Elegant users forum

Hi,

I would like to simulate the influence on beam from the generator current (Ig) noise, together with the rf-feedbacks.
Is there any example showing how to set the generator current noise in rf mode element?

yours Chao

Chao,

You can find something very similar to what you need in the examples file, under storageRingRfNoise.

--Michael

Dear Michael,
Thanks for your quick reply.

What I am trying to simulate is the rf-noise and rf-feedbacks in the mode element.
The purpose is to know if the feedback can follow the rf-noise and maintain the cavity voltage.

In the simulation, the filling pattern is set as 3840=80*(1bunch+47gap), which is uniformly filled by 80 bunches.

I have a preliminary one-trun rf-feedback, which is represented by the inPhase- and outPhase- feedback filters.
Since it is one-turn feedback, there are 81 rows. Meanwhile, there is a noise file, represented by rfNoise_harm.sdds.
Inside this file, I specified the voltage and phase errors, in a very ideal sinusoid noise.


I am using the filles in this way:

RFMODE3FB: RFMODE, RS=36.0e6, Q=17000, beta=5.0, bin_size=1e-12, n_bins=1000, FREQ="f0 ringHarm * 3 * detune_fre3 +", DRIVE_FREQUENCY="f0 ringHarm * 3 * ", &
V_SETPOINT="V_Hc", PHASE_SETPOINT="Phi_Hc", PRELOAD=1,PRELOAD_HARMONIC="ringHarm 3 *", bunched_beam_mode=1, LONG_RANGE_ONLY=1, &
sample_interval=1,flush_interval=100, &
IN_PHASE_FILTER="InPhase_FeedbackFilters.sdds", QUADRATURE_FILTER="OutPhase_FeedbackFilters.sdds",update_interval=3840,feedback_record="%s.rfhc-fb", &
NOISE_ALPHA_V="rfNoise_harm3.sdds=time+volError", NOISE_PHI_V="rfNoise_harm3.sdds=time+phiError"

In simulation, I set the beam current as zero. When I look into the IgAmplitude data, specified by the "feedback_record", it gives me
result as shown. Could you please help me to set the simulation up appropriately ?

yours Chao

Chao,

It's a bit hard to comment without having all the files, but have you tried a simple bandpass filter for the feedback filters? That should suppress the modulation you are imposing in the noise input.

--Michael