9 Alignment procedure of the Primary Column with Cesium source
The primary column tuning is described below for Cesium Cs⁺ source, negative secondary polarity, for the reference ISF file: Source HV = +10kV, sample HV = -5kV, corresponding to the highest impact energy (15keV).
It is advised to create the lower impact energy ISF files by performing an extrapolation from the high impact energy reference ISF file (using the Source HV valid and Sample HV valid functions of the Tuning program). The same tuning procedure, as described below, can then be applied for a more precise alignment. Note that the lenses and deflector values are expected to be proportional to the Source HV (except for L4, Beam Pos, and stigmators that also depend on the Sample HV).