Boron transport simulation using the ERO2.0 code for real-time wall conditioning in the large helical device

Real-time wall conditioning and recycling modification utilizing boron and boron nitride powder injections into the Large Helical Device

“…As a result there is greater toroidal uniformity of the powder distribution in the low density case as the deeper penetration allows greater homogenization. This is consistent with the findings of the predictive investigation [28] which was performed before the injection series and also matches the more limited impact of the powder injections observed in the higher density cases.…”

Line identification of boron and nitrogen emissions in EUV and VUV wavelength ranges in the impurity powder dropping experiments of LHD and its application to spectroscopic diagnostics

“…Moreover, in a previous study, a negative correlation between the edge electron density and the impurity ion temperature has been found for CII, CIII, and CIV emission lines released from intrinsic C impurity ions which originate from the sputtering of the C divertor plates in LHD [20]. Further investigation of this kind of relationship among edge plasma parameters can contribute to the validation of simulations of the edge plasmas such as three-dimensional impurity transport calculations using EMC3-EIRENE code [21]. In addition, the observable wavelength range of the 3 m normal incidence VUV spectrometer, 300-3200 Å, covers some N lines such as NIV 765.15 Å, NV (1238.82, 1242.80) Å, and NVI 1896.80 Å which have relatively large intensities as shown in figure 6.…”

Experimental study on boron distribution and transport at plasma-facing components during impurity powder dropping in the Large Helical Device

“…The spatial distribution of the BH intensity suggests that injected boron powder was transported and covered especially on the divertor plate, and the observed results agree well with the distribution of boron flux calculated by Shoji et al The temporal evolution of BH intensity also shows that the deposition amount increased linearly depending on the total injected amount of boron powder. The injection rate of the boron powder was ∼30 mg s −1 = ∼1.6 × 10 21 atoms s −1 , whereas desorption rates of BH and B + were ∼10 [18][19] and ∼10 [19][20] particles s −1 , respectively, by assuming area of the deposition region as a few m 2 in the entire device. These simple estimates suggest that about 10% of injected boron covered onto the divertor, although the estimated boron flux can contain desorbed, re-deposited and re-desorbed particles.…”

“…The distribution of hydrogen is very complicated, since it depends on physical parameters of the plasmas and the surface, wall structure, wall materials, and so on. Shoji et al [19,20] investigated boron transport supplied by the IPD using a three dimensional plasma fluid and the kinetic neutral edge transport Monte Carlo code (EMC3-EIRENE), coupled with a dust transport simulation code and a three-dimensional simulation by the Monte-Carlo impurity transport and plasma surface interaction code (ERO2.0) for LHD plasmas. They predicted trajectories of dropped granules into the plasma, and identified regions of high plasma flux and neutral particle density in the inboard side divertor of the torus.…”