Elegant users forum

Dear Dr.Borland

We are interested in studying the jitter introduced by modification of in the beam line of an FEL set up. In this connection
I was trying to understand the function of the command

&error _element………….&end

This type of commands are used in the example of “ bunchCompJitter”.

My difficulty is the following :

A bunch of 1000 particles is created in this programme using “&bunched_beam……..&end”.
The ‘t (time)’ values associated with the particles are decided by the parameter sigma_s=650e-6.

There is a command used in the programme –

! Incoming timing jitter from injector
&error_element name=MALIN, item=DT, amplitude=1e-13, &end

When I run the programme and see the error Log(.erl) file I get two parameters :

Parameter Value = -1.282581654870911e-014 Parameter Error-1.282581654870911e-014 .

I was expecting change in the ‘t’ values associated with the 1000 particles from bunch 1 (for which there are no errors)
to bunch 2. But there was no change in the ‘t’ values of bunch 1 and bunch 2.

I was trying to understand how the value mentioned in the .erl file is related to the changes in ‘t’ values from bunch 1 to bunch 2.

Regards.

asgekar

You'll see the change in the 't' values only after passing through the beamline, e.g., in a WATCH file or the main output file (from &run_setup).

For an example, see the bunchCompJitter directory in the elegant examples file.

--Michael