SLAC researchers image plasma instability relevant to fusion energy and astrophysics

SLAC National Accelerator Laboratory researchers have captured the first real time images of the current filamentation instability developing in high density plasma. The experiment relied on energetic X-rays from the Linac Coherent Light Source to penetrate the dense material and record the process at the Matter in Extreme Conditions instrument. The results were published in Nature Communications. The instability arises as a laser drives a current of hot electrons through the plasma, which then interacts with a return current of cold electrons moving in the opposite direction. This produces filament shaped structures on the micrometer scale. Images taken every 500 femtoseconds revealed the structures forming over a tiny fraction of a second. The observations also indicated that the instability generated a magnetic field measuring 1000 Tesla. Such strong fields are thought to play a role in accelerating cosmic rays within astrophysical plasmas like those around exploding stars. The new imaging approach could be applied to other plasma instabilities that affect fusion reactions. The research involved an international collaboration with contributions from Stanford University, the University of Alberta, several German institutions, the University of Lisbon, and the European X-ray Free-Electron Laser. Funding came from the Department of Energy Office of Science and SLAC's Laboratory Directed Research and Development Program.