On Wednesday 20 April, DIFFER performed the first material properties measurement with the institute's new ion beam facility. This is a milestone in the setting up of this new experiment, which uses a beam of fast ions to probe advanced energy materials. The ion beam facility will supply researchers from fusion, solar fuels and other materials sciences with unique insights into the processes on and below material surfaces in active energy devices.
"The first spectra represent a silicon substrate, with a thin film of silicon carbide on top", says lead engineer Miranda van den Berg. "We used elastic back scattering as a trial run of the facility and although we do not yet have a dedicated analysis chamber attached, already we can distinguish between different materials."
By increasing the energy of the ions in the beam, we scanned a resonance in the scattering cross-section of carbon in order to calibrate the energy of the ion beam. "In this case, going from higher to lower energies, you see the carbon peak developing. The highest peak can be observed by a terminal voltage of 1740 kV, in good agreement with the theoretical energy of the resonance at 1734 keV."
In next steps, the team will investigate the influence of magnetic fields on their measurements and will take steps to shield their system from stray fields. When the ion beam facility is fully operational, it will feature many different diagnostics to peer at and below material surfaces, such as Rutherford back scattering, elastic recoil detection, nuclear reaction analysis and particle induced gamma-ray emission.
Materials research for energy
DIFFER wants to position its Ion Beam Facility as a world class facility for materials and interfaces research. "The unique feature will be that we can investigate materials and processes while they are in active use", explains Van den Berg. This will enable DIFFER to investigate for the first time the unique chemistry, physics, and materials science which determines device efficiency, stability, and lifetime.
The 3.5 MV singletron accelerator at the heart of the Ion Beam Facility will first be connected to DIFFER's unique facility Magnum-PSI. This unique facility is the only laboratory experiment in the world which can expose materials to the harsh plasma conditions near the walls of fusion reactors. But flexible use is already built into the facility: a switching magnet allows the operator to direct the ion beam to multiple beam lines, and plans to connect the facility to solar fuels experiments and other materials research are already underway.
m  a  vandenberg  differ  nl (Miranda van den Berg)
Lead engineer Ion Beam Facility