We have developed a method and apparatus for cooling electromagnetic lens
coils of the kind used in charged particle beams. The method and
apparatus provide not only a symmetrical cooling effect around the
optical axis of the charged particle beam, but also provide improved
uniformity of heat transfer. This improved uniformity enables control
over the optical axis of the charged particle beam within about 1 nm for
high current charged particle beam columns, wherein the current ranges
from about 100 nanoamps to about 1000 nanoamps. The use of a squat and
wide electromagnetic lens coil in combination with an essentially flat
modular cooling panel, which provides uniform cooling to the
electromagnetic lens coil, not only enables control over the optical axis
of the charged particle beam, but also provides mechanical stability for
the charged particle beam column.