There are several Gridded Lenses in the lab. There is a Gridded Lens on each ion source. Both of these lenses are connected to the same power supply and it is called Lens B. The next Gridded Lens is after the Inflection Magnet and called Lens A. The controls for Lens A and Lens B are on the low energy side of the control console. A third Gridded Lens is located just inside the low energy tube of the accelerator. Its call the Gidded Volt Lens and the controls are just above the accelerator controls. This lens is generally not needed at high terminal values, but is useful in aiding transmission at low terminal values.
See the following paper for a description of Gridded Lenses. Lens A and Lens B are in category 2 and the tube lens is in category 3: