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Bisognano, J.

Paper Title Page
TUPMS041 The Wisconsin VUV/Soft X-ray Free Electron Laser Project 1278
  • J. Bisognano, R. A. Bosch, M. A. Green, H. Hoechst, K. Jacobs, K. J. Kleman, R. A. Legg, R. Reininger, R. Wehlitz
    UW-Madison/SRC, Madison, Wisconsin
  • J. Chen, W. Graves, F. X. Kaertner, J. Kim, D. E. Moncton
    MIT, Cambridge, Massachusetts
  Funding: Work supported by the University of Wisconsin - Madison. SRC is supported by the U. S. National Science Foundation under Award No. DMR-0537588.

The University of Wisconsin-Madison and its partners are developing a design for an FEL operating in the UV to soft x-ray range that will be proposed as a new multidisciplinary user facility. Key features of this facility include seeded, fully coherent output with tunable photon energy and polarization over the range 5 eV to 1240 eV, and simultaneous, independent operation of multiple beamlines. The different beamlines will support a wide range of science from femto-chemistry requiring ultrashort pulses with kHz repetition rates to photoemission and spectroscopy requiring high average flux and narrow bandwidth at MHz rates. The facility will take advantage of the flexibility, stability, and high average pulse rates available from a CW superconducting linac driven by a photoinjector. This unique facility is expected to enable new science through ultra-high resolution in the time and frequency domains, as well as coherent imaging and nano-fabrication. This project is being developed through collaboration between the UW Synchrotron Radiation Center and MIT. We present an overview of the facility, including the motivating science, and its laser, accelerator, and experimental systems.

TUPMS042 A Superconducting Linac Driver for the Wisconsin Free Electron Laser 1281
  • J. Bisognano, R. A. Bosch, M. A. Green, K. Jacobs, K. J. Kleman, R. A. Legg
    UW-Madison/SRC, Madison, Wisconsin
  • J. Chen, W. Graves, F. X. Kaertner, J. Kim
    MIT, Cambridge, Massachusetts
  Funding: Work supported by the University of Wisconsin - Madison. SRC is supported by the U. S. National Science Foundation under Award No. DMR-0537588.

We present an initial design of the driver for the Wisconsin VUV/Soft Xray FEL facility, which will provide high intensity coherent photons from 5 eV to 1.2 keV. It uses a 2.5 GeV, L-band CW superconducting linac with a 1.7 GeV tap-off to feed the lower energy FELs. In order to support multiple high rep-rate FELs, the average design current is 1 mA. Sub-nanocoulomb bunches with normalized transverse emittances of order 1 micron are generated in a photoinjector for beamlines operating at repetition rates from kHz to MHz. Multi-stage bunch compression provides 1 kA peak current to the FELs, with low energy spread and a suitable current profile. Compressed bunch lengths of several hundred femtoseconds will allow generation of photon pulses in the range 10 to 100 fs using cascaded FELs. Consideration has been given to removing the residual energy chirp from the beam, and minimizing the effects of space charge, coherent synchrotron radiation, and microbunching instabilities. A beam switchyard using RF separators and fast kickers delivers the desired electron bunches to each of the FELs. Details of the design will be presented, including those areas requiring the most development work.

TUPMS044 Design of a 980 MeV Energy Recovery Linac 1287
  • R. A. Bosch, J. Bisognano, M. D. Medley
    UW-Madison/SRC, Madison, Wisconsin
  Funding: This research was supported by National Science Foundation grant no. DMR-0537588.

A 980-MeV energy recovery linac with radiofrequency (rf) of 1.5 GHz is designed. Electrons are accelerated by two passages through a 480-MeV superconducting linac, and decelerated by two subsequent passages. Recirculation is accomplished with six 60-degree bending magnets. The threshold current for beam breakup instability exceeds 100 mA. Gaussian bunches with normalized transverse emittances of 0.1 mm-mrad and rms length of 1.85 ps may be compressed by a factor of 180 (to a bunch length of 10 fs) with only a slight increase in transverse normalized emittance. Bunch charges up to 8 pC may be compressed at 980 MeV without excessive degradation from coherent synchrotron radiation, allowing operation with beam currents up to 12 mA.

TUPMS045 Improvements to the Aladdin Synchrotron Light Source 1290
  • K. Jacobs, J. Bisognano, R. A. Bosch, D. Eisert, M. V. Fisher, M. A. Green, R. G. Keil, K. J. Kleman, R. A. Legg, G. C. Rogers, J. P. Stott
    UW-Madison/SRC, Madison, Wisconsin
  Funding: Work supported by the U. S. National Science Foundation under Award No. DMR-0537588.

Aladdin is an IR to soft x-ray synchrotron light source operated by the University of Wisconsin at Madison. As part of the ongoing program of upgrades and improvements, several changes have recently been made to the ring. It had previously been determined that physical apertures (BPMs) at the QF quadrupoles were limiting beam lifetime when the ring was operated in its low emittance configuration. Increasing the size of these apertures has resulted in a significant increase in lifetime. Also as part of the aperture opening process, a number of ring components were redesigned and replaced, lowering the ring impedance. This has led to an increase in the threshold beam current for microwave instability. Another modification was the design and installation of discrete trim coils on the quadrupole pole-tips to facilitate using the quads as steering correctors. Details of these and other improvements will be presented.