Bumpy torus

Drawing of bumpy torus facility

The bumpy torus is a class of magnetic fusion energy devices that consist of a series of magnetic mirrors connected end-to-end to form a closed torus. It is based on a discovery made by a team headed by Ray Dandl at Oak Ridge National Laboratory in the 1960s.[1]

The main disadvantage of the classic magnetic mirror design is excessive plasma leakage through the two ends. The bumpy torus addresses this by connecting multiple mirrors together so fuel leaking from one mirror ends up in another. It is described as "bumpy" because the fuel ions comprising the plasma tend to concentrate inside the mirrors at a greater density than the leakage currents between mirror cells. An alternate description is that the magnetic field is narrower between the mirrors than in the center of each segment.[2] Such an arrangement is not stable on its own, and most bumpy torus designs use secondary fields or relativistic electrons to create a stable field inside the reactor.

Bumpy torus designs were an area of active research starting in the 1960s and continued until 1986 with the ELMO (ELectro Magnetic Orbit) Bumpy Torus at the Oak Ridge National Laboratory.[3] One, in particular, has been described: "Imagine a series of magnetic mirror machines placed end to end and twisted into a torus. An ion or electron that leaks out of one mirror cavity finds itself in another mirror cell. This constitutes a bumpy torus."[4] These demonstrated problems and most research on the concept has ended.

  1. ^ "ELMO Bumpy Torus: dark horse of fusion" (PDF). Nature. 285 (5759): 3. 1 May 1980. Bibcode:1980Natur.285....3.. doi:10.1038/285003a0. S2CID 52874747. Retrieved July 31, 2021.
  2. ^ "ELMO Bumpy Torus: dark horse of fusion" (PDF). Nature. 285 (5759): 3. 1 May 1980. Bibcode:1980Natur.285....3.. doi:10.1038/285003a0. S2CID 52874747. Retrieved July 31, 2021.
  3. ^ Uckan, Dandl, Hendrick, Bettis, Lidsky, McAlees, Santoro, Watts, Yeh (January 1977). "THE ELMO BUMPY TORUS (EBT) REACTOR". osti dot gov. Oak Ridge National Laboratory. Retrieved June 1, 2017.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ^ Cobble, Jim. "The ELMO Bumpy Torus Experiment, A Microwave-Driven, Steady-State Fusion Machine at ORNL" (PDF). iccworkshops dot org. Los Alamos National Laboratory, August 18, 2011. Archived from the original (PDF) on April 25, 2012. Retrieved June 1, 2017.