Using Nuclear Fusion Reactions to Peer Inside the Core of a Dense Hot Plasma

Studies of different fusion reactions have shown unexpected plasma behavior in inertial fusion implosions.

Image courtesy of University of Rochester
The Magnetic Recoil Neutron Spectrometer on the OMEGA laser facility during operation. The MRS detector array is surrounded by ~20cm thick polyethylene shielding to reduce background. The MRS is primarily used to study nuclear reactions produced in high energy density plasmas. A second MRS is located at the National Ignition Facility.

The Science

Unusually high neutron yields have been observed in inertial fusion experiments performed at the OMEGA laser facility. These results suggest the separation of fuel isotopes is due to strong pressure gradients produced in an inertial fusion implosion.

The Impact

These observations indicate interesting plasma physics phenomena that could be relevant to ignition experiments being performed at the National Ignition Facility. This work has initiated new experimental and theoretical research focusing on plasma diffusion and plasma kinetics.


Using nuclear particle spectroscopy, developed at the Massachusetts Institute of Technology (MIT) in collaboration with the Laboratory for Laser Energetics (LLE) at the University of Rochester and Lawrence Livermore National Laboratory (LLNL), the first measurements of the Tritium-Tritium (TT) yield have been conducted with Magnetic Recoil Spectrometer (MRS) using Deuterium-Tritium (DT) implosions at the OMEGA laser facility. From these measurements, it was concluded that the TT yield is anomalously high and the Deuterium-Deuterium (DD) yield is anomalously low relative to the DT yield (see figure), which can be explained by stratification of the fuel in the core of an ICF implosion. This result has prompted new research focusing on plasma diffusion and plasma kinetics to better understand the underlying physics.


Richard Petrasso
MIT Plasma Science Fusion Center


DOE Office of Science, Fusion Energy Sciences, and NNSA


D. T. Casey et. al, “Evidence for Stratification of Deuterium-Tritium Fuel in Inertial Confinement Fusion Implosions,” Physical Review Letters 108, 075002 (2012). [DOI: 10.1103/PhysRevLett.108.075002].

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