FRC fast ion distribution: stability and effects on equilibrium

Experimental FRC equilibria in TAE's C-2W experiment can be studied utilizing TAE's 2D hybrid equilibrium code which combines the thermal plasma multi-fluid description of TAE's equilibrium code [1] with a kinetic treatment of fast ions added with a MonteCarlo code (MC) through NB injection. These hybrid equilibria may be characterized by ``non-standard'' structures such as current density profiles with a radial double hump and peaks at turning points as well as an inverted fast-ion distribution function, i.e., df/dv \textgreater 0. Since an inverted population can affect the stability of the system through the generation of microinstabilites like drift-cyclotron loss-cone (DCLC) and Alfv\`{e}n-ion cyclotron (AIC), we address the effect of non-Maxwellian distribution functions on equilibrium structures, their stability, and the diagnosable signatures of these equilibria. Our investigation is carried out mainly through studies of fast ion orbits and distribution functions. \textit{[1]~L. Galeotti et al. Phys. Plasmas 18 082509 (2011)}