Cross-Magnetic-Field Heat Conduction in Non-neutral Plasmas

Abstract

This Letter discusses cross-magnetic-field collisional heat transport for a non-neutral plasma in the typical operating regime ${\ensuremath{\lambda}}_{D}\ensuremath{\gg}{r}_{c}$, where ${\ensuremath{\lambda}}_{D}$ is the Debye length and ${r}_{c}$ is the cyclotron radius. The dominant transport mechanism is the exchange of energy associated with velocity components parallel to the magnetic field. For a thermal gradient scale length ${L}_{T}\ensuremath{\gtrsim}100{\ensuremath{\lambda}}_{D}$, the energy exchange is dominated by interactions between particles separated by $O({\ensuremath{\lambda}}_{D})$ and yields a thermal diffusivity $\ensuremath{\chi}\ensuremath{\sim}{\ensuremath{\nu}}_{c}{\ensuremath{\lambda}}_{D}^{2}$, where ${\ensuremath{\nu}}_{c}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}n\overline{v}{b}^{2}$ is the collision frequency. The diffusivity is even larger for larger ${L}_{T}$, where the energy exchange is dominated by the emission and absorption of plasma waves.