188 / 2025-03-19 05:29:10

Challenges of high repetition rate experiments enabling new paths on high energy density physics

HRR, HED, Shock Wave, Debris

Recent advances in laser technology have led to the development of high-repetition-rate (HRR) facilities capable of delivering kilojoule-ns pulses with unprecedented shot frequencies. Notable examples include the L4n laser at ELI beamlines, DiPOLE100X at Eu-XFEL, and the MEC platform at LCLS. These facilities enable high-energy density (HED) physics experiments, conditions in which the energy density in matter exceeds 10¹¹ J/m³ and pressures above 1 Mbar, offering the potential for statistically significant data collection and valuable insights into matter under extreme states. Such HRR platforms, can achieve shot rates of approximately one per minute, with future advancements targeting rates closer to 1 Hz, to be compared to large-scale HED facilities such as PALS, Phelix, OMEGA, NIF, LMJ, etc. which operate at low repetition (e.g., 30 minutes per shot to max three shots per day). These improvements necessitate robust diagnostic systems and innovative target-handling techniques to support continuous operation. Diagnostics are pivotal for characterizing the behavior of matter in HED conditions, measuring parameters such as temperature, density, pressure, and the Equation of State (EOS). Advances in diagnostic tools, including Velocity Interferometry System for any Reflector (VISAR) and Photon Doppler Velocimetry (PDV), enable more precise and comprehensive data collection. However, adapting existing diagnostic methods for HRR platforms remains a challenge, as the higher shot frequency demands enhanced durability and debris management to protect equipment and maintain experimental integrity. Target systems for HRR must allow for rapid alignment and positioning while ensuring that laser impacts do not damage subsequent targets. Debris characterization is critical to safeguard diagnostics and laser optics. A preliminary experiment at the PALS facility explored these challenges, offering valuable insights despite PALS lower repetition rate.