Scaled Tests and Simulation of Triboelectric Charging and Arc Discharge in an Expanding Dust Plume

Abstract:

The arc breakdown commonly generated in volcanic eruptions is reproduced in field experiments of rapidly expanding dust clouds driven by explosive charges. The controlled format also conveniently allows us to vary particulate content and velocities and to precisely instrument the event with radiofrequency, optical and spectral sensors. We observe electrical discharges during the turbulent phase of the cloud expansion, which we use as benchmarks to validate a multiphase 3D simulation. The simulation computes electrostatic potentials by considering the hydrodynamics, chemical kinetics and charge transport for a distribution of particle sizes entrained in the expanding gas cloud. A separate hybrid fluid/kinetic plasma code is employed to simulate the avalanche breakdown between charge pockets. Finally the propagation of radiated fields through regions of strongly dispersive partially ionized gas are computed in an electromagnetic finite element solver. Insight from the model validation may help us better understand the connection between plume dynamics and volcanic lightning. Prepared by LLNL under Contract DE-AC52-07NA27344.