Thermo-Mechanically Stable Tungsten Powders as Solid Catchers for the Fast Release of Stopped Rare Isotopes

The Department of Energy (DOE) seeks useful methods of generating intense beams of reaccelerated rare isotopes for the next-generation Facility for Rare Isotope Beams (FRIB), which is currently under construction at Michigan State University. Stopping high-energy, heavy- ion reaction products in fast-release solid catchers is an important method to be developed for realizing intense beams of short-lived isotopes of elemental or molecular species. Short-lived isotopes are expected to play a key role in unraveling the mysteries of nuclear physics, nuclear astrophysics, and fundamental interactions at low energies. This project will develop refractory tungsten powders as catchers which retain open porosity after extended heating at high temperatures. The objective is to ensure that the tungsten catcher retains open paths between grains for effusion of atoms or molecules from the catcher to the ion source to harvest unused rare isotope beams. Alkalis and noble gases are targeted in these measurements. Simulations will be used as a predictive tool for the non-equilibrium processes for the transient species of interest. Phase I work will demonstrate the feasibility of processing grain-growth inhibited tungsten powders with open porosity and minimal sintering after extended heating at temperatures (15002000 C) in vacuum. On-line evaluation of select tungsten powders is also planned. Modeling refractory carbides and sulfides to optimize the selective release of specific elements as molecular sidebands is planned. Commercial Applications and Other Benefits: The immediate market need for these hot catcher materials is the DOE and installations like FRIB that have powerful and unique techniques for rare isotope production. Potential other markets include porous metals, metal foams, or metal-organic-frameworks whose applications include: filtration, flow control devices, breathers, and pressure equalizers, flame arrestors, spargers, rollers and applicators, fluidizers, gauge snubbers, and silencers.