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Dear Sir/Madam,

Currently I am working on a 100 MeV, 10A, 10 nsec pulsed RF Linac. I am interested to find out the beam driven monopole and dipole modes that arises inside the cavity of the linac. Here I have attached elegant files for a small section of the linac for your kind reference.

I tried to simulate the above problem in elegant, but the result seems to be wrong.

I may request you to help me to sort out the problem and make necessary corrections in the .ele and .lte files.

Thanking you and waiting for your kind reply.

Ignoring the bunch length, the expected induced voltage is omega*Ra/(4*Q)*charge, or 0.718 MV. If I set sigma_s = 1e-6 (to give a negligible bunch length) in run1.ele, I get just that voltage (look at the column VPostBeam in the .rec file). If the bunch is long (e.g., greater than a few mm), the voltage decreases because the transit time of the bunch is non-negligible compared to the rf period.

--Michael