Abstract: An internal combustion engine for neutron diffraction analysis is provided. The engine includes an elongated piston chamber formed from an aluminum alloy to ensure maximum neutron visibility into the combustion chamber. An elongated piston assembly reciprocates within the elongated piston chamber, the piston assembly including an upper piston joined to a lower piston. The upper piston and the lower piston are hollow, thereby reducing the reciprocating mass and increasing neutron access to the combustion chamber. The upper piston is lubricated with a neutron-transparent fluorocarbon lubricant such as perfluoropolyether (PFPE), while the lower piston and the crankcase are lubricated with hydrocarbon lubricant. The engine enables 3D and time-resolved measurements of strain, stress, and temperature, as well as phase transformation, texture, and microstructure.

Abstract: An internal combustion engine for neutron diffraction analysis is provided. The engine includes an elongated piston chamber formed from an aluminum alloy to ensure maximum neutron visibility into the combustion chamber. An elongated piston assembly reciprocates within the elongated piston chamber, the piston assembly including an upper piston joined to a lower piston. The upper piston and the lower piston are hollow, thereby reducing the reciprocating mass and increasing neutron access to the combustion chamber. The upper piston is lubricated with a neutron-transparent fluorocarbon lubricant such as perfluoropolyether (PFPE), while the lower piston and the crankcase are lubricated with hydrocarbon lubricant. The engine enables 3D and time-resolved measurements of strain, stress, and temperature, as well as phase transformation, texture, and microstructure.