Gamma bang time analysis at OMEGA.

Area of Science:

• Nuclear Fusion Science
• High-Energy-Density Physics
• Plasma Diagnostics

Background:

• Precise timing measurements are critical for understanding and optimizing inertial confinement fusion (ICF) experiments.
• Existing diagnostics require calibration against known timing events to ensure accuracy.

Purpose of the Study:

• To perform high-precision absolute bang time measurements using two distinct diagnostics.
• To calibrate a facility-generated laser timing fiducial based on laser-target coupling.
• To assess the potential for improved measurement precision at future facilities like the National Ignition Facility (NIF).

Main Methods:

• Utilized the gas Cherenkov detector (GCD) and gamma reaction history (GRH) diagnostic at the OMEGA laser facility.
• Employed X-ray timing measurements of laser-target coupling for calibration.
• Analyzed timing data to determine agreement between diagnostics and fiducial calibration accuracy.

Main Results:

• Achieved high precision in absolute bang time measurements, with GCD and GRH agreeing to within 5 picoseconds (ps) on average.
• Calibrated the laser timing fiducial, resulting in root-mean-square (rms) spreads of 9 ps for both GCD and GRH.
• Demonstrated that GRH diagnostic precision is expected to exceed NIF system requirements with increased fusion yields.

Conclusions:

• The GCD and GRH diagnostics provide highly consistent and precise absolute bang time measurements.
• Accurate calibration of laser timing fiducials is achievable using X-ray coupling measurements.
• The GRH diagnostic shows significant promise for future high-yield fusion experiments at facilities like NIF.