| 研究開始時の研究の概要 |
Laser produced plasma(LPP) is generated by focusing a intense laser beam on the target.There is a growing interest in LPP as it concerns several prominent scientific and industrial applications. Despite the long history on the LPP research, experimental investigation on the dynamics of LPPs during and just after the laser irradiance have never been performed, which remains an important problem. This research is aiming at further our understanding on the LPP dynamics at this time window, by directly measure it with Collective Thomson scattering method.
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| 研究実績の概要 |
For the two years contrast, I investigated the laser produced plasma (LPP) behaviors using collective Thomson scattering (CTS) with temporal and spatial resolution of 2 ns and 50μm, respectively, at the time during the drive laser irradiation. YAG laser at 1 μm wavelength is serving as the drive laser. In the first year Carbon-LPP was measured, and the isothermal expansion of the LPP was first confirmed experimentally. In this second year Tin is mainly investigated for it is responsible for emitting narrow-band extreme ultraviolet (EUV) light at 13.5 nm wavelength for nanolithography. The electron density and temperature of Sn LPP was shown in detail when it radiates EUV light, which information has long been wanted by the EUV community.
Furthermore, the corresponding EUV spectra irradiated by Sn LPP near 13.5 nm were also be measured simultaneously using a grazing incidence spectroscopy (GIS). This system can provide spatial-resolved EUV spectra in the target-normal direction.
The results from GIS, along with the measured density/temperature, could answer the core question for atomic physics: ions at what temperature and density radiate what spectra. In addition, my experiment enables the first experimental validation of an existing atomic model, JATOM.
Looking farther, this noval approach can provide a valuable experimental benchmark for existing atomic models, assisting the refinement of more accurate and predictive models in the future.
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