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Top: Diagnostic schematic; the aperture encodes spatial information in the neutron image, and neutrons interact with the scintillator array and produce light, which is captured by the streak camera.
Bottom left: Neutron arrival time distributions for three different ion temperatures. The hotter the plasma, the broader the neutron spectrum. Temperature information can be extracted from the width of these distributions.
Bottom center and right: Image plate and streak camera data for shot 101819. The x axis in the streak image corresponds to the time domain, and the y axis is the spatial axis.
A recent experiment on OMEGA, conducted by a team from Los Alamos National Laboratory, has achieved the first-ever, spatially resolved ion temperature measurement in an inertial confinement fusion implosion. The MixIT (Understanding Mix in Fusion Implosions through Ion Temperature Imaging) diagnostic combines neutron imaging and time-of-flight techniques to make this measurement, which had not previously been feasible. Capturing spatial variations in ion temperature across the hot spot during the thermonuclear burn will allow scientists to directly diagnose phenomena such as asymmetry and contaminant mix, both of which can degrade implosion performance. Additionally, since the ion temperature is a fundamental plasma variable, these measurements are crucial to validate radiation-hydrodynamic codes used to simulate these experiments.
The LANL MixIT team includes: Chris Danly, Carl Wilde, Emily Mendoza, Landon Tafoya, Verena Geppert-Kleinrath (Project Lead), Noah Birge, Brian Haines, Justin Jorgenson, and Petr Volegov.
LLE Collaborators: Andrew Sorce, Steve Ivancic, Joe Katz, and Tyler Burgett.
Emily Mendoza, Landon Tafoya, Andrew Sorce, and Steve Ivancic examining the polished end of the fiber optic bundle.
Above, LANL undergraduate students Emily Mendoza and Landon Tafoya. Mendoza (left) holds the MixIT neutron aperture, which encodes spatial information in the projected neutron image. Tafoya (right) holds the hardware to mount the aperture in the OMEGA target chamber.