Investigation of early-time dynamics of laser-produced carbon plasma by collective Thomson scattering

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Laser-produced plasma (LPP) has been studied for over 50 years due to its relevance to several prominent scientific and industrial applications, such as inertial controlled fusion and extreme ultraviolet lithography (EUVL) for semiconductor manufacturing. Therefore, understanding the LPP characteristics during the laser irradiance is of great research interest. However, experimental studies on LPP dynamics during and soon after (< 50ns) the laser irradiance have never been performed. The major reason for this is that LPP is highly non-uniform and changes rapidly in both space (within tens of micrometers) and time (within nanoseconds), making the early LPP dynamics unclear.For the first time, we have demonstrated that such investigations are possible by utilizing the collective Thomson scattering method (CTS). It provides highly spatial and temporal resolved plasma parameters (electron density, electron temperature, and velocity field) of carbon LPPs in a 2-dimensional space, at the time delay of 0 to 14 ns after the laser peak. Additionally, we performed a 2D radiation hydrodynamic simulation under identical conditions as those used in the experiments. Therefore, the results allow for a first test of existing theoretical models and simulation codes. We found that the 1-dimensional isothermal model could better describe the LPP expansion at this early stage, rather than the well-accepted adiabatic model.