  We study an idealised plasma of fermions, coupled through an abelian gauge
force $U(1)_X$, and which is asymmetric in that the masses of the oppositely
charged species are greatly unequal. The system is dubbed PAAI, plasma
asym\'etrique, ab\'elien et id\'ealis\'e. It is argued that due to the
ferromagnetic instability that arises, the ground state gives rise to a complex
of domain walls. This complex being held together by stresses much stronger
than cosmic gravity, does not evolve with the scale factor and along with the
heavier oppositely charged partners simulates the required features of Dark
Energy with mass scale for the lighter fermions in the micro-eV to nano-eV
range. Further, residual $X$-magnetic fields through mixture with standard
magnetic fields, can provide the seed for cosmic-scale magnetic fields. Thus
the scenario can explain several cosmological puzzles including Dark Energy.
