Plasma scientists summarize the potential and challenges of plasma mass separation

Centrifuges and other chemical and physical processes separate high atomic or molecular mass materials from low mass materials. But existing technologies can be difficult or expensive to use for sources that are hard to differentiate chemically, like nuclear waste.

Currently, chemical methods are used to try to separate the high-mass radioactive portion of nuclear waste, like uranium and strontium, from the low-mass nonradioactive portion. However, this process is excruciatingly slow and creates a lot of secondary waste.

Seeking an alternative, authors Stewart Zweben, Renaud Gueroult, and Nathaniel Fisch at the Princeton Plasma Physics Laboratory want to design and build a device that would use plasma to separate high and low mass material. They believe this technology, plasma mass separation, could also be faster and cheaper than conventional separation methods for other applications, such as rare-earth element recycling.

The authors made theoretical advancements and implemented them on a small plasma device. While this device did not demonstrate useful quantities of plasma mass separation, it did exhibit many of the practical issues confronting plasma-based techniques. Motivated by this opportunity, the authors wrote a tutorial summarizing what they learned from their effort. “We wrote this tutorial for people, especially young people, who want to learn from what we tried and the problems we encountered and pick it up and try again,” said Zweben.

The authors’ tutorial offers a comprehensive overview of plasma mass separation, in the hope of helping others create a useful plasma mass separation device. They describe mechanisms of plasma mass separation, different device designs, goals of the field, a history of previous plasma mass separation experiments, and problems that should shape future research.

Source: “Plasma mass separation,” by S. J. Zweben, R. Gueroult, and N. J. Fisch, Physics of Plasmas (2018). The article can be accessed at https://doi.org/10.1063/1.5042845 .