Helium Collisional Radiative Model and Plasma Diagnostics by Using Infrared Spectra

2014 Fiscal Year Final Research Report

• Project/Area Number: 24540532
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Plasma science
• Research Institution: Kyoto University
• Principal Investigator: KADO Shinichiro 京都大学, エネルギー理工学研究所, 准教授 (10300732)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 近赤外スペクトル / 衝突輻射モデル / 輻射捕獲 / ダイバータ模擬装置 / MAP-II / ヘリウム分光

Outline of Final Research Achievements

In order to determine the electron density and temperature in fusion-relevant divertors and in divertor-simulating plasma facilities, the so-called "intensity ratio technique" of atomic helium line (He I) based on a collisional-radiative (CR) model has widely been used. Researchers have now recognized that the CR model will not give a correct answer unless the radiation trapping process between resonant singlet-P states and the ground state 1S is taken into consideration properly in low-temperature plasmas. I this research, we proposed a noble approach to measure the population of the single 2P states, by using a near infrared (NIR) radiative transition of singlet 2S-2P at 2058.130 nm. We developed a NIR spectrometer and success in measuring the line of interest in the MAP-II divertor simulator. The spatial distribution of the line exhibited a significant broadening in the spatial distribution, which indicates the effect of radiation trapping for the resonant state.

Free Research Field

プラズマ科学