Streaked Sub-ps-resolution X-ray Line Shapes and Implications for Solid-density Plasma Dynamics

A high-resolution x-ray spectrometer was coupled with an ultrafast x-ray streak camera to produce time-resolved line shape spectra measured from hot, solid-density plasmas. A Bragg crystal was placed near a laser-produced plasma to maximize throughput; alignment tolerances were established by raytracing. The streak camera produced single-shot time-resolved spectra, heavily sloped due to photon time-of-flight differences, with sufficient reproducibility to accumulate photon statistics. The images are time-calibrated by the slope of streaked spectra and dewarped to generate spectra emitted at different times defined at the source. The streaked spectra demonstrate the evolution of spectral shoulders and other features on ps timescales, showing the feasibility of plasma parameter measurements on the rapid timescales necessary to study high-energy-density plasmas.

本数据集将高分辨率X射线光谱仪（high-resolution x-ray spectrometer）与超快X射线条纹相机（ultrafast x-ray streak camera）联用，获取了从热态固体密度等离子体中测得的时间分辨谱线轮廓光谱。实验中于激光产生的等离子体附近放置布拉格晶体（Bragg crystal）以最大化通光效率；通过光线追迹（raytracing）确定了系统对准公差。该条纹相机可生成单次拍摄的时间分辨光谱，因光子飞行时间差异导致光谱存在显著斜率，且具备足够的可重复性以积累光子统计数据。采集的图像通过条纹光谱的斜率完成时间校准，并经畸变校正后，还原出源端定义的不同时刻发射的光谱。所得条纹光谱展现了皮秒（ps）时间尺度下谱线肩峰及其他特征的演化过程，证明了在研究高能量密度等离子体（high-energy-density plasmas）所需的快速时间尺度上开展等离子体参数测量的可行性。