Modifying x-ray streak cameras for operation on igniting fusion experiments.

Area of Science:

• Nuclear Fusion Science
• Plasma Physics
• High-Energy X-ray Detection

Background:

• The National Ignition Facility (NIF) achieved a historic net energy gain in a fusion experiment.
• Critical diagnostic equipment, the x-ray streak camera, experienced an electronic failure during this experiment, preventing data acquisition.
• A subsequent instrument artifact was identified in x-ray streak cameras, affecting data quality for high-energy x-ray signals.

Purpose of the Study:

• To address the failure of the x-ray streak camera during a landmark fusion experiment.
• To identify and mitigate an artifact causing background pedestal signals in x-ray streak camera data.
• To ensure reliable diagnostic measurements for future high-energy-density plasma experiments at NIF.

Main Methods:

• Replacement of a failed CCD sensor with a radiation-hardened CMOS sensor in the x-ray streak camera.
• Identification of an x-ray back-fluorescence artifact originating from the accelerating mesh in the streak tube.
• Mitigation of the artifact by limiting the photocathode's sensitive area.

Main Results:

• The modified x-ray streak camera, utilizing a CMOS sensor, has operated successfully on repeat ignition shots.
• The identified artifact, a background pedestal caused by x-ray back-fluorescence, has been effectively mitigated.
• The modifications allow for accurate measurement of bang time and burn-width in fusion experiments.

Conclusions:

• The successful replacement and modification of the x-ray streak camera ensure reliable data collection for NIF's fusion research.
• Mitigation of the x-ray artifact is crucial for accurate diagnostics of burning plasma experiments.
• These advancements support the continued pursuit of controlled fusion energy.