IBS and bunch lengthening due to impedance

[Skamarokha]

Hello

I've been trying to setup ibsEmittance and haissinski codes to find beam parameters with consideration of combined effects of IBS and impedance. I see that it has been done before, but I need some advice.

In paper it's said that ibsEmittance code is used to abtain energy spread to use it in Haissinski solver. The latter solves for the bunch length using the wakefield. Iterating between the two codes converges to the solution.

1. I begin iteration with ibsEmittance.

Code: Select all

ibsEmittance $twi_file $ibs_file -charge=$charge -emitInput=$ex0 -deltaInput=$sigma_e -coupling=$ratio -length=$sigma_s -noWarning

2. I put new energy spread in twi file for Haissinski solver to use

Code: Select all

sddsprocess $twi_file_new -redefine=parameter,Sdelta0,$sigma_e -noWarnings

3. Run solver to find new beam length. twi file has energy spread from IBS and I'm assigning length from ibs solver.

Code: Select all

haissinski $twi_file_new $pwd_file -model=Zn=$Zn,R=$R -bunchCurrent=$I -outputLastStepOnly \
 -length=$sigma_t -integrationParameters=deltaTime=$deltaTime,points=4000,iterations=1000,fraction=0.01,tolerance=1e-4

For the next iteration I put in ibsEmittance new total emittance, energy spread and length from previous iteration step. But there is no convergence.

Will it be correct to put RF parameters in haissinski code instead of length with ibs?
What am I missing?

[michael_borland]

Mikhail,

Please see the attached example. It converges in four iterations.

--Michael

[Skamarokha]

Thank you!