Note: Diagnostic deuterium beam with an ultra-small energy spread for plasma spectroscopy.

The DINA-5M diagnostic atomic beam has been upgraded to reduce the energy spread down to 50 eV. An active voltage stabilization system introduces a chain of varistors connected in series that can be switched with the time constant of 70 μs to minimize the deviation from the reference to the high-voltage level. Using deuterium, the enhanced diagnostic beam has the current of four atomic amperes and the energy of 50 keV ± 50 eV. The primary considered application is a motional Stark effect diagnostic combined with laser-induced fluorescence, where the beam energy spread is an ultimate parameter determining the measurement performance.