FLS 2006 - List of Keywords (emittance)

A B C D E G I L O P Q R S U V

emittance

Paper	Title	Other Keywords	Page
PLT03	Energy Recovery Linac Experimental Challenges	linac, photon, undulator, optics	7
	D. H. Bilderback Cornell University, Department of Physics, Ithaca, New York
	ERL projects are ongoing at Jlab, Daresbury, KEK and Cornell. Here we describe the typical experimental concerns of using high-coherence and ultra-fast pulses from the Cornell ERL as an example of a new opportunities. The hi-flux mode is one where the ERL runs at 5 GeV and 100 mA. Many experiments are photon-starved, such as inelastic X-ray scattering. The high-coherence mode is obtained at 25 mA and the transverse emittances could be as low as 8 pm. The beam size will be at its smallest under this operating condition and average spectral brightness as high as 10²³ (standard units) are calculated. (WG2 will discuss the ERL accelerator issues.) We expect to produce a 3 micron round emitting source for imaging and coherence experiments on individual biological cells. The ultra-fast mode is one obtained by reducing the repetition rate to 1 MHz and by increasing the bunch charge to 1 nC per pulse and compressing the natural 2 ps bunch length to less than 100 fs. We will present science opportunities for X-ray experiments on a single atom as well as the challenges in optics, other experiments, and beam control issues when making a 1 nm focused X-ray beam size.
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PLT04	Design Considerations for Table-Top FELs	electron, undulator, simulation, acceleration	10
	F. J. Gruener, S. Becker, T. Eichner, D. Habs, U. Schramm, R. Sousa LMU, München M. Geissler, J. Meyer-ter-Vehn MPQ, Garching, Munich S. Reiche UCLA, Los Angeles, California
	Refinements in laser technology (few-cycle pulse generation, chirped pulse amplification) combined with super-computer-based plasma simulations have brought the discipline of relativistic laser-matter interaction to a new level of predictability. This was recently demonstrated by the generation of brilliant electron bunches with energies on the 100-MeV-scale (and supposedly already around 1 GeV). Our plan is to utilize such laser-accelerated electron beams to realize table-top FELs. The essential feature of those electrons is their ultra-high beam current of up to few 100 kA in 10 fs. Such high currents make small-period undulators realistic, which require less electron energy for the same FEL wavelength. Together with low emittance and relatively large Pierce parameter the undulator length for reaching SASE saturation should be as small as only meter-scales. In this paper we present our first basic design considerations based upon start-to-end simulations including 3d PIC codes and GENESIS 1.3. In contrast to the large-scale XFELs, which will be dedicated user facilities, our aim is just to deliver the proof-of-principle of table-top FELs, starting from the VUV to the X-ray range.
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PLT31	Summary of WG1 – Storage Ring Based Radiation Sources	storage-ring, radiation, lattice, photon	18
	K. C. Harkay ANL, Argonne, Illinois A. Ropert ESRF, Grenoble
	Summary of the Storage Ring Based Radiation Sources working group The proposed topics of discussion in the Storage Ring Radiation Sources Working Group are presented. The questions addressed to the participants are the following: What ring parameters may lead to new science? Can we go beyond the present state of the art sources? What critical accelerator technologies require development? Upgrade of existing sources: What is feasible? Is it worth building cost-effective but lower performing rings? Should we build multipurpose or specialised sources?
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WG313	Beam Physics Highlights of the FERMI@ELETTRA Project	linac, electron, simulation, laser	27
	S. Di Mitri, M. Cornacchia, P. Craievich, G. Penco, M. Trovo ELETTRA, Basovizza, Trieste P. Emma, Z. Huang, J. Wu SLAC, Menlo Park, California D. Wang MIT, Middleton, Massachusetts A. Zholents LBNL, Berkeley, California
	The electron beam dynamics in the Fermi Linac has been studied in the framework of the design of a single-pass free electron laser (fel) based on a seeded harmonic cascade. The wakefields of some accelerating sections represent a challenge for the preservation of a small beam emittance and for achieving a small final energy spread. Various analytical techniques and tracking codes have been employed in order to minimize the quadratic and the cubic energy chirps in the longitudinal phase space, since they may cause a degradation of the fel bandwidth. As for the transverse motion, the beam breakup (bbu) instability has been recognized as the main source of emittance dilution; the simulations show the validity of local and non-local correction methods in order to counteract the typical “banana” shape distortion of the beam caused by the instability.
