2026.05.22

The Plasma Quantum Process Unit holds seminars to disseminate the research activities of the Unit. This time, Prof. Łukasz Syrocki (Institute of Plasma Physics and Laser Microfusion, Poland) will give a lecture titled “Quantitative Analysis of Tungsten Impurities and Zeff in W7-X Plasmas Using Spectroscopic Methods and Spectral Modeling”.

We hope many of you will join us.

【Details】

    Title: Quantitative Analysis of Tungsten Impurities and Zeff in W7-X Plasmas Using Spectroscopic Methods and Spectral Modeling

    Lecture: Prof. Łukasz Syrocki　(Institute of Plasma Physics and Laser Microfusion, Poland)

    Date: Friday, June 19, 2026: 13:00-14:00 （Hybrid: On-site + Zoom）

    Place：Seminar Room (Room 501), 5th floor, Research I Building, National Institute for Fusion Science

    ＊Please contact the person in charge to request the Zoom link.

【Abstract】

    A soft X-ray pulse height analysis (PHA) system is routinely employed in various fusion devices, including tokamaks and stellarators such as Wendelstein 7-X (W7-X). The PHA system is a diagnostic tool that provides information on impurity content and electron temperature in the plasma. Additionally, it facilitates the estimation of the average effective charge (Zeff) by comparing experimental spectra with theoretical predictions. Interpreting experimental X-ray spectra in terms of key plasma parameters requires the identification and inclusion of all relevant factors influencing the spectrum in theoretical radiation models. Therefore, for this purpose, two theoretical models were utilized: the SimXRay code, which simulates soft X-ray spectra for different plasma scenarios; and the Flexible Atomic Code (FAC), which calculates a broad range of atomic properties, including energy levels, transition probabilities for radiative transitions and autoionization, cross-sections for excitation and ionization by electron impact, and other parameters necessary for the collisional–radiative approximation. Selected signals recorded during the OP1.2b and OP2.1 W7-X experimental campaigns were analyzed to achieve agreement between observed and simulated spectra. This comparison enabled a reliable interpretation of the experimental X-ray spectra and provided detailed information about the impurity content within the plasma.

【Contact】

    Chihiro Suzuki (csuzuki (at) nifs.ac.jp)