Beam Driven Monopole and Dipole modes

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radhakanta
Posts: 4
Joined: 28 Aug 2014, 15:17

Beam Driven Monopole and Dipole modes

Post by radhakanta » 27 Mar 2015, 00:53

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.
Attachments
run2.ele
(268 Bytes) Downloaded 189 times
run1.ele
(533 Bytes) Downloaded 195 times
lattice.lte
(288 Bytes) Downloaded 205 times

michael_borland
Posts: 1959
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
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Re: Beam Driven Monopole and Dipole modes

Post by michael_borland » 01 Apr 2015, 08:50

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

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