title: Floating potential of large dust grains in a collisionless flowing plasma.
abstract: Dust immersed in plasma quickly charges to a potential where the ion and electron currents to its surface balance; this is the floating potential. In order to accurately determine dust behavior, the floating potential must be known. The charging of dust grains that are small with respect to electron Debye length (λ(D)) may be adequately approximated using the orbital-motion-limited (OML) approach. A modified version of OML is presented for large dust grains in both stationary and flowing plasmas. This modified OML is compared with simulation and found to be in good agreement. The modified OML is applied to large grains charging under tokamak conditions and found to have an appreciable effect on the drag force.
authors.affiliation: Blackett Laboratory, Imperial College, Prince Consort Road, London, SW7 2BW, United Kingdom. cw708@ic.ac.uk
authors.forename: C T N
authors.initials: CT
authors.lastname: Willis
authors.forename: M
authors.initials: M
authors.lastname: Coppins
authors.forename: M
authors.initials: M
authors.lastname: Bacharis
authors.forename: J E
authors.initials: JE
authors.lastname: Allen