Cylindrical implosion experiments used to understand hydrodynamic instability growth
Cylindrical implosion experiments used to understand hydrodynamic instability growth lead image
Researchers use inertial confinement fusion (ICF), the heating and compressing of a target that is usually a pellet containing deuterium and tritium, as an attempt to initiate nuclear fusion. However, hydrodynamic instabilities often form during implosion, disrupting ICF.
Using cylindrical implosion experiments, Sauppe et al investigated the most common instabilities formed during ICF, Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities, with a goal of improving ICF. By using a cylindrically convergent system, the researchers found they could easily observe and identify instability growth in a converging system.
“As the gas heats up in an ICF capsule, it begins to push back on the dense shell and slows it down. Rayleigh-Taylor instability occurs, and elements of the gas are pushed outwards, while elements of the shell are pushed inwards,” said author Joshua Sauppe. “This cools the gas and limits the number of fusion reactions taking place, so mitigating this growth is key to improving performance.”
To study how instabilities form at high convergence, the group developed experiments for high-powered laser facilities.
“Our experiments are designed to allow us to directly measure instability growth as we push to higher and higher convergence ratios, providing valuable data to test our hydrodynamic theories and simulations in this relatively unexplored physics regime,” said Sauppe.
The team has begun testing their theoretical models of perturbation growth at the OMEGA laser facility in Rochester, New York. As they test higher and higher convergences, the team hopes to bring their investigation to the National Ignition Facility.
Source: “Using cylindrical implosions to investigate hydrodynamic instabilities in convergent geometry,” by J. P. Sauppe, S. Palaniyappan, E. Loomis, J. L. Kline, K. A. Flippo, and B. Srinivasan, Matter and Radiation at Extremes (2019). The article can be accessed at http://doi.org/10.1063/1.5090999 .
