A Magneto-Hydrodynamic System for Generating High-Pressure Impluses in Spallation Targets

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) produces neutrons that allow researchers to study key material properties. Neutrons are produced by the interaction of a very short (1 µsec), highly intense (1 MW at 60 Hz) pulse of protons with a flowing bath of mercury called the target. The process deposits a large amount of thermal energy in the mercury. Because mercury has a high coefficient of thermal expansion, a high-amplitude (~10 MPa) and short-duration (1 µsec) pressure pulse is created, which causes erosion damage to the target assembly, impacting SNS target lifetime and operating costs. This project will develop a new facility that is capable of producing pressure pulses of similar magnitude and rise time to those experienced in the SNS. The approach involves the development of a magneto-hydrodynamic (MHD)-based technique to create a high-amplitude, short-duration pressure pulse. The basic principle of MHD is that an electric current passed through an electrically conductive fluid in a magnetic field gives rise to a pressure gradient via the Lorenz force. Commercial Applications and other Benefits as described by the awardee: This technology would allow the study of transient pressure waves in a variety of industrial applications, including water hammer and other flows with cavitation or other short-duration, large-magnitude pressure waves. The technology also should be applicable to the cooling and heat transfer systems of nuclear power plants, which often use liquid metals as working fluids.