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Inverse Bremsstrahlung 과정을 활용한 고밀도 플라즈마의 전자밀도 계측 기술
김견호(Kyun-Ho Kim),봉철우(Cheolwoo Bong),박문수(Moon Soo Bak) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11
An experimental study on a method to accurately measure the spatiotemporal evolution of electron density in a highdensity plasma using a diode laser based on the inverse Bremsstrahlung process was carried out in a laser-induced plasma (LIP) produced under atmospheric pressure in air. First, the radial absorption coefficients were obtained from the tomographic reconstruction based on the absorbance traces collected along multiple, different laser paths around the plasma. Then, the temporal profiles of electron density at different radial positions within the plasma were then derived from these radial absorption coefficients. The extent of absorption of laser energy by the plasma was significant, allowing for measurements of electron densities exceeding 10<SUP>18</SUP> ㎝<SUP>−3</SUP>, while also suggesting that the method can be employed as a diagnostic tool for monitoring high-density plasmas.
가변파장 레이저흡수분광법과 레이저유도플라즈마 분광법 복합을 통한 온도장 재건
이준권(Jungwun Lee),봉철우(Cheolwoo Bong),유지형(Jihyung Yoo),박문수(Moon Soo Bak) 한국연소학회 2020 한국연소학회지 Vol.25 No.3
A new technique that reconstructs the temperature and species-concentration fields by using tunable diode laser absorption spectroscopy (TDLAS) and laser-induced breakdown spectroscopy (LIBS) is demonstrated on axisymmetric combustion fields. For two-line thermometry, the uncertainties in linestrengths of the absorption lines cause systematic errors in both temperature and species concentration estimations. Thus, in the study, the radial profile of water vapor concentration is obtained first using LIBS, assuming that the combustion is complete; then, the radial temperature profile is estimated from the radial profile of the absorption coefficient, as reconstructed from the absorbance profile obtained using TDLAS. The spectral line of water vapor at 7185.6 cm-1 is selected because its linestrength showed a monotonic decrease with the increase in temperature within the measuring temperature range. The radial profiles of temperature and water mole fraction are well-reconstructed, and the measurement error is found to be as low as 3%.