Correctors of a transfer line

[tchanwattana]

I am designing transfer lines of a synchrotron. I already have the field strength of magnets for an ideal trajectory.
Now I would like to estimate the field strength of correctors in the transfer lines. I checked and think that I can solve my problem by using &error_element to define errors and then use &steering_element and &correct to find the correctors' strength. I tried to find an example but only found an example for colse orbit correction using &closed_orbit.

How should I do in the case of transfer lines? Is it possible to have a simple example of how to find the correctors' field strength in a transfer line?

Thank you in advance for your response.

[michael_borland]

I've attached a simple example of trajectory correction.

--Michael

[tchanwattana]

Thank you for the example Michael.

I have another question on the same work. I would like to optimize emittance at the end of the transfer line. I tried using "&optimization_term term = "ex" &end", but the value showed during the computation is zero. Could you suggest how I should optimize the emittance?

Thakonwat

[tchanwattana]

I found that I forgot to uncomment "n_particles_per_bunch". It works now.

[tchanwattana]

May I ask more about the emittance in a transfer line.

Main components of my lattice are dipoles, quadrupoles and drifts. The dipoles's angle are fixed whereas all quadrupoles' fields and some drift length are variables for the optimization. From my results, the emittance (ex) changes when passing dipoles and the emittance increases from the initial value of 170 nmrad to the final value of ~300 nmrad. The 6D beam distribution was used in booster injection simulation and I got a request from my colleague to reduce the emittance to <200 nmrad. I have tried to control the final emittance using quadrupoles' fields and some drift length as &optimization_variable. The result I got is that the emittance ex can be decreased to some extent.

Should I consider ex in the optimization or should I use the corrected emittance ecx instead?

[michael_borland]

You should use the corrected emittance in the optimization, but also be sure that you are controlling the residual dispersion. In general for off-axis injection into a ring, you should match the dispersion at the end of the last septum or kicker to zero. For on-axis injection, match the dispersion to the lattice value.

--Michael