Kneisel, P.

Paper	Title	Page
MOPCH182	The JLAB Ampere-class Cryomodule Conceptual Design	490
	R.A. Rimmer, G. Ciovati, E. Daly, T. Elliott, J. Henry, W.R. Hicks, P. Kneisel, S. Manning, R. Manus, J.P. Preble, K. Smith, M. Stirbet, L. Turlington, L. Vogel, H. Wang, K. Wilson, G. Wu Jefferson Lab, Newport News, Virginia
	For the next generation of compact high-power FELs a new cryomodule is required that is capable of accelerating up to Ampere levels of beam current. Challenges include strong HOM damping, high HOM power and high fundamental-mode power (in operating scenarios without full energy recovery). For efficient use of space a high real-estate gradient is desirable and for economic operation good fundamental-mode efficiency is important. The technology must also be robust and should be based on well-proven and reliable technologies. For Ampere-class levels of beam current both halo interception and beam break-up (BBU) are important considerations. These factors tend to drive the designs to lower frequencies where the apertures are larger and the transverse impedances are lower. To achieve these goals we propose to use a compact waveguide-damped multi-cell cavity packaged in an SNS-style cryomodule.
WEXPA01	Latest Developments in Superconducting RF Structures for Beta=1 Particle Acceleration	1837
	P. Kneisel Jefferson Lab, Newport News, Virginia
	Superconducting RF technology is since nearly a decade routinely applied to different kinds of accelerating devices: linear accelerators, storage rings, synchrotron light sources and FEL's. With the technology recommendation for the International Linear Collider (ILC) a year ago, new emphasis has been placed on improving the performance of accelerating cavities both in Q-value and in accelerating gradients with the goal to achieve performance levels close to the fundamental limits given by the material parameters of the choice material, niobium. This paper will summarize the challenges to SRF technology and will review the latest developments in superconducting structure design. Additionally, it will give an overview of the newest results and will report on the developments in alternative materials and technologies.
	Transparencies
THPLS092	Nb-Pb Superconducting RF-Gun	3493
	J.S. Sekutowicz, J.I. Iversen, D. Klinke, D. Kostin, W.-D. Möller DESY, Hamburg I. Ben-Zvi, A. Burrill, T. Rao, J. Smedley BNL, Upton, Long Island, New York M. Ferrario INFN/LNF, Frascati (Roma) P. Kneisel Jefferson Lab, Newport News, Virginia K. Ko, L. Xiao SLAC, Menlo Park, California J. Langner, P. Strzyzewski The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock R.S. Lefferts, A.R. Lipski SBUNSL, Stony Brook, New York J.B. Rosenzweig UCLA, Los Angeles, California K. Szalowski University of Lodz, Lodz
	We report on the status of an electron RF-gun made of two superconductors: niobium and lead. The presented design combines the advantages of the RF performance of bulk niobium superconducting cavities and the reasonably high quantum efficiency of lead, as compared to other superconducting metals. The concept, mentioned in a previous paper, follows the attractive approach of all niobium superconducting RF-gun as it has been proposed by the BNL group. Measured values of quantum efficiency for lead at various photon energies, analysis of recombination time of photon-broken Cooper pairs for lead and niobium, and preliminary cold test results are discussed in this paper.