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Acceleration and Redeposition of a Dust Particle in SOL/Divertor Plasma of HL‐2A Tokamak

Acceleration of a iron dust particle is studied in the SOL (Scrape‐Off Layer)/divertor plasma of the HL‐2A tokamak in Southwestern Institute of Physics, China, with a single‐null configuration. In this study the simplest model of the dust dynamics is applied: spherical shape of a dust, ion drag force due to Coulomb scattering and drag force due to the plasma ion absorption as dominant forces, and spontaneous charging of a dust particle to the equilibrium charge. In the outer region near the plasma‐facing wall the parallel plasma flow along the magnetic field pushes the dust particle to the divertor plates. It is clarified that the dust particle with a radius of 1mm from the top of the SOL/divertor region is accelerated up to around 100 m/s in a few hundreds milliseconds to the divertor plates. In our model even the small dust particle with 1nm size can overcome the sheath potential and redeposite on the divertor plate (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)