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WG322	Status of the SPARX FEL Project	linac, brightness, electron, simulation	30
	C. Vaccarezza INFN/LNF, Frascati (Roma)
	SPARX is a proposal for a X-ray-FEL facility jointly funded by MIUR (Research Department of Italian Government), Regione Lazio, CNR, ENEA, INFN and Rome University Tor Vergata. It is the natural extension of the ongoing activities of the SPARC collaboration. The aim is the generation of electron beams characterized by ultra-high peak brightness at the energy of 1 and 2 GeV, for the first and the second phase respectively. The beam is expected to drive a single pass FEL experiment in the range of 13.5–6 nm and 6–1.5 nm, at 1 GeV and 2 GeV respectively, both in SASE and SEEDED FEL configurations. A hybrid scheme of RF and magnetic compression will be adopted, based on the expertise achieved at the SPARC [1] high brightness photoinjector presently under installation at Frascati INFN-LNF Laboratories. The use of superconducting and exotic undulator sections will be also exploited. In this paper we discuss the present status of the collaboration. on behalf of the SPARX team
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WG324	Single Bunch Emittance Preservation in XFEL Linac	linac, quadrupole, booster, single-bunch	33
	V. M. Tsakanov, G. A. Amatuni CANDLE, Yerevan R. Brinkmann, W. Decking DESY, Hamburg
	The single bunch emittance preservation in booster and main linacs of European XFEL project is presented. The wakefield and chromatic dilution of the beam emittance caused by free betatron oscillations, cavity and modules offset misalignments and random tilts are evaluated. The effects of cavities misalignments correlation along the linac are discussed. The effects of quadrupole misalignments and the corresponding trajectory steering based on one-to-one correction technique are given. The residual chromatic emittance dilution of the corrected trajectory is evaluated.
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WG343	Production of Coherent X-Rays with a Free-Electron Laser Based on Optical Wiggler	laser, radiation, electron, collective-effects	39
	C. Maroli, V. Petrillo Universita' degli Studi di Milano, Milano A. Bacci INFN/LASA, Segrate (MI) M. Ferrario INFN/LNF, Frascati (Roma) L. Serafini INFN-Milano, Milano
	Funding: Istituto Nazionale di Fisica Nucleare(INFN) - Sezione di milano The interaction between high-brightness electron beams and counter-propagating laser pulses produces X-rays via Thomson scattering. If the laser source is long enough the electrons bunch on the scale of the emitted X-ray wavelength and a regime of collective (coherent) emission can be established. The emitted radiation grows exponentially and the system behaves as a FEL with optical undulator. The bandwidth of the emitted X-rays is sharper than that of the usual incoherent emission. Emittance of the beam and gradients and irregularities of the laser intensity spatial distribution are the principal factors that limit the growth of the X-ray signal. The characters of the emission and the corresponding X-ray spectra are analyzed on the basis of a 3D code. The scalings typical of the optical wiggler with very short gain lengths and short time duration of the ineteraction allow considerable emissions also in violation of criteria valid for static wigglers. The parameters chosen in the cases examined allow a classical treatment of the lasing process.
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WG422	Proposal of a Photocathode Impulse-Gun and Followed by Impulse Accelerating Structures to Produce Low Emittance Electron Beam	electron, space-charge, laser, cathode	45
	Y. Kawashima JASRI/SPring-8, Hyogo-ken
	The photocathode impulse-gun must be one of the best methods to produce low emittance electron beam for FEL. To raise the beam energy up to around 10 MeV, RF cavity will be used. However, there is drift space between the photocathode impulse-gun and RF cavity. The beam emittace will get worse due to space charge effect in passing through the drift space. Thus the drift space should be as shorter as possible. Minimizing the space charge effect is essential for the early stage of beam acceleration at an electron beam source and a following pre-acceleration. Mechanically unavoidable drift space degrades the beam emittance drastically. We propose a combined structure of a photocathode impulse-gun followed by an impulse accelerator.
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