  The concept of energetic particle reservoirs, essentially based on the
assumption of the presence of outer reflecting boundaries/magnetic mirrors or
diffusion barriers (deterministic) rather than on the effect of particle
diffusive propagation (stochastic) in magnetic turbulence, has been used for
decades to describe the space-extended decay phases of energetic particle
events within the fields of space physics, solar physics, and plasma physics.
Using five-dimensional time-dependent Fokker-Planck transport equation
simulations, in this work we demonstrate that the so-called particle reservoirs
are naturally explained and quantitatively reproduced by diffusion processes in
turbulent magnetic fields, without invoking the hypothesis of reflecting
boundaries. Our results strongly suggest that the so-called "reservoir" (based
on deterministic structure) should be renamed "flood" (based on stochastic
diffusion), which symbolizes an authentic shift in thinking and in pragmatic
rationale for the studies of energetic particles and relevant plasma phenomena
in heliophysics and in astrophysics.
