Speaker
Description
Staging laser-plasma accelerators (LPAs) is a promising technique for reaching higher particle energies than achievable in a single LPA for future light sources and colliders. Currently, the BELLA Center is working to couple two LPA stages together, where a GeV-electron bunch accelerated in the first LPA stage is injected in the second LPA stage for post-acceleration to several GeV-energies. Because each stage is powered by an ultra-intense laser pulse, any optical component that would normally be used to couple in the second laser pulse is exposed to extremely high laser fluences. As a result, the required coupling optic will be damaged, making standard optical approaches impractical. Replenishable plasma mirrors can enable inter-stage coupling, be as close as possible to ~1Hz, and maintain a wavefront error < λ/10 to maintain laser focusability, while producing minimal debris to preserve the integrity of all components in the vicinity.
This poster reports the first comprehensive characterization of 4-octyl-4’-cyanobiphenyl (8CB) liquid crystal (LC) films under varying temperatures and wiping speeds. I will provide an overview of the working principle of our film formation “windmill” device, which consists of a polished aluminum surface with lens tissue wipers rotating over a 10 mm aperture capable of producing ultra-thin (10–50 nm) films. In the optimal temperature range of 21-22℃, films made with the windmill were characterized in a low-power diagnostic setup and produced 12-16 nm wavefront RMS, angular fluctuations of the reflected beam between 355-520 µrad, and film formation probabilities >80% up to 0.3 Hz. A recent high power campaign at the BELLA Petawatt facility supported their basic functionality as plasma mirrors.
Our presented results demonstrate that liquid crystal plasma mirrors provide reliable, low-debris, and cost-effective coupling optics for scalable, high-repetition-rate, multi-stage LPA experiments.
| Working group | WG1 |
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