This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
 

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The correction of chromatic aberration in some cases is very important ingredient in the operation of a high energy ring accelerator. In the charged particle accelerators, time-varying fields are often used to correct the chromatic aberration. For instance, when a pulsed beam moves around the beam ring, a time-varying potential can be used to correct the variation of the particle speed. That is, at certain places in the ring the pulse is accelerated across the time-varying potential so that the slower particles arrive at a time when they get a greater acceleration and the faster particles get a smaller acceleration. This technique has not been applied in electron microscopes (EMs) yet because we have not successfully obtained an electron beam, with sufficient current and brightness, which needs sufficiently short pulses because the incident electrons typically travel for only 14 picoseconds in an electron lens at an accelerating voltage of 200 kV.