| Paper |
Title |
Page |
| MOPC056 |
Challenges for Beams in an ERL Extension to CESR
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190 |
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- G. Hoffstaetter, I. V. Bazarov, S. A. Belomestnykh, M. G. Billing, G. W. Codner, J. A. Crittenden, B. M. Dunham, M. P. Ehrlichman, M. J. Forster, S. Greenwald, V. O. Kostroun, Y. Li, M. Liepe, C. E. Mayes, H. Padamsee, S. B. Peck, D. H. Rice, D. Sagan, Ch. Spethmann, A. Temnykh, M. Tigner, Y. Xie
CLASSE, Ithaca
- D. H. Bilderback, K. Finkelstein, S. M. Gruner
CHESS, Ithaca, New York
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Cornell University is planning to build an Energy-Recovery Linac (ERL) X-ray facility. In this ERL design, a 5 GeV superconducting linear accelerator extends the CESR ring. Currently CESR is used for the Cornell High Energy Synchrotron Source (CHESS). The very small electron-beam emittances would produce an x-ray source that is significantly better than any existing storage-ring light source. However, providing, preserving, and decelerating a beam with such small emittances has many issues. We describe our considerations for challenges such as optics, space charge, dark current, coupler kick, ion accumulation, electron cloud, intra beam scattering, gas scattering, radiation shielding, wake fields including the CSR wake, and beam stabilization.
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| TUPC032 |
Phase Space Tomography Using the Cornell ERL DC Gun
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1119 |
| |
- F. E. Hannon
Jefferson Lab, Newport News, Virginia
- I. V. Bazarov, B. M. Dunham, Y. Li, X. G. Liu
Cornell University, Department of Physics, Ithaca, New York
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The brightness and quality of electron beams in linac-based light sources are ultimately limited by the properties of the beam in the injector. It is thus important to have knowledge of the phase space distribution in addition to the rms emittance to provide an insight into high beam brightness formation mechanisms. A tomography technique has been used to reconstruct the transverse phase space of the electron beam delivered from the Cornell University ERL DC gun. The tomography diagnostic utilised three solenoid magnets directly after the DC gun and a view-screen. The injector was operated at 250keV in the emittance dominated regime, and the results showed good agreement to the phase space measured using a slit-screen method and that generated from simulation with the particle tracking code ASTRA. Comparison of various reconstruction methods is provided.
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| WEPC118 |
Study of Controllable Polarization SASE FEL by a Crossed-planar Undulator
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2282 |
| |
- B. Faatz, Y. Li, J. Pflueger, E. Saldin, E. Schneidmiller, M. V. Yurkov
DESY, Hamburg
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A potential and economical access to generate arbitrary polarized XFEL is to utilize crossed-undulator scheme instead of helical undulators. In this paper, the polarization of x-ray radiation for the European XFEL is investigated. The degree of polarization and the Stokes parameters are calculated for different configurations. The shot-to-shot fluctuation of polarization and the degree of polarization distribution over the transverse plane are also studied.
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| WEPC129 |
Undulator Demagnetization due to Radiation Losses at FLASH
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2308 |
| |
- J. Skupin, B. Faatz, Y. Li, J. Pflueger, T. Vielitz
DESY, Hamburg
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The free-electron laser FLASH was set up at DESY Hamburg in 2004. It is a high-gain, single pass FEL which operates in the VUV and soft X-ray wavelength regime. To monitor the demagnetization of the undulator structures due to radiation losses a small test undulator was installed. This dosimetric undulator (DU) consists of a short piece of magnetic undulator structure with only 3 pole pairs and corresponding magnets. It is positioned in front of the first undulator module where a high dose rate is to be expected. The accumulated dose of DU and undulator system is derived by weekly measurements with thermoluminescence dosimeters (TLDs). The DU is dismounted and magnetically measured regularly. Based on these measurements a (maximal) relative demagnetization rate of about 5*10-4/kGy was derived. In view of this result magnetic measurements on one of the undulators from TTF1 (the predecessor of FLASH) were reviewed. They show a relative demagnetization rate of about 2*10-4/kGy which is lower but still in the same range as the result from FLASH. FEL simulations to analyse the influence of the demagnetization on the SASE process are in progress.
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