Publications
Publication Information
| Title | Analysis and Management of Microphonics in Operational SRF Cavities With Bandwidths of approximately 10 Hz |
| Authors | Thomas Powers |
| JLAB number | JLAB-ACO-17-2614 |
| LANL number | (None) |
| Other number | DOE/OR/23177-6398 |
| Document Type(s) | (Meeting) |
| Associated with EIC: | No |
| Supported by Jefferson Lab LDRD Funding: | No |
| Funding Source: | Nuclear Physics (NP) |
|
Meeting Abstract compiled for SRF 2017 (18th International Conference on RF Superconductivity) | |
| Publication Abstract: | Superconducting Radio Frequency Cavity detuning can be due to several effects. These effects include helium pressure variations, vibrations driven by external narrow band sources such as HVAC motors, cooling water systems, tuner motor operation, cryogenic system machinery, and occasionally cryogenic system instabilities such as thermo-acoustic oscillations. They can also be driven by broadband white or pink noise which, in general, will excite the resonant modes of the structure. All of these affect the cavity resonant frequency. Variations that occur at frequencies above a few tenths of a Hertz are considered microphonics. CEBAF 0.7 m C100 cavities operated at 1500 MHz with 20 Hz bandwidths, changes in cavity lengths on the order of 10 nm are sufficient to shift the cavity frequency by more than one bandwidth. Jefferson Lab is the first lab to install and operate a large number of SRF cavities with relatively high loaded-Qs, 88 in CEBAF and 16 in the LERF (previously the FEL). Production was halted for several months after the first 3 production C100 cryomodules were built, and modifications were developed in order to reduce the background microphonics. Additionally, in the spring of 2016 we started a program to harden and damp the cryomodule interface structures in order to reduce the sensitivity to outside perturbations as well as to damp out the natural vibrational modes of the structures. This work will focus on the approaches and measurements that one should consider when designing a system in order to understand the modal nature of the structure, the measurement techniques for determining the extent of the microphonics, and the mitigations that can be implemented in order to reduce the effects of outside perturbances. Examples of results at various other institutions will also be presented. |
| Experiment Numbers: | other |
| Group: | Operations Support |
| Document: | docx |
| DOI: | |
| Accepted Manuscript: | frxba04_talk.pdf |
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