IBS effect
Posted: 27 Sep 2021, 08:11
Hi everybody,
I have a question regarding with calculation of IBS effects. I used the “ibsEmittance” command to quickly evaluate impact of IBS on the main beam parameters. I assumed 3 nC bunch charge, 1.42MV RF voltage and set the coupling to 3.356% just to have 8 pm vertical emittance including IBS effect, please see below;
ibsEmittance DTBA.twi DTBA.ibs -charge=3.0 -coupling=0.03356 -RF=Voltage=1.42,harmonic=934 -integrate=turns=30000,stepSize=10
To confirm the results provided by “ibsEmittance” command, the "IBSCATTER" element with 10 longitudinal slices has been inserted in the ring definition and a bunch of 5000 particles with Gaussian distribution has been tracked through the ring for 30000 turns. I have also included SREFFECT in the tracking,
RAD : SREFFECTS, QEXCITATION=1, PREF=6849.327668039155, JX=1.872, JY=1, JDELTA=1.128, EXREF= 1.616545e-10, SDELTAREF= 9.35513e-04, DDELTAREF=-2.06705e-04, INCLUDE_OFFSETS=1,coupling=0.0495
As you see above, I have specified all the parameters in the RAD definition and set coupling to 4.95% which provides 8 pm vertical emittance. This coupling has been used in bunch generation but I didn't use it (4.95% coupling) in ibsEmittance method because if I do, final emittance with ibsEmittance will be much higher than 8 pm. Below are the results which compare tracking with ibsEmittance method;
Final parameters provided by ibsEmittance method are close to tracking results but agreement between the methods as a function of turn is not very good. Do you have any idea for improvement of the results?
Many thanks in advance
Regards
Hossein
I have a question regarding with calculation of IBS effects. I used the “ibsEmittance” command to quickly evaluate impact of IBS on the main beam parameters. I assumed 3 nC bunch charge, 1.42MV RF voltage and set the coupling to 3.356% just to have 8 pm vertical emittance including IBS effect, please see below;
ibsEmittance DTBA.twi DTBA.ibs -charge=3.0 -coupling=0.03356 -RF=Voltage=1.42,harmonic=934 -integrate=turns=30000,stepSize=10
To confirm the results provided by “ibsEmittance” command, the "IBSCATTER" element with 10 longitudinal slices has been inserted in the ring definition and a bunch of 5000 particles with Gaussian distribution has been tracked through the ring for 30000 turns. I have also included SREFFECT in the tracking,
RAD : SREFFECTS, QEXCITATION=1, PREF=6849.327668039155, JX=1.872, JY=1, JDELTA=1.128, EXREF= 1.616545e-10, SDELTAREF= 9.35513e-04, DDELTAREF=-2.06705e-04, INCLUDE_OFFSETS=1,coupling=0.0495
As you see above, I have specified all the parameters in the RAD definition and set coupling to 4.95% which provides 8 pm vertical emittance. This coupling has been used in bunch generation but I didn't use it (4.95% coupling) in ibsEmittance method because if I do, final emittance with ibsEmittance will be much higher than 8 pm. Below are the results which compare tracking with ibsEmittance method;
Final parameters provided by ibsEmittance method are close to tracking results but agreement between the methods as a function of turn is not very good. Do you have any idea for improvement of the results?
Many thanks in advance
Regards
Hossein