Top: field energy levels as a function of . The colorbar is . Blue points at low f have an under-resolved Debye length that could explain the mismatch with 1/f. Bottom: field energy levels versus . We clearly see the mismatch between 1/Λ_p and the results, even if the trend is correct. The large scatter is a hint that Λ is not a relevant parameter to describe field fluctuations. Top and bottom: each point is the result from a simulation. The field energy levels are measured as the energy in the x electric field, (with α from Eq. (A.6)), divided by the kinetic energy of the superparticles,  ∑ _sp(γ_sp − 1).