CSR induced energy spread
Posted: 05 Dec 2019, 14:38
Dear all,
Hello, I am currently studying the CSR induced energy spread and the emittance growth.
Following the references (PRST-AB 4, 070701, PRST-AB 17, 060701, etc ...), rms energy spread induced by CSR can be calculated
by the equation (related to the beam charge, dipole length and bending radius, energy, and bunch length).
Using the equation, when the beam charge is 100 pC, bunch length of 60 um, energy of 165 MeV, arclength of 0.1 m, and bending angle of 10 deg,
the rms energy spread induced by the CSR is about 8.2135E-5.
However, when I ran the simulation using real beam distribution, and using the ideal beam generated from ELEGANT,
the CSR induced energy spread is totally different. In this case I obtained this energy spread from 'Sdelta_B1 - Sdelta_i'
where Sdelta_B1 is the energy spread after passing through the dipole magnet, and Sdelta_i is the initial energy spread.
- Concerning this issue, I have some questions.
1. I was wondering if the energy spread induced only by CSR can be estimated by above approach (Sdelta_B1 - Sdelta_i).
If it is not, how can I estimate only the CSR induced energy spread from the ELEGANT results?
2. In the case of ideal beam (also longitudinal Gaussian distribution), energy spread after dipole magnet is extremely small.
I would like to know why the energy spread is really small, and to know how to estimate this small value (if there is some analytic formula?)
3. On the other hand, real beam case I can see some increases of the energy spread, but it is still smaller than the value from equation.
I also check the longitudinal histogram, but it is somewhat similar to the Gaussian distribution.
Does this longitudinal distribution (phase space) play a role of the CSR induced energy spread?
Please find attached files for the .ele and .lte file for the details.
Thank you for your help in advance...!
Hello, I am currently studying the CSR induced energy spread and the emittance growth.
Following the references (PRST-AB 4, 070701, PRST-AB 17, 060701, etc ...), rms energy spread induced by CSR can be calculated
by the equation (related to the beam charge, dipole length and bending radius, energy, and bunch length).
Using the equation, when the beam charge is 100 pC, bunch length of 60 um, energy of 165 MeV, arclength of 0.1 m, and bending angle of 10 deg,
the rms energy spread induced by the CSR is about 8.2135E-5.
However, when I ran the simulation using real beam distribution, and using the ideal beam generated from ELEGANT,
the CSR induced energy spread is totally different. In this case I obtained this energy spread from 'Sdelta_B1 - Sdelta_i'
where Sdelta_B1 is the energy spread after passing through the dipole magnet, and Sdelta_i is the initial energy spread.
- Concerning this issue, I have some questions.
1. I was wondering if the energy spread induced only by CSR can be estimated by above approach (Sdelta_B1 - Sdelta_i).
If it is not, how can I estimate only the CSR induced energy spread from the ELEGANT results?
2. In the case of ideal beam (also longitudinal Gaussian distribution), energy spread after dipole magnet is extremely small.
I would like to know why the energy spread is really small, and to know how to estimate this small value (if there is some analytic formula?)
3. On the other hand, real beam case I can see some increases of the energy spread, but it is still smaller than the value from equation.
I also check the longitudinal histogram, but it is somewhat similar to the Gaussian distribution.
Does this longitudinal distribution (phase space) play a role of the CSR induced energy spread?
Please find attached files for the .ele and .lte file for the details.
Thank you for your help in advance...!