Auroral electron acceleration induced by Cherenkov damped waves

We discuss afresh problem of the auroral electron acceleration based on the controversial reports by Bryant et al. [1992. Double layers are not particle accelerators. Physical Review Letters 68(1), 37-39] and Borovsky [1992. Double layers do accelerate particles in the Auroral Zone. Physical Review Letters 69(7), 1054-1056] that refer to the mechanism, which is the most plausible to accelerate auroral electrons: dc electric field generated by double layers or wave-particle interaction due to wave turbulence? Here, we show that both mechanisms are important, and what is more likely to happen in auroras is that turbulence and double layers assist each other so as to synergetically accelerate electrons.