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Marhauser, F.

Paper Title Page
WEPMS063 Preliminary Results from Prototype Niobium Cavities for the JLab Ampere-Class FEL 2487
 
  • P. Kneisel, R. Bundy, G. Ciovati, W. Clemens, D. Forehand, B. Golden, S. Manning, R. Manus, R. B. Overton, R. A. Rimmer, G. Slack, L. Turlington, H. Wang
    Jefferson Lab, Newport News, Virginia
  • F. Marhauser
    JLAB, Newport News, Virginia
 
  Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U. S. DOE Contract No. DE-AC05-06OR23177, and by the office of Naval Research under contract to the Department of Energy.

In a previous paper the cavity* design for an Ampere-class cryomodule was introduced. We have since fabricated a 1500 MHz version of a single cell cavity with waveguide couplers for HOM and fundamental power, attached to one end of the cavity, a 5-cell cavity made from large grain niobium without couplers and a complete 5-cell cavity from polycrystalline niobium featuring waveguide couplers on both ends. A 750 MHz single cell cavity without endgroups has also been manufactured to get some information about obtainable Q-values, gradients and multipacting behavior at lower frequency. This contribution reports on the various tests of these cavities.

* R. A.Rimmer et al.; EPAC 2006, paper MOPCH182

 
WEPMS070 Simulation and Measurements of a Heavily HOM-Damped Multi-cell SRF Cavity Prototype 2496
 
  • H. Wang, R. A. Rimmer
    Jefferson Lab, Newport News, Virginia
  • F. Marhauser
    JLAB, Newport News, Virginia
 
  Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U. S. DOE Contract No. DE-AC05-06OR23177, and by The Office of Naval Research under contract to the Dept. of Energy.

After initial cavity shape optimization* and cryomodule development** for an Ampere-class FEL, we have simulated the whole 5-cell high-current (HC) cavity structure with six waveguide couplers for HOM damping and fundamental power coupling. The time-domain wakefield method using MAFIA is primarily used for calculation of the broadband impedance. Microwave Studio and Omega-3P are also used for the calculation of external Q (Qext) of individual HOMs. A half scale (1497MHz) single-cell model and a 5-cell copper cavity including dummy HOM waveguide loads were fabricated. Details of measurement results on these prototypes including HOM Qext spectrum, bead-pull data, data analysis technique and comparison to the simulations will be presented.

* H. Wang et. al., "Elliptical Cavity Shape Optimization for Acceleration and HOM Damping," Proc. PAC 05, Knoxville TN, USA, 2005* R. A.Rimmer et al.; EPAC 2006, paper MOPCH182

 
TUPMN012 STARS - A Two-Stage High-Gain Harmonic Generation FEL Demonstrator 938
 
  • T. Kamps, M. Abo-Bakr, W. Anders, J. Bahrdt, P. Budz, K. B. Buerkmann-Gehrlein, O. Dressler, H. A. Duerr, V. Duerr, W. Eberhardt, S. Eisebitt, J. Feikes, R. Follath, A. Gaupp, R. Goergen, K. Goldammer, S. C. Hessler, K. Holldack, E. Jaeschke, S. Klauke, J. Knobloch, O. Kugeler, B. C. Kuske, P. Kuske, A. Meseck, R. Mitzner, R. Mueller, M. Neeb, A. Neumann, K. Ott, D. Pfluckhahn, T. Quast, M. Scheer, Th. Schroeter, M. Schuster, F. Senf, G. Wuestefeld
    BESSY GmbH, Berlin
  • D. Kramer
    GSI, Darmstadt
  • F. Marhauser
    JLAB, Newport News, Virginia
 
  Funding: Bundesministerium fur Bildung und Forschung and the Land Berlin

BESSY is proposing a demonstration facility, called STARS, for a two-stage high-gain harmonic generation free electron laser (HGHG FEL). STARS is planned for lasing in the wavelength range 40 to 70 nm, requiring a beam energy of 325 MeV. The facility consists of a normal conducting gun, three superconducting TESLA-type acceleration modules modified for CW operation, a single stage bunch compressor and finally a two-stage HGHG cascaded FEL. This paper describes the faciliy layout and the rationale behind the operation parameters.

 
WEPMS068 JLab High-Current CW Cryomodules for ERL and FEL Applications 2493
 
  • R. A. Rimmer, R. Bundy, G. Cheng, G. Ciovati, E. Daly, R. Getz, J. Henry, W. R. Hicks, P. Kneisel, S. Manning, R. Manus, K. Smith, M. Stirbet, L. Turlington, L. Vogel, H. Wang, K. Wilson
    Jefferson Lab, Newport News, Virginia
  • F. Marhauser
    JLAB, Newport News, Virginia
 
  Funding: Authored by Jefferson Science Associates, LLC under U. S. DOE Contract No. DE-AC05-06OR23177, and by The Office of Naval Research under contract to the Dept. of Energy.

We describe the developments underway at JLab to develop new CW cryomodules capable of transporting up to Ampere-levels of beam currents for use in ERLs and FELs. Goals include an efficient cell shape, high packing factor for efficient real-estate gradient and very strong HOM damping to push BBU thresholds up by two or more orders of magnitude compared to existing designs. Cavity shape, HOM damping and ancillary components are optimized for this application. Designs are being developed for low-frequency (750 MHz), Ampere-class compact FELs and for high-frequency (1.5 GHz), 100 mA configurations. These designs and concepts can easily be scaled to other frequencies. We present the results of conceptual design studies, simulations and prototype measurements. These modules are being developed for the next generation ERL based high power FELs but may be useful for other applications such as high energy light sources, electron cooling, electron-ion colliders, industrial processing etc.