FPN12-51

More on Tokamak Power Exhaust Technology

November 7, 2012

Removing hot plasma from a tokamak core is typically done through a magnetic exhaust channel called a "divertor." In today's experiments, the heat load on the divertor materials does not present a major challenge. However, in future tokamaks, such as ITER and power plants, the much larger heat loads will require new solutions. One promising technique, tested at today's power levels but thought to be capable of scaling to larger systems, was recently demonstrated on ASDEX Upgrade in Germany (FPN12-50).

Another innovative design, called the Snowflake Divertor, originally suggested and analyzed by Dmitri Ryutov and colleagues at the Lawrence Livermore National Laboratory (LLNL), has also been successfully tested in recent experiments at the Center for Research in Plasma Physics in Switzerland (CRPP), and at the Princeton Plasma Physics Laboratory (PPPL) and General Atomics (GA) in the United States.

The Snowflake Divertor configuration fans out the magnetic field lines in the exhaust channel into a shape resembling a snowflake, thus spreading the heat over a large enough surface to reduce the power density to what would be a manageable level for a future commercial power plant.

In addition to successful experimental tests of the configuration on a small tokamak at CRPP, tests were also successful on the larger NSTX tokamak at PPPL. More recently, successful tests were conducted on the DIII-D tokamak at General Atomics. The teams at LLNL, CRPP, PPPL, and GA received a 2012 R&D 100 Award from R&D Magazine for their work.

For more information, contact Dmitri Ryutov at ryutov1@llnl.gov