An Electrostatic Octopole

A pure electrostatic octopole is defined by the command: 5 E(LECTROSTATIC) O(CTOPOLE) <effective length $\ell$ of octopole in meter> <V_O in kV at electrode> <aperture radius G₀ in meter> ; [example: E   O   0.2   0.8   0.03 ;]