|The risk of the anode cracking can be
reduced by cutting slots, which allow the segments to expand. The end of
each slot is radiused in order to prevent high stress levels. The slots
are cut by chemical etching.
As the photograph shows, the slots are cut at an angle. This is to ensure that the electron beam cannot bombard the glass envelope.
Plain anodes do not need to rotate during fluoroscopy, because the input power is low, but a slotted anode must be rotated, since it may happen that the anode comes to rest with the beam falling on the slot.
A small area of the rim of the anode has been polished so that a stroboscope can be used to check the speed and direction of rotation of the anode.