Stochastic blur

There are two main ways in which coulomb interaction between ions manifests itself. The first is the global effect, which results from displacement of a given ion due to the combined effect of all the other ions traveling in the beam. The second is the individual random ion-ion scattering, which makes some ions suffer enough trajectory displacement that they do not arrive at their intended location. This is referred to as stochastic blur. This effect is particularly pronounced in the densest locations of the beam, namely, at the beam crossover point, usually in the field-free region between the two lenses of the column. A way to minimize stochastic blur is to increase the ion energy in the crossover as much as possible.  

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