1. HT-7 ASIPP Surface Analysis of CLAM steel,EUROFER97 steel and W Irradiated in HT-7 Tokamak Qiang Li1,2 Qunying Huang1 Jinnan Yu3 Jiangang Li1 Yican Wu1 Xiaoxiong He1,2 1 Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031, CHINA 2 Hefei University of Science and Technology, Hefei, Anhui, 230039, CHINA 3 China Institute of Atomic Energy, Beijing 102413, CHINA

2. HT-7 ASIPP OUTLINE About CLAM steel,EUROFER97 steel and W Experiment procedure Sample Irradiation experiment Surface analysis Result and discussion Surface morphology Surface composition conclusion

3. HT-7 ASIPP About CLAM steel,EUROFER97 steel and W CLAM steel and EUROFER97 steel low activation ferritic/martensitic steel Good properties for thermal and neutron irradiation Being considered as structural material and the first wall material in tokamak

4. HT-7 ASIPP About CLAM steel,EUROFER97 steel and W W Refractory high-Z material High melting ponit,low vapor pressure,good thermal conductivity,high temperture strength and sputtering resistance Being considered as plasma facing components

5. HT-7 ASIPP Experiment procedure Sample Composition of CLAM steel, EUROFER97 steel ( wt ) pure multicrystal tungsten(~99.99% wt) Size:15*7*1.5 mm All samples were polished and cleaned with acetone and absolute alcohol,and then were dried by hot air. FeCrMnWSiVCTaNi CLAMBal8.850.421.500.010.200.0840.0720.02 EU97Bal8.820.371.100.0050.190.100.0680.021

6. HT-7 ASIPP Experiment procedure Irradiation experiment HT-7 tokamak medium size with limiter, and R=1.22m, a=0.285m, B T 2.2T the first wall material is 1Cr18Ni9Ti stainless steel, and the limiter material is graphite coated with SiC

7. HT-7 ASIPP Experiment procedure Sample shelf and its position in HT-7

8. HT-7 ASIPP Experiment procedure Plasma average parameters during experiment center: boundary: I p =125kA n e =1.5*10 19 m -3 T e =700eV T i =450eV All samples were irradiated by 802 shots total irradiation time is about 1200 seconds

9. HT-7 ASIPP Experiment procedure Surface analysis Scanning Electron Microscope (SEM) X-ray Photoelectron Spectroscopy (XPS)

10. HT-7 ASIPP Result and discussion Surface morphology CLAM

11. HT-7 ASIPP Result and discussion EUROFER97

12. HT-7 ASIPP Result and discussion W

13. HT-7 ASIPP Result and discussion Number and diameter of blisters it seemly equal for blister number in CLAM steel surface and EUROFER97 steel surface, and most of blister diameter is less than 1μm the blisters in W surface are very little,their diameter are more than 1μm

14. HT-7 ASIPP Result and discussion Summary The surface blisters of CLAM steel and EUROFER97 steel are very dense The blisters seemly range along line in the suface of two kinds of steels Blisters are observed in the surface of W Blisters are not observed in the surface of all samples which are far to center plasma

15. HT-7 ASIPP Result and discussion Surface composition Si Si peaks are obvious in No.2 samples surface, but it is not obvious for No.1 samples Other elements No obvious change for No.1 samples and No.2 samples

16. HT-7 ASIPP conclusion Relative to W,CLAM steel and EUROFER97 steel are more easy to blister when irradiated by plasma low activation ferritic steel can be used as fisrt wall materials when considering its plasma irradiation resistance ability If select W as the plasma facing materials,such as divertor armor, more deep researchs must be proceeded