Understanding Turbulent Ion Heating in the Oak Ridge Mirror Machine, "Burnout V"

For several years, we have been empirically producing steady-state, mirror-confined hot-ion plasmas with ${T}_{i}\ensuremath{\approx}\mathrm{a}$ few keV and ${n}_{i}\ensuremath{\approx}\frac{{10}^{13}}{{\mathrm{cm}}^{3}}$. We describe here the ion-heating mechanism, which is an instability having a fine-grained azimuthal structure covering a broad band of frequencies around ${\ensuremath{\omega}}_{\mathrm{pi}}$, having a rapid growth rate on the order of ${\ensuremath{\omega}}_{\mathrm{pi}}$, and being driven by an intense radial dc electric field. It does not require that ${T}_{e}>{T}_{i}$.