Modeling and Simulation for Nanoparticle Plasma Jet Diagnostic Probe for Runaway Electron Beam-Plasma Interaction

The C$_{\mathrm{60}}$ nanoparticle plasma jet (NPPJ) rapid injection into a tokamak major disruption is followed by C$_{\mathrm{60}}$ gradual fragmentation along plasma-traversing path. The result is abundant C ion concentration in the core plasma enhancing the potential to probe and diagnose the runaway electrons (REs) during different phases of their dynamics. A C$_{\mathrm{60}}$/C NPPJ of \textasciitilde 75 mg, high-density (\textgreater 10$^{\mathrm{23}}$ m$^{\mathrm{-3}})$, hyper-velocity (\textgreater 4 km/s), and uniquely fast response-to-delivery time (\textasciitilde 1 ms) has been demonstrated on a test bed. It can rapidly and deeply deliver enough mass to increase electron density to \textasciitilde 2.4x10$^{\mathrm{21}}$ m$^{\mathrm{-3}}$, \textasciitilde 60 times larger than typical DIII-D pre-disruption value. We will present the results of our on-going work on: 1) self-consistent model for RE current density evolution (by Dreicer mechanism and ``avalanche'') focused on the effect of fast and deep deposition of C ions, 2) improvement of single C$_{\mathrm{60}}^{\mathrm{q+}}$ fragmenting ion penetration model through tokamak B(R)-field and post-TQ plasma, and 3) simulation of C$_{\mathrm{60}}^{\mathrm{q+}}$ PJ penetration through the DIII-D characteristic \textasciitilde 2 T B-field to the RE beam central location by using the Hybrid Electro-Magnetic 2D code (HEM-2D.