FLS 2006 - List of Keywords (electron)

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

electron

Paper	Title	Other Keywords	Page
PLT04	Design Considerations for Table-Top FELs	undulator, simulation, acceleration, emittance	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.
	Slides

PLT14	Short Radiation Pulses in Storage Rings	radiation, laser, storage-ring, synchrotron	14
	S. Khan Uni HH, Hamburg
	Funding: Funded by the Bundesminister für Bildung und Forschung and by the Land Berlin The time resolution of experiments with synchrotron radiation, presently limited by a typical bunch length of 30–100 ps in electron storage rings, can be improved by making the bunches shorter (e.g. reducing the momentum-compaction factor or increasing the rf gradient) or by establishing a temporal-transverse correlation (e.g. transverse rf deflection or fs-laser slicing). Several methods, their present status and their respective merits or shortcomings are discussed.
	Slides

WG112	Proposal of a Synchrotron Radiation Facility to Supply Ultraviolet Light, X-Ray, MeV-photon, GeV-photon and Neutron	laser, photon, synchrotron, radiation	24
	Y. Kawashima JASRI/SPring-8, Hyogo-ken
	This is a proposal of new facility, which consists of 1 GeV-linac, booster synchrotron and storage ring. The synchrotron accelerates electron beam from 1 GeV to 10 GeV. The storage ring stores the beam at arbitrary energy from 1 GeV to 10 GeV and top-up operation is carried out at any stored beam energy. The stored beam current depends on the beam energy. In the energy region of 8 GeV to 10 GeV, maximum beam current is around 100mA. Under the energy of 4 GeV, the targeted maximum current is 1 A. The storage ring supplies ultraviolet light, MeV-photon, GeV-photon and neutron for solid-state physics, biology, protein structure analysis, drug development and particle physics. The main feature of the facility is to be able to supply the monoenergetic MeV-photon and neutron. With CO₂ laser and stored electron beam, monoenergetic MeV-photons are produced through the inverse Compton process. To obtain the target monoenergetic MeV-photon, the wavelength of the laser is constant; on the other hand stored beam energy is changed. Using a superconducting wiggler, a lot of MeV photons are radiated from the wiggler. With the radiated MeV-photon and beryllium target, neutrons are produced.

WG313	Beam Physics Highlights of the FERMI@ELETTRA Project	linac, emittance, 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.
	Slides

WG322	Status of the SPARX FEL Project	emittance, linac, brightness, 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
	Slides

WG333	High Harmonic Seeding and the 4GLS XUV-FEL	laser, photon, optics, controls	36
	B. Sheehy Sheehy Scientific Consulting, Wading River, New York J. A. Clarke, D. J. Dunning, N. Thompson CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire B. W.J. McNeil USTRAT/SUPA, Glasgow
	The Fourth Generation Light Source (4GLS) project, proposed by the CCLRC in the U. K., will include free electron lasers in the XUV, VUV, and IR. It is proposed that the XUV-FEL, operating between 8–100 eV, be seeded by a high harmonic (HH) source, driven by an ultrafast laser system. This offers advantages in longitudinal coherence, synchronization, and the potential for chirped pulse amplification and pulse shaping. In this talk we discuss the issues of HH generation relevant to its use as a seed (energy, spectrum, tunability, synchronization and time structure) and the current planned implementation in the 4GLS XUV-FEL.
	Slides

WG343	Production of Coherent X-Rays with a Free-Electron Laser Based on Optical Wiggler	laser, radiation, emittance, 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.
	Slides

WG403	Laser System of Photocathode RF Gun in Pohang Accelerator Laboratory	laser, cathode, gun, optics	42
	C. Kim, J. Choi, J. Y. Huang, I. S. Ko, Y. W. Parc, J. H. Park, S. J. Park PAL, Pohang, Kyungbuk
	Funding: Work supported by the Ministry of Science and Technology (MOST), Korea. A photocathode RF gun have been installed in a photo-injector test facility for the PAL XFEL in the Pohang Accelerator Laboratory. The photocathode RF gun will provide electron bunches which have high charge (1 nC), short bunch length (10 ps). For this purpose, a new laser system was installed and it can provide laser pulses of 2 mJ energy, 110 fs pulse width at 800 nm wavelength. A triple harmonic generator and Ultraviolet (UV) stretcher system were added to generate UV laser pulses with controllable pulse widths which can be increased up to 10 ps. In this article, we introduce our laser system and report recent progress of electron beam generations under the various laser conditions.
	Slides

WG422	Proposal of a Photocathode Impulse-Gun and Followed by Impulse Accelerating Structures to Produce Low Emittance Electron Beam	emittance, 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.
	Slides

WG512	Longitudinal Diagnostics with THz Radiation	radiation, diagnostics, linac, synchrotron	48
	H. Delsim-Hashemi, P. Schmüser Uni HH, Hamburg O. Grimm, B. Schmidt DESY, Hamburg
	According to the FEL theory, the longitudinal charge distribution in an electron bunch has an important effect on lasing process. For FLASH at DESY, structures in the order of 10 μm play a crucial role in SASE production. The investigation of the electron bunch longitudinal charge distribution and its bunch to bunch changes is one of the most important issues for optimizing the operation of the machine and improving its stability. Single shot spectroscopic in the 10–200 μm regime is beyond the capability of existing spectroscopic diagnostic tools. This paper introduces a new diagnostics method based on fast spectrally resolved detection of coherent infrared radiation from electron bunches. Measurement results at FLASH with this spectrometer in both scanning mode and single shot mode are presented and discussed.
	Slides

WG517	X-ray Pulse Length Characterization Using the Surface Magneto Optic Kerr Effect	laser, polarization, radiation, photon	51
	P. Krejcik SLAC, Menlo Park, California
	It will be challenging to measure the temporal profile of the hard X-ray SASE beam independently from the electron beam in the LCLS and other 4th generation light sources. A fast interaction mechanism is needed that can be probed by an ultra-fast laser pulse in a pump-probe experiment. It is proposed to exploit the rotation in polarization of light reflected from a thin magnetized film, known as the surface magneto optic Kerr effect (SMOKE), to witness the absorption of the X-ray pulse in the thin film. The change in spin orbit coupling induced by the X-ray pulse occurs on the sub-femtosecond time scale and changes the polarization of the probe beam. The limitation to the technique lies with the bandwidth of the probe laser pulse and how short the optical pulse can be made. The SMOKE mechanism will be described and the choices of materials for use with 1.5 Å X-rays. A schematic description of the pump-probe geometry for X-ray diagnosis is also described.
	Slides