Fumihiro Koike

Collisional-radiative modeling of the $5p-5s$ spectrum of W XIV - W XVI ions

Xiaobin Ding [1], Fengling Zhang, Yang Yang [2,3], Ling Zhang [1], Fumihiro Koike [4], Izumi Murakami [5,6], Daiji Kato [5,7], Hiroyuki A Sakaue [5], Nobuyuki Nakamura [8], Chenzhong Dong [1]

Abstract

The wavelength and rate of the $5p-5s$ transition of W XIV - W XVI ions have been calculated by the relativistic configuration interaction (RCI) method with the implementation of Flexible Atomic code (FAC). A reasonable collisional-radiative model (CRM) has been constructed to simulate the $5p - 5s$ transition spectrum of W XIV - W XVI ions which had been observed in electron beam ion trap (EBIT) device. The results are in reasonable agreement with the available experimental and theoretical data, and might be applied to identify the controversial spectra. The confusion on the assignment of the ionization stage are solved in the present work.

Collisional radiative model for the M1 transition spectrum of the highly-charged W$^{54+}$ ions

Xiaobin Ding, Jiaoxia Yang, Linfan Zhu, Fumihiro Koike, Izumi Murakami, Daiji Kato [1], Hiroyuki A Sakaue [1], Nobuyuki Nakamura [1], Chenzhong Dong

Abstract

A detailed-level collisional-radiative model for the M1 transition spectrum of the Ca-like W$^{54+}$ ion as observed in an electron beam ion trap (EBIT) was constructed based on atomic data calculated by the relativistic configuration interaction method and distorted wave theory. The present calculated transition energy, rate and intensity of W$^{54+}$ M1 transitions are compared with previous theoretical and experimental values. The results are in reasonable agreement with the available experimental and theoretical data. The synthetic spectrum explained the EBIT spectrum in the 12-20 nm region, while a new possibly strong transition has been predicted to be observable with an appropriate electron beam energy. The present work provides accurate atomic data that may be used in plasma diagnostics applications.

Collisional-Radiative Model for the visible spectrum of $W^{26+}$ ions

Xiaobin Ding, Jiaxin Liu, Fumihiro Koike, Izumi Murakami, Daiji Kato, Hiroyuki A Sakaue [1], Nobuyuki Nakamura [1], Chenzhong Dong [1]

Abstract

Plasma diagnostics in magnetic confinement fusion plasmas by using visible spectrum strongly depends on the knowledge of fundamental atomic properties. A detailed collisional-radiative model of W$^{26+}$ ions has been constructed by considering radiative and electron excitation processes, in which the necessary atomic data had been calculated by relativistic configuration interaction method with the implementation of Flexible Atomic Code. The visible spectrum observed at an electron beam ion trap (EBIT) in Shanghai in the range of 332 nm to 392 nm was reproduced by present calculations. Some transition pairs of which the intensity ratio are sensitive to the electron density were selected as potential candidate of plasma diagnostics. Their electron density dependence are theoretically evaluated for the cases of EBIT plasmas and magnetic confinement fusion plasmas.