Tracking a beam coming from linac in to booster

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arahim
Posts: 26
Joined: 08 Jun 2012, 05:28

Tracking a beam coming from linac in to booster

Post by arahim » 30 Jun 2020, 07:31

I have generated a linac output bunch (single) by the command &bunched_beam.
&bunched_beam
n_particles_per_bunch = 20000,
emit_x = 60e-09,
sigma_dp = 0.005,
sigma_s = 0.15,
emit_y = 60e-09,
beta_x = 15.83,
alpha_x=2.6589,
beta_y = 5.45,
alpha_y=-0.9191,
eta_x = 0.27655,
etap_x=-0.0468,
enforce_rms_values[0] = 3*1,
&end

I am tracking this beam in the booster at injection energy. Booster emittance, energy spread and bunch length is compratively smaller as compared to linac output beam. After tracking the emittance, energy spread and bunch length should converge to the booster natural values but they increase. Files are attached for the reference.

Arahim
Attachments
run2.ele
(332 Bytes) Downloaded 223 times
Booster_single_bunch_linac.out
(1016.73 KiB) Downloaded 159 times
Booster_insta_lattice.lte
(1.09 KiB) Downloaded 218 times

michael_borland
Posts: 1801
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
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Re: Tracking a beam coming from linac in to booster

Post by michael_borland » 30 Jun 2020, 13:18

Arahim,

I think it is just a matter of your damping time being extremely long (probably seconds) at 200 MeV. You only tracked for 3000 turns.

--Michael

michael_borland
Posts: 1801
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
Contact:

Re: Tracking a beam coming from linac in to booster

Post by michael_borland » 30 Jun 2020, 15:03

Arahim,

I found a few other problems
  • You were not computing the rf frequency accurately enough. This causes momentum offsets that can change the damping rate significantly. I added statements to address this.
  • Your initial beam is spread over several buckets, so there are particles outside the bucket that rattle around and confuse the statistics. I added a CLEAN element to remove these particles.
  • You need to track many more turns as the damping time is several seconds.
Please see attached.

--Michael
Attachments
2020-06-30a.zip
(961.86 KiB) Downloaded 243 times

arahim
Posts: 26
Joined: 08 Jun 2012, 05:28

Re: Tracking a beam coming from linac in to booster

Post by arahim » 06 Jul 2020, 00:02

Thanks..I had tracked up to 10 Lakh turns. Correcting the RF frequency and clean command actually worked well.. Thank you vey much..

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