Progress on next generation gamma-ray Cherenkov detectors for the National Ignition Facility

Area of Science:

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

Background:

• Inertial Confinement Fusion (ICF) experiments at the National Ignition Facility (NIF) rely on diagnostics like the Gamma Reaction History (GRH_6m) for crucial measurements.
• Current diagnostics have limitations in sensitivity, temporal resolution, and energy threshold for detailed fusion reaction history and ablator areal density analysis.

Purpose of the Study:

• To report on Phase I of developing next-generation Gas Cherenkov Detectors (GCDs) for enhanced ICF diagnostics.
• To demonstrate the viability of integrating existing GCD technology into a NIF reentrant well for improved proximity to the implosion.
• To lay the groundwork for future GCD advancements, including pulse-dilation photomultiplier tubes and optimized detector designs.

Main Methods:

• Insertion of the existing coaxial GCD-3 detector into a NIF reentrant well, positioning it within 4 meters of the fusion implosion.
• Acquisition and analysis of reaction history and ablator gamma measurement data from this Phase I configuration.
• Assessment of the radiation background environment within the reentrant well.

Main Results:

• Phase I successfully demonstrated the feasibility of using a GCD in close proximity to the NIF implosion.
• The measurements provided valuable data on fusion reaction history and ablator gamma emissions.
• Results validate the planned upgrades for future GCD phases, including improved bandwidth and detector design.

Conclusions:

• The Phase I results confirm the potential of GCDs to significantly outperform current diagnostics like GRH_6m in sensitivity and temporal response.
• This work paves the way for advanced GCD systems capable of achieving ~100x greater sensitivity and ~10 ps temporal resolution.
• The findings support the development of a NIF-specific "Super" GCD informed by the characterized radiation environment.