High-precision mirror advances laser-driven particle acceleration experiments

A 305 mm diameter spherical mirror has been delivered to the GSI Helmholtz Centre for Heavy Ion Research (GSI) in Germany to support novel experiments in particle acceleration.

The mirror is used in studies of electron acceleration within medium-density gas jets, with the aim of generating x-ray and gamma ray sources for diagnostic applications in high-energy density physics. These experiments employ the Petawatt High-Energy Laser for heavy Ion eXperiments (PHELIX), a laser system capable of delivering pulses up to 1 kilojoule in energy or 500 terawatts in power.

Dr Johannes Hornung, from GSI’s Plasma Physics department, noted that the experiments require a high F-number final focusing mirror to achieve a well-defined focal spot with a long Rayleigh length, enabling extended interaction with the gas jet. Previous lower F-number optics did not meet these requirements. Optical Surfaces Ltd supplied the necessary new component according to our demanding specifications.

The mirror features a high damage threshold to withstand the intense laser pulses used, along with very high reflectivity to minimise energy loss, and a highly precise surface finish to ensure uniform energy distribution in the laser focus.

GSI’s PHELIX laser system delivers ultrashort pulses with energies up to 200 Joules within 500 femtoseconds, focused to micrometre-scale spots to reach intensities exceeding 10²¹ W/cm², suitable for laser-driven acceleration of particles ranging from protons to electrons.

More information online