Towards high-repetition rate HED science at the Matter in Extreme Conditions (MEC) instrument at the Linac Coherent Light Source (LCLS) *

The collocation of high-power lasers with an X-ray free electron laser has recently enabled ultrafast pump-probe measurements of material structural responses to ionizing radiation. To recreate extreme radiation environments, such as those in fusion reactors, higher-flux sources of ions and neutrons are required. This is one of many science cases driving a project to construct an all-new MEC facility, which will consist of a new underground cavern housing two experimental areas and three optical laser drivers: a high-power short pulse (150J, 150fs 10Hz); a 100J-class long pulse (10Hz); and a kJ long pulse. After giving an update on the upgrade, we will present preparatory single-shot experiments on laser-driven ion acceleration from cryogenic jet targets. The results show that these targets can reliably produce bright, high-energy proton and deuteron beams using the Texas Petawatt laser (135J, 135fs, 1/hour). The high-repetition rate compatibility of this target will allow us to fully optimize the ion beams using machine learning techniques and active laser–target–diagnostic feedback loops. To this end, we will briefly outline expansions of the LCLS data environment (handling, storage, processing) for experiments operating at up to 1 MHz in the context of MEC.