Elegant users forum

Dear all,
I have a RF section and a couple of quads in front of a double-dogleg section. My goal is to minimize the betax (i.e. find the waist) at the third dipole using the quads upstream and the RF chirp. What optimization term should i use in elegant to do this?

regards,
Charles

Charles,

You need to first place a MARK element at the location where you want to do the fitting, e.g.,

M1: MARK,FITPOINT=1
BL: line=(...,B3,M1,...)

In the command file, use an optimization term like
&optimization_term
term = "M1#1.betax 2 .1 segt"
&end

This will constrain betax at the first occurrence ("#1") of M1 to be less than 2 with a tolerance of 0.1. The manual has more information at
http://www.aps.anl.gov/Accelerator_Syst ... ode52.html and
http://www.aps.anl.gov/Accelerator_Syst ... de134.html

Of course, you'll want more terms than this to avoid crazy beta functions elsewhere. For example
&optimization_term term = "max.betax" &end
&optimization_term term = "max.betay" &end
will ask elegant to minimize the maximum beta functions in both planes.

--Michael