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Electrostatic RID Experiment
A.A.Panasenkov, E.D.Dlougach, V.V.Kuznetsov, V.K.Naumov, V.V.Platonov
Nuclear Fusion Institute, RRC “Kurchatov Institute”, 123182 Moscow, Russia
Abstract: The reference design of the residual ion dump (RID) for the ITER neutral beam injection
(NBI) system is based on an electrostatic deflection of the residual negative and positive ions
to in-line dump panels 1. According to 4-channels beam line concept, RID forms four narrow
(about 100 mm in width) vertical channels with the aid of 5 panels (1.8 m long and 1.7 m in
height). Two middle panels are negatively biased with about 20 kV. This concept has the
advantage of compact design with quite moderate power density (PD) load onto the panels –
peak PD is less 8 MW/m². However, such a concept has never been tested in any working
NBI system, all of them. use magnetic deflection systems with remote ion dumps.
Experimental investigation of the electrostatic RID concept is now started at the test stand
IREK in the Kurchatov Institute. This experiment uses positive ion beam and two panels (one
panel is under negative potential) which simulate the RID channel. In the ITER beam line the
RID has to work in the presence of stray magnetic field with mainly vertical component, so
the main physical question is in secondary electrons production and their behaviour in the
crossed electric and magnetic fields, that can have an influence on the high voltage holding
and state of operability. Hence, the experimental device panels are placed inside a special
magnetic system which produces rather uniform vertical magnetic field in the RID volume.
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Synopsis (pdf)