| Paper |
Title |
Other Keywords |
Page |
| MOP82 |
SRF Cavity and Materials R&D at Fermilab
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superconductivity, vacuum, electron, emittance |
213 |
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- N. Khabiboulline, P. Bauer, L. Bellantoni, T. Berenc, C. Boffo, R. Carcagno, C. Chapman, H. Edwards, L. Elementi, M. Foley, E. Hahn, D. Hicks, D. Mitchell, A. Rowe, N. Solyak, I. Terechkine
FNAL, Batavia, Illinois
- A. Gurevich, M. Jewell, D. C. Larbalestier, P. Lee, A. Polyanskii, A. Squitieri
UW-Madison/ASC, Madison, Wisconsin
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Two 3.9 GHz superconducting RF cavities are under development at FNAL for use in the upgraded Photoinjector Facility. A TM110 mode cavity will provide streak capability for bunch slice diagnostics, and a TM010 mode cavity will provide linearization of the accelerating gradient before compression for better emittance. The status of these two efforts and a review of the FNAL infrastructure development will be given.
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| TUP76 |
Adaptive Feedforward Cancellation of Sinusoidal Disturbances in Superconducting RF Cavities
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damping, feedback, simulation, linac |
447 |
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- T.H. Kandil, T.L. Grimm, W. Hartung, H. Khalil, J. Popielarski, J. Vincent, R.C. York
NSCL, East Lansing, Michigan
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A control method, known as adaptive feedforward cancellation (AFC) is applied to damp sinusoidal disturbances due to microphonics in superconducting RF (SRF) cavities. AFC provides a method for damping internal, and external sinusoidal disturbances with known frequencies. It is preferred over other schemes because it uses rudimentary information about the frequency response at the disturbance frequencies, without the necessity of knowing an analytic model (transfer function) of the system. It estimates the magnitude and phase of the sinusoidal disturbance inputs and generates a control signal to cancel their effect. AFC, along with a frequency estimation process, is shown to be very successful in the cancellation of sinusoidal signals from different sources. The results of this research may significantly reduce the power requirements and increase the stability for lightly loaded continuous-wave SRF systems.
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| THP92 |
Effect of the Tuner on the Field Flatness of SNS Superconducting RF Cavities
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simulation, coupling, resonance, pick-up |
815 |
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- A. Sun
ORNL/SNS, Oak Ridge, Tennessee
- H. Wang, G. Wu
Jefferson Lab, Newport News, Virginia
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Field flatness in a multi-cell superconducting cavity affects not only the net accelerating voltage, but also the peak surface field and the Lorenz Force detuning coefficient. Our measurement indicates that the field flatness changes both external Q of the Fundamental Power Coupler (FPC) and external Q of the Field Probe (FP). The field amplitude tilts linearly to the distance between the cell center and the cavity’s geometry center (pivot point). The tilt rate has been measured in a cryomodule cold (2 K) test, being about 2%/100 kHz, relative the field flatness at the cavity’s center frequency of 805 MHz. Bead-pull measurements confirmed that the field flatness change is 2.0%/100 kHz for a medium β cavity with helium vessel, and 1.72%/100 kHz without helium vessel. These results matched the predictions of simulations using ANSYS and SUPERFISH. A detailed analysis reveals that longitudinal capacitive gap deformation is the main cause of the frequency change. Field flatness change was not only due to the uneven stored energy change within the cell, but also due to cell-to-cell coupling.
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