The Matter in Extreme Conditions Upgrade (MEC-U) Project

The Matter in Extreme Conditions (MEC) instrument at LCLS pioneered the use of the hard X-ray free electron laser (XFEL) in combination with high-power optical lasers to advance High Energy Density (HED) science. Since it was commissioned in 2012 as an open-access user facility, MEC has enabled a wide range of high-profile scientific results, providing new insight into the atomic and structural properties of dynamic plasma and high-pressure material states. In 2021, DOE gave CD-1 approval for the construction of a new HED science facility with significant upgrades in the laser drivers and experimental capabilities of the present-day MEC. This one-of-a-kind facility will combine three optical laser drivers: a high-power short pulse (150J, 150fs 10Hz); a 100J-class long pulse (10Hz); and a kJ long pulse with the LCLS XFEL. This talk will provide an overview of the facility conceptual design and place it in the context of the growing field of high-power laser science.