A bright point source of ultrashort hard x-rays from laser bioplasmas

TL;DR

This paper demonstrates that coating a glass surface with E. coli bacteria significantly enhances the production of ultrashort, high-energy x-rays when irradiated with intense laser pulses, due to local electric field amplification.

Contribution

It introduces a novel biological target approach to dramatically increase hard x-ray emission from laser plasmas, supported by experimental and simulation evidence.

Findings

X-ray brightness increased by over two orders of magnitude.

E. coli coating enhances local electric fields, boosting x-ray yield.

Potential for safe, high-repetition-rate x-ray sources.

Abstract

Micro and nano structures scatter light and amplify local electric fields very effectively. Energy incident as intense ultrashort laser pulses can be converted to x-rays and hot electrons more efficiently with a substrate that suitably modifies the local fields. Here we demonstrate that coating a plain glass surface with a few micron thick layer of an ubiquitous microbe, {\it Escherichia coli}, catapults the brightness of hard x-ray bremsstrahlung emission (up to 300 keV) by more than two orders of magnitude at an incident laser intensity of 10$^{16}$ W cm$^{-2}$. This increased yield is attributed to the local enhancement of electric fields around individual {\it E. coli} cells and is reproduced by detailed particle-in-cell (PIC) simulations. This combination of laser plasmas and biological targets can lead to turnkey, multi-kilohertz and environmentally safe sources of hard x-rays.