用于短波长RT不稳定性的莫尔条纹成像技术

Moire interferometry technique for short wavelength Rayleigh-Taylor instability

瑞利-泰勒(RT)不稳定性对内爆有十分不利的影响,在很多情况下,10μm左右的波长的小尺度扰动增长是最快的,这要求诊断设备的空间分辨好于几μm,但是现有的设备难以做到这一点。为了测量短波长的RT不稳定性,利用莫尔条纹技术的差拍放大作用,发展了莫尔条纹技术,并在“星光Ⅱ”装置上进行了莫尔干涉法的实验。采用两个周期相近10μm和12μm的光栅成像,获得了周期为60μm的清晰的莫尔条纹图像,图像放大了5倍。实验结果表明,莫尔条纹技术是可行的。

Rayleigh-Taylor （RT） instability plays a critical role in inertial confinement fusion as it causes the fuel-pusher mixing at the final stage of the implosion and may degrade the ignition and fusion burn performance. Under the most condition, the perturbation growth factor for 10μm wavelength is the fastest and it requires that the spatial resolution of the diagnostic instruments is better than 5μm. But it is almost impossible for the existing instruments. Using moire interferometry to convert short wavelength perturbations to longer wavelength perturbations as the beat, a new technique was obtained. The technique for moire interference was experimentally demonstrated on XG-Ⅱ facility. Two transmission gratings whose periods （ 10 and 12μm） are slightly different were nsed to image for X-ray source, and clear moire interference images with 60μm＇ s period were acquired. The experimental results show that the technique moire interference are feasible.