### the usage of RFMODE element

Posted:

**30 Aug 2017, 06:23**Hi Michael,

It's Haisheng Xu. I'm trying to use elegant to simulate the longitudinal coupled-bunch instability driven by the HOMs of RF cavity.

I try to use the RFMODE element to represent the HOM of RF cavity in the following way:

RFM1 : RFMODE, FREQ=700.88e6, Q=1.4e5, Rs=3.25e6, bin_size=1e-12, n_bins=2000, N_CAVITIES=1, BUNCHED_BEAM_MODE=1, RECORD="%s,rfmm", SAMPLE_INTERVAL=100, PRELOAD=1, LONG_RANGE_ONLY=1

However, I'm puzzling on the settings of this element in one of the elegant examples: .../examples/multibunchCollectiveEffects/APS-24Bunch-CBI/lattice.lte. In this example lattice file, two RFMODE elements are used without initializing the FREQ parameter of both the elements. Would you like to help me understand this setting? What's the resonant frequency of the HOM in this case? Is RFMODE the correct element to simulate the HOMs of RF cavity?

Thanks!

Regards,

Haisheng

It's Haisheng Xu. I'm trying to use elegant to simulate the longitudinal coupled-bunch instability driven by the HOMs of RF cavity.

I try to use the RFMODE element to represent the HOM of RF cavity in the following way:

RFM1 : RFMODE, FREQ=700.88e6, Q=1.4e5, Rs=3.25e6, bin_size=1e-12, n_bins=2000, N_CAVITIES=1, BUNCHED_BEAM_MODE=1, RECORD="%s,rfmm", SAMPLE_INTERVAL=100, PRELOAD=1, LONG_RANGE_ONLY=1

However, I'm puzzling on the settings of this element in one of the elegant examples: .../examples/multibunchCollectiveEffects/APS-24Bunch-CBI/lattice.lte. In this example lattice file, two RFMODE elements are used without initializing the FREQ parameter of both the elements. Would you like to help me understand this setting? What's the resonant frequency of the HOM in this case? Is RFMODE the correct element to simulate the HOMs of RF cavity?

Thanks!

Regards,

Haisheng