The Helmholtz coils are used to create magnetic fields for deflecting electron beams and are attached to the tube holder S (1014525). The tube holder allows the coils to be set up in Helmholtz configuration or at varying distances. The resulting magnetic fields are highly uniform and can be aligned perpendicular to the axis of the tube or in co-axial alignment.
 

The two air-filled coils are made of lacquered copper wire on a plastic bobbin with connectors at both ends of the winding labelled (A) and (Z).