Exploring Astrophysically-Relevant Superadiabaticity Driven by Non-Resonant Heating in a Laboratory Magnetized Plasma

The polytropic index of electrons in a magnetized plasma is experimentally investigated in the presence of external heating and anisotropic work done on the system by the magnetic field. The measurements clearly demonstrate localized regions of superadiabatic electrons due to particle acceleration and energization through non-resonant betatron and Fermi heating processes. In regions where wave-induced heating through electron cyclotron resonance dominates, the plasma electrons behave adiabatically. The realization of superadiabaticity is universal where heating dominates the work done and has broader implications for energy exchange processes in astrophysically-relevant plasmas.