Working gas Temperature rise Vacuum brazing
- 1.W. Liu, W. Ding, C. Xiao et al., Keda Torus eXperiment (KTX): A new reversed field pinch program in China, 53rd annual meeting of the APS division of plasma physics (Salt Lake City, Utah, November, 2011), pp. 14–18Google Scholar
- 2.C. Grisolia, J. Bucalossi, T. Loarer et al., Conditioning procedures in Tokamak: Tore Supra application. Vacuum 60, 147–152 (2001)Google Scholar
- 11.J. Li, J. Hu, X. Wang et al., Wall cleanings for pre-treatment on east. Chin. J. Phys. 61, 203–205 (2012)Google Scholar
- 13.W. Li, B. Li, M. Wang, J. Zeng et al., Recent progress of GIS/GDC design and manufacturing for ITER, in IAEA 22th Fusion Energy Conference, Geneva (2008)Google Scholar