Tomographic reconstruction and x-ray phase contrast imaging of inertial confinment fusion capsules with betatron x-ray radiation from a laser wakefield accelerator*

A sub-ps, sub-5 micron X-ray source is used for X-ray phase contrast imaging (XPCI) tomography of Inertial Confinement Fusion (ICF) fuel capsules. We will present results from an experiment in April 2024 at the Advanced Laser Light Source in Montreal, Canada, where we performed target metrology of ICF fuel capsules to compare current industrial methods (such as X-ray tubes) to LWFA based X-ray sources. A blowout regime betatron X-ray source with a critical energy ranging from 15-25 KeV was used to capture radiographs. Imaging each angle of the capsule enables a full tomographic reconstruction with a resolution of ~4um. The optimal resolution benchmarked is ~1um, which is high enough to demonstrate the shot-to-shot source size fluctuations of the source, so we can understand spatial and spectral stability on-shot. We use X-ray phase contrast imaging to differentiate between thin low Z layers in the ICF fuel capsule. The Fresnel-Kirchoff integral formula can be used to determine source characteristics from XPCI fringes in radiographs¹, we will also employ HADES (an X-ray tracing simulation code). Ultimately, our aim is to develop a diagnostic for not just target metrology of ICF fuel capsules, but employable to observe ICF implosions with unprecedented spatial-temporal resolution.

[1] Vargas et al, X-ray phase contrast imaging of additive manufactured structures using a laser wakefield accelerator. PPCF, 61 (2019) 054009.