National Laser Users Research Articles

Hohlraum fields with monoenergetic proton radiography at OMEGA.

A more complete understanding of laser-driven hohlraum plasmas is critical for the continued development and improvement of ICF experiments. In these hohlraums, self-generated electric and magnetic fields can play an important role in modifying plasma properties such as heat transport; however, the strength and distribution of electromagnetic fields in such hohlraums remain largely uncertain. To explore this question, we conducted experiments at the OMEGA laser facility, using monoenergetic proton radiography to probe laser-driven vacuum hohlraums. We then utilized reconstructive methods to recover information about proton deflections. To interpret these reconstructions, a new technique for detangling the contributions of electric and magnetic fields to proton deflections was developed. This work was supported in part by the U.S. Department of Energy, the National Laser Users' Facility, and the Laboratory for Laser Energetics.

Evolution of the Design and Fabrication of Astrophysics Targets for Turbulent Dynamo (TDYNO) Experiments on OMEGA

Highly complex targets are constructed by General Atomics for astrophysically relevant experiments conducted by the University of Chicago on the OMEGA laser facility through the National Laser Users’ Facility (NLUF) program.Several novel target components are fabricated, precision assembled, and extensively measured in support of this campaign and have evolved over the last 3 years to improve both the science and assembly. Examples include unique laser-machined polyimide grids to enhance plasma mixing at the target center, precision-micromachined cylindrical shields that also act as component spacers, drawn glass target supports to suspend physics packages at critical distances, and tilted pinholes for collimated proton radiography.Target component fabrication and evolution details for the NLUF Turbulent Dynamo (TDYNO) campaign are presented, along with precision-assembly techniques, metrology methods, and considerations for future TDYNO experiments on OMEGA.