In the chart section it is possible to plot the r/Q calculated for each cavity.
For some cavities, the value seems to not be correct.
If I understand correctly, r/Q is calculated with :
r/Q = Vc^2 /(ω U )
- Vc: is the calculated accelerating voltage (plot ‘voltage per cavity’).
- U is the stored energy that has to be defined by the user in ‘Section or Family -> reflected power’;
Generally the user will define the value of the stored energy according to the targeted Eacc: defined in ‘Max. Eacc’ in Section -> cavity’. But some cavities, especially at the beginning of an accelerating section, operate at a lower field. Consequently the calculated r/Q for these cavities is not correct.
A proposed solution to correct r/Q calculation without ’breaking’ the rest of the code could be :
- Specify to the user that the stored energy has to be defined for the targeted Eaccref (at βref = βopt or βg depending on the chosen definition of Eacc) : defined in ‘Max. Eacc’ in Section -> cavity’.
This will enable to calculate r/Qref :
r/Qref = (Eaccref. Lacc)^2 /(ω U) - Then as r/Q depends on β, the calculation for cavity #ii is :
r/Q_ii = r/Qref * (Eacc(β_ii)/Eaccref)^2
with Eacc(β_ii)= E0 * TTF(β_ii) & E0 = Eaccref/TTF(βref)
Would it be possible to correct the calculation of r/Q in Genlinwin?
Cheers
fred
