An apparatus, including an electrodynamic mass analysis (EDMA) assembly. The EDMA assembly may include a first upper electrode, disposed above a beam axis; and a first lower electrode, disposed below the beam axis, opposite the first upper electrode, the EDMA assembly arranged to receive a first RF voltage signal at a first frequency. The apparatus may include a deflection assembly, disposed downstream to the EDMA assembly, the deflection assembly comprising a blocker, disposed along the beam axis. The apparatus may include an energy spread reducer (ESR), disposed downstream to the deflection assembly, the energy spread reducer arranged to receive a second RF voltage signal at a second frequency, twice the first frequency. The ESR may include an upper ESR electrode, disposed above the beam axis; and a lower ESR electrode, disposed below the beam axis.