With the arrival of megajoule class laser facilities, the features of laser-produced plasmas are evolving toward unprecedented high electron temperatures reached in the environment of a cm-scale indirect-drive Hohlraum for a few tens of nanoseconds. In this context, the need for in situ experimental characterization of the plasma parameters becomes critical in order to test hydrodynamics simulations in these novel conditions. Taking advantage of the progress achieved in the last 40 years, Thomson scattering has become a classic diagnostic in the characterization of laser produced plasmas. However, the many beam configuration of the megajoule scale experiments makes the measurements increasingly complex because the Thomson scattering signals produced by the 351 nm heaters themselves dominate the plasma emission around 263 nm, a wavelength range typically of interest when a 4ω Thomson probe is used. This paper reviews the requirements for and the potential of a 4ω Thomson scattering system to be operated on such 351 nm megajoule scale facilities in order to characterize the hot (Te > 3 keV) plasmas produced in the indirect-drive irradiation of a Hohlraum. It is found that the configuration of the diagnostic could be optimized in order to enable the detection of the ion acoustic resonances over a large domain of plasma parameters. The results for the electron plasma wave resonances are also given.

中文翻译：

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对兆焦级激光设备上的 4ω 汤姆逊散射系统的要求

随着兆焦耳级激光设备的出现，激光产生的等离子体的特征正在朝着在厘米级间接驱动空腔环境中达到数十纳秒的前所未有的高电子温度发展。在这种情况下，为了在这些新条件下测试流体动力学模拟，对等离子体参数的原位实验表征的需求变得至关重要。利用过去 40 年取得的进展，汤姆逊散射已成为表征激光产生的等离子体的经典诊断方法。然而，由于 351 nm 加热器本身产生的汤姆森散射信号主导了 263 nm 附近的等离子体发射，因此兆焦耳级实验的许多光束配置使测量变得越来越复杂，使用 4ω Thomson 探头时通常感兴趣的波长范围。本文回顾了在此类 351 nm 兆焦级设备上运行的 4ω 汤姆森散射系统的要求和潜力，以表征在间接驱动的空腔辐射中产生的热 (Te > 3 keV) 等离子体。发现可以优化诊断的配置以便能够在大的等离子体参数域上检测离子声共振。还给出了电子等离子体波共振的结果。3 keV) 等离子体在一个空腔的间接驱动照射中产生。发现可以优化诊断的配置以便能够在大的等离子体参数域上检测离子声共振。还给出了电子等离子体波共振的结果。3 keV) 等离子体在一个空腔的间接驱动照射中产生。发现可以优化诊断的配置以便能够在大的等离子体参数域上检测离子声共振。还给出了电子等离子体波共振的结果。