Electrostatic Steerers

Electrostatic steerers work on the principle of F = qE and cause the beam to deflect in one direction. Steerers are usually identified by the beam axis that they will cause a deflection on, e.g. X Steerer. A steerer consists of two parallel plates that are electrically isolated. The electric field is created by applying a voltage to the plates. An equal and opposite voltage is applied to each plate in the set to keep frige effects identical. If one plate was biased and the other held at ground the fringe effects would not be identical and there would be a focussing effect as well as a deflection. The lab has single set steerers immediately after Lens A and prior to the LE Faraday Cup, thay are called 2X and 2Y. The are also XY steerer sets that consist of pairs of X and Y steerers, the Low Eergy XY set is located between the LE Farady Cup and the accelerator. The High Energy XY set is located between Quad 1 and the Analyzer Object Slits.

The benefit of steerer pairs is that it allows the user to create an offset in the axis of the beam. This is called a dog leg. It is common for the Low Energy Steerer set to have a Y dog leg for terminal transmission.

Use of the High Energy X steerers is to be avoided when using the Analyzing Magnet as this can change the angle at which the beam enters the magnet.

A drawing and photo of the High Energy Steerer Set is provided below: