Elegant users forum

Posted: **16 Jan 2019, 10:34**

Dear all,

My name is Sukho. I'm new to Elegant. I tried to track a beam and get the data from all BPMs.
I added
&alter_elements name=*, type=CSBEND, item=SYNCH_RAD, value=1 &end
&alter_elements name=*, type=CSBEND, item=ISR, value=1 &end
to the .ele file. I also added misalignment to one of the Quadrupoles. After some time passed, it should give us the COD. However, after I track the particle for about 1 second, the particle seems to oscillate larger and larger.

: w1.png (7.77 KiB) Viewed 4250 times

(I choose the initial position close to the COD at s=0.)

Then I tried to remove RF from both the .lte and remove &rf_setup from the .ele file, but the particle lost after about 1 ms.

Could you please help me?

Best Regards,
Sukho

Posted: **22 Jan 2019, 11:42**

Sukho,

I think the problem is your rf_setup command

Code: Select all

&rf_setup ! remove RF from RING
        harmonic=1320,
        bucket_half_height=1,
        over_voltage=1,
&end

First, the over_voltage setting is ignored in favor of the bucket_half_height. However, a bucket half height of 1 (i.e., +/-100%) isn't meaningful and results in a huge rf voltage (2.3 GV). With such a huge voltage, the potential for large energy swings is high. Try setting the bucket_half_height to a smaller value, e.g., 0.05.

--Michael

Posted: **22 Jan 2019, 16:08**

Thank you, Michael. I'll try it.

Best Regards,
Sukho

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Tracking with damping, amplitude is getting larger

Tracking with damping, amplitude is getting larger

Re: Tracking with damping, amplitude is getting larger

Re: Tracking with damping, amplitude is getting larger