Laser safety design considerations for the EPAC 10 Hz petawatt laser system

The Extreme Photonics and Applications Centre (EPAC) is a world-leading 10 Hz petawatt laser system being built in the Central Laser Facility (CLF) at the UK’s Science and Technology Facilities Council Rutherford Appleton Laboratory. EPAC will generate extreme conditions for fundamental laser-plasma physics and high-energy (multi-GeV) electron acceleration as well as providing secondary sources for industrial research applications. The facility will house a 10 Hz, 30 fs, 30 J laser driven by the CLF’s DiPOLE pump laser that is delivered to two experimental areas with upgrade paths for further additional beamlines. Laser areas are integrated on the second floor of a new, dedicated three-floor building, and the beam is transported around the facility’s radiation shielding to the ground floor experimental areas. The purpose-built facility has been designed following the principles from the hierarchy of controls—elimination, substitution, engineering controls, administrative controls, and personal protective equipment. In this paper, we discuss the fundamental approach to laser safety undertaken as part of the facility design, considering the entire laser system chain, beam transport, and delivery. The approach to minimizing risks and fundamental hazards through the facility design, installation, and commissioning phases is outlined. The EPAC interlock systems play multiple roles, providing safety functions for both laser and ionizing radiation, employing a multilayered approach to safety using a combination of trap key and multiple Electrical/Electronic/Programmable Electronic (E/E/PE) systems to provide the required safety integrity level.