MADX tutorial: injection and extraction systems Dr Rob Apsimon Dr Öznur Mete

What you will learn You will learn to use the follow new MADX commands: – Seqedit: edit and existing sequence Don’t need to rewrite the entire sequence from scratch! – savebeta and beta0: Obtain and use beam parameters from an arbitrary point in an existing sequence Need this to match injection/extraction cells – Match constraints with macros Vastly more flexible than the normal matching routine

Add new sequence to your sequence file (ex6.seq) Set your kicker and septum strengths to zero initially Define the kicker and septum magnet as kickers

Modify your madx file Remove “stop” command from old file Define kickers and septum magnets in storage ring sequence. Use seqedit command to insert markers and magnetic elements into the storage ring.

Use savebeta to obtain beam parameters at start of injection/extraction cells

Create a macro for the extraction cell Define beam command for the extraction cell sequence Define a macro to “use” the extraction cell sequence and run the Twiss module with the beta0 command

Match with the use_macro command The kicker strength needs to be enough to clear the septum blade of the septum magnet (2 cm in this example) The septum magnet strength needs to be enough for the beam to clear the outer radius of the downstream quadrupole (1 m in this example)

Plot the horizontal position through the cell

Your beam trajectory should look like this!

Seqedit Extract – Extracts a subsequence from an existing sequence Cycle – Change the start point of the sequence Flatten – Removes drift lengths from a used sequence Move – Moves the location of one or more elements in a sequence

Seqedit Install – Inserts an element into an existing sequence Remove – Removes an element or group of elements from a sequence Replace – Replaces one or more existing elements in a sequence with new elements Reflect – Reverses the order of elements in a sequence

Seqedit: extract Define the kicker kicks Use seqedit to put in the markers “msept” and “mquad” and extract the sequence for the extraction region