Radial Density Profiles of Highly Ionized Metallic Impurity Ions in RF-Heated H-Mode Plasmas in EAST
Yunxin Cheng, Ling Zhang, S. Morita, Xiuda Yang, Ailan Hu, Wenmin Zhang, Fengling Zhang, Zong Xu, Zhenwei Wu, Qing Zang, Yanmin Duan, Shuyu Dai, Mao Wang, Handong Xu, Xiaojie Wang, Xinjun Zhang, Chengming Qin, Haiqing Liu, Liqun Hu
Abstract
Spectral intensities emitted from high-<inline-formula> <tex-math notation="LaTeX">$Z$ </tex-math></inline-formula> metal impurity ions of Fe<sup>22+</sup> at 132.91 Å, Mo<sup>30+</sup> at 115.999 Å, Mo<sup>31+</sup> at 127.868 Å, W<sup>42+</sup> at 129.41 Å, W<sup>43+</sup> at 126.29 Å, and W<sup>45+</sup> at 126.998 Å and their radial profiles have been observed in EAST plasmas using a space-resolved extreme ultraviolet (EUV) spectrometer. Local emissivity profiles of the emission lines are obtained from the line-integrated profile through the Abel inversion based on the magnetic equilibrium calculation from the equilibrium fitting (EFIT) code. Then, the density profile is analyzed for Fe<sup>22+</sup>, Mo<sup>31+</sup>, W<sup>43+</sup>, and W<sup>45+</sup> ions in the <inline-formula> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula>- and <inline-formula> <tex-math notation="LaTeX">$H$ </tex-math></inline-formula>-mode plasmas with lower hybrid wave (LHW) or electron-cyclotron-resonance (ECRH) heating using measured electron temperature and density profiles and photoemission coefficients (PECs) from the ADAS database. It is found that the density profile of Fe<sup>22+</sup>, W<sup>43+</sup>, and W<sup>45+</sup> ions has a peak value of <inline-formula> <tex-math notation="LaTeX">$0.48\times 10^{8}$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$2.34\times 10^{8}$ </tex-math></inline-formula>, and 1.55 <inline-formula> <tex-math notation="LaTeX">$\times 10^{8}$ </tex-math></inline-formula> cm<sup>−3</sup> at <inline-formula> <tex-math notation="LaTeX">$\rho$ </tex-math></inline-formula> = 0.13–0.17 in the LHW and ECRH-heated <inline-formula> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula>-mode plasmas, respectively. In the <inline-formula> <tex-math notation="LaTeX">$H$ </tex-math></inline-formula>-mode plasma with higher ECRH power, on the other hand, the peak position in the density profile outwardly shifts toward radial positions of <inline-formula> <tex-math notation="LaTeX">$\rho$ </tex-math></inline-formula> = 0.20–0.26. The density profiles also show an increase in the peak value in comparison with the <inline-formula> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula>-mode plasma case, i.e., increases to 0.7, 2.8, and <inline-formula> <tex-math notation="LaTeX">$1.7\times 10^{8}$ </tex-math></inline-formula> cm<sup>−3</sup> for Fe<sup>22+</sup>, W<sup>43+</sup>, and W<sup>45+</sup> ions, respectively. When the ICRF heating is applied to the <inline-formula> <tex-math notation="LaTeX">$H$ </tex-math></inline-formula>-mode plasma, the peak density significantly increases, i.e., 0.9, 3.6, and <inline-formula> <tex-math notation="LaTeX">$2.3\times 10^{8}$ </tex-math></inline-formula> cm<sup>−3</sup> for Fe<sup>22+</sup>, W<sup>43+</sup>, and W<sup>45+</sup> ions, respectively.