T. K. Soboleva

Dust-Particle Transport in Tokamak Edge Plasmas

Dust particulates in the size range of 10nm–100μm are found in all fusion devices. Such dust can be generated during tokamak operation due to strong plasma∕material-surface interactions. Some recent experiments and theoretical estimates indicate that dust particles can provide an important source of impurities in the tokamak plasma. Moreover, dust can be a serious threat to the safety of next-step fusion devices. In this paper, recent experimental observations on dust in fusion devices are reviewed. A physical model for dust transport simulation and a newly developed code DUSTT are discussed. The DUSTT code incorporates both dust dynamics due to comprehensive dust-plasma interactions as well as the effects of dust heating, charging, and evaporation. The code tracks test dust particles in realistic plasma backgrounds as provided by edge-plasma transport codes. The results are presented for dust transport in current and next-step tokamaks. The effect of dust on divertor plasma profiles and core plasma conta...

Recent progress in understanding the behavior of dust in fusion devices

It has been known for a long time that microscopic dust appears in plasmas in fusion devices. Recently it was shown that dust can be responsible for the termination of long- discharges. Also, in ITER-scale experiments dust can pose safety problems related to its chemical activity, tritium retention and radioactive content. In particular, the presence of dust in the vacuum chamber of ITER is one of the main concerns of the ITER licensing process. Here we review recent progress in the understanding of different experimental and theoretical aspects of the physics of dust dynamics and transport in fusion plasmas and discuss the remaining issues.

Plasma-neutral gas interaction in a tokamak divertor: Effects of hydrogen molecules and plasma recombination

Abstract We investigate the influence of hydrogen molecules on plasma recombination using a collisional-radiative model for multispecies hydrogen plasmas and tokamak detached divertor parameters. The rate constant found for molecular activated recombination of a plasma can be as high as 2 × 10−10 cm3/s, confirming our pervious estimates. We investigate the effects of hydrogen molecules and plasma recombination on self-consistent plasma-neutral gas interactions in the recycling region of a tokamak divertor. We treat the plasma flow in a fluid approximation retaining the effects of plasma recombination and employing a Knudsen neutral transport model for a ‘gas box’ divertor geometry. For the model of plasma-neutral interactions we employ we find: (a) molecular activated recombination is a dominant channel of divertor plasma recombination; and (b) plasma recombination is a key element leading to a decrease in the plasma flux onto the target and substantial plasma pressure drop which are the main features of detached divertor regimes.

Dust in fusion devices: The state of theory and modeling

Dust in fusion plasma is a quickly developing field. In this paper the current states of theory and modeling of dust in fusion plasma are discussed and their results compared with available experimental data.

Modeling of Dust Particle Transport in Tokamak Plasmas

Recently, the presence of dust particles in tokamak plasma and the role of dust in material re‐deposition, core contamination, and tritium inventory brought significant attention of the fusion community. The physical model for dust transport simulation in fusion devices and the newly developed 3D code DUSTT are discussed. The DUSTT code takes into account both the dust dynamics due to dust‐plasma interactions as well as the effects of dust charging, heating and evaporation. The code allows tracking of test dust particle in realistic plasma background calculated with the edge‐plasma transport code UEDGE. The results on dust transport in NSTX, DIII‐D, and ITER tokamaks are presented. The possible effect of dust on divertor plasma parameters is analyzed. An assessment of core plasma contamination due to dust is given.