Scientists at Los Alamos National Laboratory have designed new imaging systems which will help physicists get detailed insights into the German stellarator, Wendelstein 7-X (W7-X).
The Wendelstein 7-X stellarator went online in December and provides an alternative approach to harness nuclear fusion which promises a reliable source of clean energy. The magnetic fields of the stellarator contain plasma, which is heated at 100 million degrees Celsius. Deuterium, a heavy isotope of hydrogen, fuses into helium at this temperature releasing exponential amounts of controlled energy.
Glen Wurden, of Los Alamos National Laboratory’s Plasma Physics group, began the development and installation of imaging systems while the W7-X was still being built. The imaging systems will study plasma edge effects and interactions within the armored walls of the three-dimensional magnetic geometries in the machine. The systems can be used to view the complete inner surface of the machine.
The researchers installed an infrared camera with the highest available resolution and an imaging system along the lines of sight. The imaging systems were designed for two stages of operation. In the first stage, a poloidal graphite limiter, that intercepts energy from the plasma’s edge will be observed.
The second stage involves removal of the limiters and the study of a new technique which uses magnetic island divertors to handle the energy at the plasma’s edge. Los Alamos’ imaging diagnostics will be used to observe the divertor hardware as plasma energy will be controlled over a range of pressures.
“This new stellarator uses optimized three-dimensional magnetic fields to enable continuous operation of high-performance, disruption-free deuterium plasmas,” said Wurden. “The Los Alamos-designed diagnostic system plays an integral role in this collaboration and the studies of 3D magnetic field systems, especially pertaining to plasma boundary effects.”
The stellarator is being tested with helium gas for now but the researchers will switch to hydrogen in February for more realistic experiments.
Image courtesy of Los Alamos National Laboratory