Progress in the Development of Nanoparticle Plasma Jet for Runaway Electron Suppression

Successful suppression of runaway electrons (REs) by impurity injection requires 1 - 2 ms overall response, few to several km/s speed, enough mass with hundreds of m²/g specific surface area able to penetrate 2 - 5 T tokamak toroidal B-field over 1 - 2 m distance, with large assimilation fraction in post-TQ residual core plasma. A nanoparticle plasma jet (NPPJ) prototype demonstrated C₆₀ fullerene NPPJ (compatible w. CFC tokamaks) on test bed. Work on ITER-compatible boron nitride (BN) NPPJ is in progress. Once injected into plasma, C₆₀ and BN NP undergo fragmentation and ablative sublimation, respectively. C (from C₆₀) or B and N (from BN) ions with charge q = +1 to +6 produced in the core lead to rapid increase of Z_eff(r,t), with the effect of primary REs suppression. We report on our recent progress in theoretical modeling and numerical simulation of C₆₀ and BN NPPJ penetration and gradual mass delivery into post-TQ plasma with the following Z_eff effect on RE dynamics. The conceptual design for NPPJ specific installations to a tokamak (e.g., DIII-D) will also be presented.