Shock convergence and mix dynamics in inertial confinement fusion

Understanding the phenomena of shock propagation and of turbulent mix induced by Rayleigh-Taylor (RT) instability growth is of critical importance for ignition and high gain in inertial confinement fusion (ICF). Capsule assembly and hot-spot formation require careful timing of multiple shocks to maximize hot-spot heating while minimizing heating of the main fuel. Unmitigated mixing of the main fuel with the hot-spot can quench hot-spot heating, resulting in reduced gain or failed ignition. Nuclear measurements of direct-drive implosions at the OMEGA laser facility were performed to study shock convergence and mix dynamics in ICF. During these studies, an unexpected scaling of experimental nuclear yields was observed in implosions of capsules filled with different mixtures of D2 and 3He. A number of possible mechanisms to cause the scaling were considered, but no dominant mechanism has been identified. Mix dynamics were studied using a novel capsule configuration that only emits D3He protons when the fuel and shell are atomically mixed. Temporal and spectral measurements of protons emitted from such capsules were used to investigate the extent and evolution of mix, and demonstrate that the time necessary for RT instabilities to induce mix results in a delay of the peak D3He reaction rate in these special capsules compared to standard capsules.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Physics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Rygg, James Ryan

Advisor dc:contributor.advisor

• Richard D. Petrasso.

• Physics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/39483

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/39483