基于激光尾波加速的涡轮叶片高能X射线CT

Micro-focus computed tomography for turbine blade based on all-optical bremsstrahlung source

发展微焦点高能X射线源技术是实现高精度高能工业CT突破的关键,基于激光尾波加速驱动高能轫致辐射源开展了微焦点高能X射线源产生以及对涡轮叶片高能CT成像研究。利用一台20 TW钛蓝宝石超快超强激光器,通过电离注入的方式获得了(140±44)pC的高能电子束,并使用1.5 mm厚钨靶产生了累积源尺寸为25μm的高能轫致辐射X射线。利用该微焦点高能X射线源,采用基于压缩感知的CT重建算法,在获取较少角度投影(31个角度)的情况下,获得了对涡轮叶片叶榫结构的CT重建。

Computed tomography is a major technique for nondestructive detection of internal defects of dense materials and large-size devices.It is widely used in material science,railway,aerospace,national defense,military industry and other industries.At present,conventional high-energy industrial computed tomography system uses the X-ray source based on traditional thermionic RF electron gun,which can only provide millimeter source size,thus limiting its imaging spatial resolution.A high-energy micro-focus X-ray source is the key means to realize high-resolution high-energy industry computed tomography.As an emerging accelerator technology,the laser wakefield accelerator is a promising candidate for the micro-focus high-energy industrial computed tomography.This article reports experimental results of a micro-focus X-ray source based on laser wakefield acceleration and a computed tomography for a turbine blade.Using a 20 TW Ti:sapphire laser system,an electron beam with a charge of(140±44)pC is generated through ionization-induced injection,and then an all-optical bremsstrahlung X-ray source with an accumulated source size of 25μm is obtained by using a 1.5 mm tungsten target.Using this source,a preliminary compressed-sensing-based computed tomography for a turbine blade is performed.