Jan Borburgh CERN - PS/CA Septa for the CERN PS Complex

Proton Synchrotron Division

Septa section

Mandate

Purpose

Technical data

Mandate:

Section of the PS/PO-group responsible for the study, design, manufacture, installation and maintenance of septa in the PS complex.

Purpose of septa magnets

Septa are necessary when a particle beam needs to be injected in or ejected from a circular accelerator. The purpose of the septa is to deflect the ejected beam from the circular accelerator, while not affecting the orbiting beam next to the magnet. Also the inverse can be done where an injected particle beam is deflected parallel to the circulating beam of the accelerator.
Basically two different types of septa can be distinguised: the electrostatic septum and the magnetic septum magnet.

Electrostatic Septa

The electrostatic septa will typically be used for slow extraction, taking several 100's of ms to eject the circulating beam. The electrostatic septum creates a static electric field between a thin septum foil (typically 0.1 mm) and an electrode in the direction of extraction. The orbiting beam circulates often within the metallic support of the septum foil, as to provide a field free region for this beam. Therefore the orbiting beam is not being disturbed by the electric field. More detailed information can be found in the electrostatic septum page.

Magnetic Septa

The magnetic septa can be used for example in combination with with a fast kicker magnet to realise a realise a so called 'single turn' injection or extraction. All particles then are ejected from the synchrotron in a single revolution of the synchrotron. The magnetic septum creates a magnetic field perpendicular to the direction of extraction. The magnet conductors are positioned in such a way, that virtually no leak field exists next to the magnet, as not to disturb the orbiting or accelerated beam. Although the actual extraction may take as little as the time of one synchrotron revolution (around 1 micro second), the high electric inductance obliges the magnet to be or Direct Current or pulsed with a half sine current of around 3 ms (half period time). More detailed information can be found for DC magnetic septa, pulsed magnetic septa and eddy current septa in their respective pages.

Technical data of the septa used in the PS complex

Technical data of the septa used in the PS complex is available on the WEB on the following page.

For comments and changes send e-mail to Jan Borburgh
Copyright CERN -- 14/08/2000