Abstract
The thin membrane that holds the capsule in-place in the hohlraum is recognized as one of the most significant contributors to reduced performance in indirect drive inertial confinement fusion (ICF) experiments on the National Ignition Facility. This membrane, known as the “tent,” seeds a perturbation that is amplified by Rayleigh-Taylor and can rupture the capsule. A less damaging capsule support mechanism is under development. Possible alternatives include the micron-scale rods spanning the hohlraum width and supporting either the capsule or stiffening the fill-tube, a larger fill-tube to both fill and support the capsule, or a low-density foam layer that protects the capsule from the tent impact. Experiments are testing these support features to measure their imprint on the capsule. These experiments are revealing unexpected aspects about perturbation development in indirect drive ICF, such as the importance of shadows coming from bright spots in the hohlraum. Two dimensional and 3D models are used to explain these features and assess the impact on implosion performance. Experiments and modeling suggest that the fill-tube supported by a perpendicular rod can mount the capsule without any additional perturbation beyond that of the fill tube.
Highlights
Possible alternatives include the micron-scale rods spanning the hohlraum width and supporting either the capsule or stiffening the fill-tube, a larger fill-tube to both fill and support the capsule, or a low-density foam layer that protects the capsule from the tent impact. Experiments are testing these support features to measure their imprint on the capsule. These experiments are revealing unexpected aspects about perturbation development in indirect drive inertial confinement fusion (ICF), such as the importance of shadows coming from bright spots in the hohlraum
To obtain the conditions necessary for high fusion yield using inertial confinement on the National Ignition Facility (NIF),1 the capsule needs to be compressed by factors of 30–45Â
Past inertial confinement fusion (ICF) experiments suffered from excess instability growth that contaminated the hot-spot with high-Z ablator material and reduced the implosion performance
Summary
To obtain the conditions necessary for high fusion yield using inertial confinement on the National Ignition Facility (NIF), the capsule needs to be compressed by factors of 30–45Â. To confirm that these features were caused by the tent, an experiment was performed where the capsule was held by a 30 lm diameter stalk instead of the tent.. In the image shown here, this finger consists of DT fuel, but some simulations show significant amounts of CH ablator coming with it, which could further cool the hot spot through radiative losses.15 This is believed to be the source of the large amounts of mix observed in low-foot experiments..
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
