LINAC 2004 - List of Keywords

A B C D E F G H I K L M O P Q R S T U V

undulator

Paper	Title	Other Keywords	Page
MO102	Accelerator Layout of the XFEL	linac, electron, site, photon	2
	R. Brinkmann DESY, Hamburg
	The X-ray Free Electron Laser XFEL is a 4th generation synchrotron radiation facility based on the SASE FEL concept and the superconducting TESLA technology for the linear accelerator. In February 2003 the German government decided that the XFEL should be realized as a European project and located at DESY/Hamburg. The Ministry for Research and Eduation also announced that Germany is prepared to cover half of the investment and personnel costs of the project. This paper gives an overview of the overall layout and parameters of the facility, with emphasis on the accelerator design, technology and physics.
	Transparencies

MOP25	The LEBRA 125 MeV Electron Linac for FEL And PXR Generation	electron, linac, klystron, laser	90
	K. Hayakawa, Y. Hayakawa, K. Ishiwata, K. Kanno, K. Nakao, T. Sakai, I. Sato, T. Tanaka LEBRA, Funabashi K. Yokoyama KEK, Ibaraki
	A 125 MeV electron linac has been constructed at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University for Free Electron Laser (FEL) and Parametric X-ray (PXR) generation. Two klystrons feed rf power of approximately 20 MW peak and 20 μsec pulse duration each to an injector and three 4 m accelerating structures. Phase of the rf fed to each component is controlled independently. Two accelerating structures connected with the second klystron and a ninety degrees bending system as a momentum analyzer constitute a magnetic bunching system. Electron bunches of 3 to 4 psec width formed at the injector are compressed to within 1 psec during passing through the magnetic bunching system. Peak current of the electron beam injected to the FEL system installed downstream of the momentum analyzer is expected to be about 50 A. FEL lasing has been achieved at the wavelength range from 1 to 6 mm. Estimated peak power of the extracted FEL light pulse is about 2 MW. Applied researches using the FEL started last autumn. Preliminary experiment for the PXR generation has been continued.

MOP38	Background from Undulator in the Proposed Experiment with Polarized Positrons	electron, background, photon, positron	123
	Y.K. Batygin SLAC, Stanford
	E-166 is a proposed experiment for verification of polarized positron production for linear collider. According to polarized positron source design, high energy electrons pass through helical undulator and produce circularly polarized photons, which interact with tungsten target and produce longitudinally polarized positrons. In the proposed E-166 experiment, 50 GeV beam propagates inside 1m long undulator followed by a drift space of 35 m before interaction with target. Polarized positrons are analyzed by Si-W calorimeter, which is placed along the axis. Polarized positrons are analyzed by CsI calorimeter after reconversion of positrons to photons at the second target. Background is an issue for a considered experiment. GEANT3 simulations were performed to model production of secondary particles from primary electrons hitting undulator. Energy density distribution of background particles at the target and effect of background collimation are discussed.

MOP68	Ribbon Ion Beam Dynamics in Undulator Linear Accelerator	focusing, acceleration, ion, linac	177
	E.S. Masunov, S.M. Polozov MEPhI, Moscow
	The possibility to use radio frequency undulator fields for ion beam focusing and acceleration in linac (UNDULAC-RF) is discussed. In periodical resonator structure the accelerating force is produced by the combination of two or more space harmonics of a longitudinal or a transverse undulator field. The particle motion equations in Hamilton form are carried out by means of smooth approximation. The analysis of 3D effective potential permits to find the conditions under which focusing and acceleration of the particles occur simultaneously. The analytical results are verified with a numerical simulation. Examples illustrating the efficiency of the proposed method of acceleration are given for longitudinal and transverse undulators. The results are compared with a conventional linac and the other possibility of ion beam acceleration in UNDULAC-E(M) where electrostatic and magnetic fields are used. E.S. Masunov, Technical Physics, Vol. 46, No.11, 2001, pp. 1433-1436.

TU102	Survey of Advanced Acceleration Techniques	electron, laser, plasma, acceleration	242
	C.J. Joshi UCLA, Los Angeles, California
	In this talk I will review the recent progress on the production, manipulation, transport, acceleration and focusing of relativistic electron beams using advanced techniques. In particular, I will report recent progress on cathode-less electron injectors, IFEL bunchers and accelerators, plasma accelerating and transport structures, and electron and positron beam focusing using plasmas. The plasma structures for acceleration can be excited either by laser beams or charged-particle beams. The acceleration gradients in either case can be enormous. For unmatched beams the betatron radiation loss, as the beam oscillates transversely in the high gradient accelerating structure, can generate a high brightness x-ray beam. These x-rays can, in turn, be used to generate positrons. Work done by different groups around the world will be reviewed.
	Transparencies

TUP42	Beam Optics Studies for the TESLA Test Facility Linac	optics, focusing, linac, quadrupole	360
	P. Castro, V. Balandin, N. Golubeva DESY, Hamburg
	The aim of the TESLA Test Facility Linac is to create electron bunches of small transverse emittance and high peak current with energies up to 1 GeV for the VUV-FEL at DESY. The linac consists of a RF photo-cathode gun, a superconducting linac, two magnetic chicanes (for bunch compression), a long undulator magnet section and a beam line bypassing the undulator (for commissioning purposes). A study of (linear) beam optics of the linac is presented for the case of beam commissioning (and beam measurements), FEL operation and long bunch train operation. The requirements of each part of the linac upon the optics are discussed in detail and an appropriate solution for each case is shown, as well as the matching solution to the rest of the accelerator. The chromatic properties of the linac have been studied also.

