DEVICE FOR SCANNING CHARGED PARTICLE BEAM

摘要

A device for a scanning charged particle beam comprising longitudinal and transverse scanning electromagnets (1, 4) intended for deflecting the beam, along the length and the width, respectively, of an outlet window (2), generators (5, 6) of the longitudinal and transverse scanning current supply for the electromagnets (1, 4), and a variable delay unit (7), connected between the generator (5) of longitudinal scanning current and a synchronizing input of the generator (6) of transverse scanning current and a synchronizing input of the generator (6) of transverse scanning current so that the impulses are supplied to the input of the variable delay unit (7) at the times when the current in the windings of the electromagnet (1) of longitudinal scanning reaches its maximum value. The variable delay unit (7) ensure delays N which differ from each other by //ct and which are effected alternatively, following the impulses supplied to its input, the values N and //ct being defined by the following formulas: (FORMULA) where d-the diameter of the charged particle beam fu-the frequency of the longitudinal scanning fu-the frequency of the transverse scanning, L-the value of the maximum deflection of the beam along the outlet window.