Dust studies in DIII-D tokamak

D. L. Rudakov, W. P. West, M. Groth, J. H. Yu, J. A. Boedo, B. D. Bray, N. H. Brooks, M. E. Fenstermacher, E. M. Hollmann, A. W. Hyatt, S. I. Krasheninnikov, C. J. Lasnier, R. A. Moyer, A. Yu Pigarov, R. Smirnov, W. M. Solomon, C. P C Wong

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

1 Citation (Scopus)

Abstract

Studies of submicron dust using Mie scattering from Nd:YAG lasers and video data of micron to sub-millimeter sized dust on DIII-D tokamak have provided the first data of dust sources and transport during tokamak discharges. During normal operation on DIII-D dust observation rates are low, a few events per discharge or less. The net carbon content of the dust corresponds to a carbon atom density a few orders of magnitude below the core impurity density. Statistical analysis of Mie data collected over months of operation reveal correlation of increased dust rate with increased heating power and impulsive wall loading due to edge localized modes (ELMs) and disruptions. Generation of significant amounts of dust by disruptions is confirmed by the camera data. However, dust production by disruptions alone is insufficient to account for estimated in-vessel dust inventory in DIII-D. After an extended entry vent, thousands of dust particles are observed by cameras in the first 2-3 plasma discharges. Individual particles moving at velocities up to ∼300 m/s, breakup of larger particles into pieces, and collisions of particles with walls are observed. After ∼70 discharges, dust levels are reduced to a few events per discharge. In order to calibrate diagnostics and benchmark modeling, milligram amounts of micron-sized carbon dust have been injected into DIII-D discharges, leading to the core carbon density increase by a factor of 2-3. Following injection, dust trajectories in the divertor are mostly in the toroidal direction, consistent with the ion drag force. Dust from the injection is observed in the outboard midplane by a fast framing camera. The observed trajectories and velocities of the dust particles are in qualitative agreement with modeling by the 3D DustT code.

Original languageEnglish
Title of host publicationAIP Conference Proceedings
Pages55-58
Number of pages4
Volume1041
DOIs
Publication statusPublished - 2008
MoE publication typeA4 Article in a conference publication
EventInternational Conference on the Physics of Dusty Plasmas - Azores, Ponta Delgada, Portugal
Duration: 18 May 200823 May 2008
Conference number: 5

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Conference

ConferenceInternational Conference on the Physics of Dusty Plasmas
CountryPortugal
CityPonta Delgada
Period18/05/200823/05/2008

Keywords

  • DIII-D
  • DiMES
  • Dust
  • Mie scattering
  • Visible imaging

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