https://doi.org/10.1140/epjd/s10053-025-01053-3
Regular Article - Plasma Physics
Momentum flux measurements in a negative ion beam for fusion research
1 Institute of Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 19, 24098, Kiel, Germany
2 ITER Technology & Diagnostics Division, Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748, Garching, Germany
a
trottenberg@physik.uni-kiel.de
Received:
23
April
2025
Accepted:
14
August
2025
Published online: 7 October 2025
A new method for determining the particle flux density in the beam of a neutral beam injector (NBI) for magnetically confined fusion plasmas is presented. The method uses a force probe to measure the momentum transfer from beam particles to a small target and has been applied at the BATMAN experimental facility at the MPI Garching. The experiments presented in this report are performed in the non-neutralized negative ion beam. It is found that the force measured at a distance of 1.4 m from the negative ion source correlates well with the momentum flux that is calculated from the ion energy and the averaged extracted ion current density.
Graphical abstract: Schematic of the force-probe diagnostic for momentum-flux measurements in the negative hydrogenion beam at the BATMAN facility. A water-cooled shield with a 5 mm aperture limits the beam spot on an L-shaped tungsten target mounted on an interferometric cantilever probe, enabling charge-independent local flux determination 1.4m downstream of the source
© The Author(s) 2025
modified publication 2025
Open Access
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