  Reduced models for approximating the impact of kinetic electron behavior on
the transport of thermal energy and magnetic field are investigated. The
thermal flux limiter has improved agreement with Vlasov-Fokker-Planck data when
a harmonic form is used that adjusts the electron mean free path to account for
electron-electron collisions; these results apply to both unmagnetized and
magnetized plasmas. Once a magnetic field is incorporated, the mean free path
should also be modified using the electron gyroradius. A flux limiter on Nernst
advection of magnetic field is also required; a form that limits Nernst by the
same fraction as the thermal heat-flow best reproduces kinetic simulations. A
flux limiter form for the cross terms (Righi-Leduc and cross-gradient-Nernst)
are also suggested. Hohlraum simulations relevant to fusion experiments on the
National Ignition Facility are found to be sensitive to all of these details.
