Low-beta Relativistic Magnetic Reconnection Driven by Petawatt Lasers

High power laser systems have become important tools for studying physical processes that occur throughout the universe. One such fundamental process is magnetic reconnection. This process impulsively releases magnetic energy by altering magnetic field topology. Magnetic reconnection occurs in fusion-grade plasmas and is believed to be the underlying process driving solar flares. Laser-based experiments have already provided insight into the dynamics of magnetic reconnection under conditions found in the solar system and are approaching those of relevance to extreme astrophysics. Newly constructed multi-petawatt lasers, including the NSF ZEUS Laser User Facility at the University of Michigan, have entered much more energetic regimes with the potential for quantum effects to become important. This award supports the experimental and theoretical exploration of magnetic reconnection under the conditions generated by multi-petawatt lasers and the study of associated electron acceleration. This effort will extend the capabilities of multi-petawatt laser facilities for magnetized plasma experiments and provide a basis for future experiments under even more extreme conditions. The project will also provide training for graduate and undergraduate students. Enabled by newly available petawatt lasers, this project aims to extend experimental, numerical, and theoretical research on low-beta magnetic reconnection to relativistic regimes with giga-Gauss magnetic fields, directly relevant to extreme astrophysical environments surrounding pulsars and magnetars. By doing so, the project addresses the goals of NSF's "Windows on the Universe: The Era of Multi-Messenger Astrophysics" meta-program. A novel laser-driven coil platform will be developed for these studies that will leverage the full capabilities of multi-petawatt laser facilities, including the relativistic laser intensities and high shot rates. Magnetic field generation will be studied and diagnosed using laser-wakefield-accelerated electron beams that can measure strong fields at high shot rates. One of the primary goals of this project is to provide experimental access to low-beta reconnection in regimes where relativistic effects due to strong magnetization, as well as potential strong-field quantum electrodynamics effects, become important. The measured electron spectra from these experiments will be compared to current theories of particle acceleration, providing valuable insight towards understanding high energy particle generation in extreme astrophysics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.