Edwards H.

Paper	Title	Page
TU204	Review of SRF Materials Workshop	94
	G. Wu, L. Cooley, H. Edwards Fermilab C. Antoine CEA-Saclay
	The performance of niobium cavities has approached the theoretical hard limit. Yet the consistent achievement of higher performing cavities remains the greatest challenge. To further understand the basic materials science, a workshop was held at Fermilab in May 2007 to present and discuss the fundamental and experimental limitations, and propose new ideas.
	Slides(PDF)
TUP49	ECR Plasma Cleaning: An In-situ Processing Technique for RF Cavities	243
	G. Wu, H. Jiang, T. Khabiboulline, I. Pechenezhskiy, T. Koeth, J. Reid, W. Muranyi, B. Tennis, E. Harms, Y. Terechkine, H. Edwards, D. Mitchell, A. Rowe, C. Boffo, C. Cooper, L. Cooley, R. Schuessler Fermilab W. -D. Moeller DESY Hamburg C. Antoine CEA-Saclay A. Romanenko Cornell University
	A condition for Electron Cyclotron Resonance (ECR) can be established inside a fully assembled RF cavity without the need for removing high-power couplers. As such, plasma generated by this process can be used as a final cleaning step, or as an alternative cleaning step in place of other techniques. We will describe the current effort to study plasma cleaning by ECR in a 3.9GHz cavity.
TUP57	First Fermilab Results of SRF Cavity Lorentz Force Detuning Compensation Using a Piezo Tuner	259
	R. Carcagno, J. Branlard, B. Chase, H. Edwards, D. Orris, Y. Pischalnikov, A. Makulski, J. Reid, W. Schappert Fermilab
	Lorentz force detuning compensation of TESLA type cavities using commercially available piezo electric actuators was first demonstrated at DESY [1]. Compensating for Lorentz force detuning to avoid excessive RF power requirements is critical for high gradient cavities such as the ones proposed for the ILC. For this reason, Fermilab is working on issues related to range, reliability, and automation of SRF cavity fast tuners. A mechanical resonance excitation method is used to increase the piezo tuner range. In order to study the long-term reliability of the design a strain-gauge based sensor was developed, which monitors the piezo tuner preload continuously. A feed forward Lorentz force detuning compensation algorithm using the forward power signal, the field probe signal, and the phase difference between them has been developed. This algorithm is being implemented in a hybrid PC/FPGA based control system providing automated signal acquisition, system identification, and waveform playback. In parallel, an FPGA based real-time cavity simulator has been developed to validate the performance of the system prior to its deployment and to provide a testbed for further detuning and microphonics algorithm development. The control system will be used to compensate for cavity detuning in the first cryomodule installed in the ILC Test Area at Fermilab. In tests of the algorithm using CCII at a gradient of 26 MV/m, compensation with a fast piezo tuner reduced the Lorentz Force detuning from 275 Hz to 20 Hz. This compensation resulted in a corresponding decrease of the peak klystron power requirement from 120% to 105% of the nominal power on resonance.
WEP17	Considerations on the third harmonic RF of the European XFEL	481
	E. Vogel, M. Dohlus, M. Huening, K. Jensch, A. Matheisen, W. -D. Moeller, A. Schmidt, W. Singer DESY Hamburg H. Edwards, E. Harms, T. Khabiboulline Fermilab
	Ultra short bunches with high peak current are required for the creation of high brilliance coherent light in the x-ray range in undulators. At the European x-ray free electron laser (XFEL) they will be obtained by a two stage bunch compression scheme based on off the rf field crest acceleration and transverse magnetic chicanes. The deviation of the rf field's sine shape from a straight line leads to long bunch tails and reduce peak current. This effect will be eliminated by adding a third harmonic rf system. The paper surveys the basic principle for the third harmonic rf, the most relevant design parameters, the actual status of beam physical examinations and potential concepts for the technical realization.
WEP41	Status of 3.9 GHz superconducting RF cavity technology at Fermilab	575
	E. Harms, T. Arkan, L. Bellantoni, H. Carter, H. Edwards, M. Foley, I. Gonin, T. Khabiboulline, D. Mitchell, D. Olis, A. Rowe, N. Solyak Fermilab
	Fermilab is involved in an effort to assemble 3.9 GHz superconducting RF cavities into a four cavity cryomodule for use at the DESY TTF/FLASH facility as a third harmonic structure. The design gradient of the cavities is 14 MV/m. This effort involves design, fabrication, intermediate testing, assembly, and eventual delivery of the cryomodule. We report on all facets of this enterprise from design through future plans. Included will be test results of single 9-cell cavities, lessons learned, and current status.