TUP45	Extended Parametric Evaluation for 1 Å FEL - Emittance and Current Requirements	emittance, electron, radiation, gun	369
	M. Pedrozzi, G. Ingold PSI, Villigen
	In the synchrotron radiation community there is a strong request for high brightness, coherent X-ray light pulses, especially in the 1 to 0.1 nm wave length range. A Free Electron Laser (FEL), driven by a linear single pass accelerator, is today the most promising mechanism able to produce such radiation. Since the electron beam brightness plays a major role in the laser saturation process and in the final energy of the driving linac, many laboratories are presently working on a new generation of low emittances sources. The present analysis will give an indication about the FEL behaviour and the undulator parameters versus the slice beam quality (emittance, current, energy spread).

TUP53	Temporal Profile of the LCLS Photocathode Ultraviolet Drive Laser Tolerated by the Microbunching Instability	simulation, laser, damping, emittance	390
	J. Wu, Z. Huang SLAC, Menlo Park, California M. Borland ANL, Argonne, Illinois P. Emma SLAC/ARDA, Menlo Park, California C. Limborg SLAC/SSRL, Menlo Park, California
	The high quality LCLS electron beam generated in the photoinjector is subject to all possible instabilities in the downstream acceleration and compression. The instability can be initiated by any possible density modulation of the electron beam when it is generated at the photocathode. In this note, we prescribe the tolerance on the initial electron beam density modulation possibly introduced by the ultraviolet (uv) laser at the cathode. Our study shows that the initial rms density modulation of the electron beam at the photocathode shall be less than 5 % to ensure the FEL lasing and saturation.

TUP64	Bunch Length Measurements at LEBRA	electron, linac, klystron, simulation	411
	K. Yokoyama KEK, Ibaraki K. Hayakawa, Y. Hayakawa, K. Nakao, I. Sato, T. Tanaka LEBRA, Funabashi
	The bunch length of the electron beam from the FEL linac at LEBRA (Laboratory for Electron Beam Research and Application) was estimated from the phase ellipse coefficient which is deduced from the dependence of the beam spread on the accelerating phase. The bunch length of FWHM was estimated approximately 0.33 mm from the results of the experiments. Besides, the pulse length of the FEL lights around the wavelength of 1.5 μm was measured by means of the autocorrelation. The pulse length was less than 0.06 mm according to the number of interfacial waves. These results indicate that the pulse length of the FEL lights isn’t equivalent to the electron bunch length.

TUP72	TTF II Beam Monitors for Beam Position, Bunch Charge and Phase Measurements	vacuum, pick-up, instrumentation, single-bunch	435
	M. Wendt, D. Nölle DESY, Hamburg
	An overview of the basic beam instrumentation with regard to elecromagnetic beam monitors for the TESLA Test Facility phase II (TTF II) is given. Emphasis is put on beam position monitor (BPM) and toroid transformer systems for beam orbit and bunch charge observations. Furthermore broadband monitors, i.e. wall current and bunch phase monitors, are briefly presented.

WE204	PAL Linac Upgrade for a 1-3 Å XFEL	linac, emittance, radiation, electron	544
	J-O. Oh, W. Namkung POSTECH, Pohang Y. Kim DESY, Hamburg
	With the successful SASE FEL saturation at 80 nm wavelength at TTF1, TTF2 will begin re-commissioning in the fall of 2004 as an FEL user facility to 6 nm with 1 GeV beams. The high gain harmonic generation is also confirmed by the DUV-FEL experiments at 266 nm with seeding wavelength at 800 nm. In order to realize a hard X-ray SASE FEL (SASE XFEL) with a lower energy beams, we need a long in-vacuum mini-gap undulator and a GeV-scale FEL driving linac that can supply an extremely low slice emittance, a high peak current, and an extremely low slice energy spread. PAL is operating a 2.5 GeV electron linac as a full-energy injector to the PLS storage ring. By adding an RF photo-cathode gun, two bunch compressors, and a 0.5 GeV S-band injector linac to the existing PLS linac, and by installing a 60 m long in-vacuum undulator, the PLS linac can be converted to a SASE XFEL facility (PAL XFEL) which supplies coherent X-ray down to 0.3 nm wavelength. The third harmonic enhancement technique can supply coherent hard X-ray beams to 0.1 nm. The technical parameters related to these goals are examined, and preliminary design details are reviewed for the PAL linac upgrade idea for a 1-3 Å PAL XFEL.
	Transparencies

THP22	3D Beam Dynamics Simulation in Undulator Linac	simulation, ion, linac, bunching	642
	E.S. Masunov, S.M. Polozov MEPhI, Moscow
	The ion beam can be bunched and accelerated in linear accelerator with RF undulator (UNDULAC-RF). The acceleration and focusing of beam can be realized without using a synchronous wave. In this paper the computer simulation of high intensity ion beam dynamics in UNDULAC-RF was carried out by means of the "superparticles" method. The computer simulation and optimization of ion dynamics consist of two steps. At the first, the equations of particles motion in polyharmonic fields are devised by means of smooth approximation. Hamiltonian analysis of these equations allows to find a velocity of reference particle in polyharmonic field and to formulate the conditions of good longitudinal bunching and transverse focusing beam. At the second, the 3D ion beam dynamics simulation in an UNDULAC is governed by founded functions of reference particle velocity and a ratio of amplitude harmonics. The influence of the space charge on RF focusing conditions, transmission coefficient, longitudinal and transverse emittances, and other acceleration system characteristics are investigated by computer simulation. Masunov E.S., Sov. Phys.-Tech. Phys., vol. 35, No. 8, p. 962, 1990.