EPAC08 - Classification:02 Synchrotron Light Sources and FELs/T02 Lepton Sources

02 Synchrotron Light Sources and FELs

T02 Lepton Sources

Paper	Title	Page
MOPC065	Wake Field Simulations for Structures of the PITZ RF Photoinjector: Emittance growth estimations	217
	E. Arevalo, W. Ackermann, E. Gjonaj, W. F.O. Müller, S. Schnepp, T. Weiland TEMF, Darmstadt
	One of the main concerns in the design of electron guns is the generation of low-emittance beams. One source of emittance growth is the beam-surrounding effect, which can be estimated from the wake potentials along the beam path. For the calculation of these potentials an accurate knowledge of the short range wake fields induced in the different parts of the gun with geometrical discontinuities is necessary. The computation of these wake fields is a challenging problem, as an accurate resolution for both the small bunch and the large model geometry is needed. Here with the help of numerical wake-potential calculations we analytically estimate the emittance growth for the RF electron gun of the Photoninjector Test Facility at DESY Zeuthen (PITZ).
MOPC066	Optimisation of a SRF High Average Current SRF Gun	220
	C. D. Beard, J. W. McKenzie, B. L. Militsyn, B. D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
	An approximately 100 mA and 10 MeV continuous wave electron injector is required to deliver high brightness electron bunches for the spontaneous and VUV radiation sources. One of possible solutions might be a Superconductive RF (SRF) gun. Optimisation of the first half cell of the gun has been carried out to maximise the acceleration whilst providing additional focussing through shaping of the cathode region to meet the design specification. In this paper, the cavity design and specification are presented together with some initial optimisations.
MOPC067	Normal Conducting CW RF Gun Design for High Performance Electron Beams	223
	H. Bluem, T. Schultheiss, L. M. Young AES, Medford, NY R. A. Rimmer Jefferson Lab, Newport News, Virginia
	High repetition rate (>1 MHz), high charge (1 nC), low emittance (1 micron) electron beams are an important enabling technology for next generation light sources. Advanced Energy Systems has begun the development of an advanced, continuous-wave, normal-conducting radio frequency electron gun. This gun is designed to minimize thermal stress, allowing fabrication in copper, while providing low emittance electron beams. Beam dynamics performance will be presented along with thermal and stress analysis of the gun cavity design.
MOPC068	Preliminary Characterization of the Beam Properties of the SPARC Photoinjector	226
	A. Cianchi INFN-Roma II, Roma D. Alesini, M. Castellano, E. Chiadroni, L. Cultrera, G. Di Pirro, M. Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, G. Gatti, B. Marchetti, E. Pace, C. Vaccarezza, C. Vicario INFN/LNF, Frascati (Roma) A. Mostacci Rome University La Sapienza, Roma C. Ronsivalle ENEA C. R. Frascati, Frascati (Roma)
	The SPARC photoinjector is the test prototype of the recently approved SPARX project. It is used as R&D facility to perform accurate beam dynamics studies, comparing measurements and simulations. Emittance measurements at the gun exit and at the full energy has been performed and benchmarked with the simulations.
MOPC071	Development of a High Brightness Photo-Injector for Light Source Research at NSRRC	229
	W. K. Lau, J. H. Chen, C. S. Chou, G.-Y. Hsiung, K. T. Hsu, J.-Y. Hwang, A. P. Lee, C. C. Liang, G.-H. Luo, D.-J. Wang NSRRC, Hsinchu C. H. Chen, N. Y. Huang, Y.-C. Huang, W. K. Luo NTHU, Hsinchu
	A laser driven photo-cathode rf gun system is being installed at NSRRC gun testsite for high brightness electron beam and light source research. The photo-cathode rf gun cavity geometry has been modified from the BNL 1.6-cell structure for 2998 MHz operation. A 798 nm Ti:Saphire laser seeded 3 mJ regenerative amplifier is employed to produce 300 microjoules UV pulses at 266 nm wavelength from a third harmonic generator crystal for emission of photo-electrons from the Cu-cathode in the rf gun. First operation of this system with gaussian laser pulses is scheduled in summer 2008. Future plan for flattop laser pulse operation will be discussed.
MOPC072	Photocathode Studies at FLASH	232
	S. Lederer, S. Schreiber DESY, Hamburg J. H. Han Diamond, Oxfordshire P. M. Michelato, L. Monaco, C. Pagani, D. Sertore INFN/LASA, Segrate (MI)
	Since several years, the DESY photoinjectors at FLASH and PITZ use cesium telluride photocathodes. One concern of operating an electron source with these cathodes is the degradation of the quantum efficiency (QE), starting from about 10 % to below 0.5 % during operation. To further understand this behavior the QE is monitored routinely. In this paper recent results from photocathode studies at FLASH are presented.
MOPC073	Design of an Upgrade to the ALICE Photocathode Electron Gun	235
	B. L. Militsyn, B. D. Fell, L. B. Jones, J. W. McKenzie, K. J. Middleman STFC/DL/ASTeC, Daresbury, Warrington, Cheshire I. Burrows, R. J. Cash STFC/DL, Daresbury, Warrington, Cheshire S. N. Kosolobov, H. E. Scheibler, A. S. Terekhov ISP, Novosibirsk
	The design of an upgrade to the GaAs photocathode electron gun of the Energy Recovery Linac Prototype (ERLP) at Daresbury Laboratory is presented. This proposed upgrade includes a reduction of the photocathode diameter from 32 to 10 mm and the installation of a dedicated photocathode preparation system with side loading of the photocathodes. The preparation system forms a united vacuum system with the gun but is separated by a gate valve. This allows for significant improvements to the vacuum conditions in the gun and a reduction of pollution from caesium vapour which improves gun stability under high voltage. This preparation facility will reduce the time taken for photocathode changeover from weeks to hours. The facility should provide photocathodes with higher quantum efficiency due to a more controllable preparation procedure and allows experiments to be performed with photocathodes activated to different levels of electron affinity.
MOPC074	3D Simulations of a Non-axisymmetric High Average Current DC Photocathode Electron Gun	238
	J. W. McKenzie, B. L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
	At high average currents, GaAs photocathode based electron guns are limited by the short operational lifetime of the photocathodes. One method to improve the cathode lifetime is to situate the photocathode off-axis to reduce the flow of ions back-bombarding the emitting surface. The results of 3D electrostatic and beam dynamic simulations are presented to demonstrate the feasibility of this scheme and the resultant beam quality achievable.
MOPC075	Cs2Te Photocathode Robustness Studies	241
	D. Sertore, P. M. Michelato, L. Monaco, C. Pagani INFN/LASA, Segrate (MI) S. Lederer, S. Schreiber DESY, Hamburg F. Stephan DESY Zeuthen, Zeuthen
	Cs2Te photocathodes are used as laser driven electron sources at FLASH and PITZ. Besides many aspects of their performances, their robustness to gas exposition and the effect of pollutants on photocathode properties, and indirectly on the photoemitted electrons, are a field still rather unexplored. In this article we present the results of controlled exposition of Cs2Te photocathodes to gases typical present in the UHV environment of an RF Gun with respect to spectral response (QE vs. wavelength), and QE uniformity. Moreover, a comparison between polluted cathodes and fresh ones during operation in an RF Gun is presented.
MOPC078	Tuning and Conditioning of a New High Gradient Gun Cavity at PITZ	244
	S. Rimjaem, G. Asova, J. W. Baehr, C. H. Boulware, H.-J. Grabosch, M. Hänel, Ye. Ivanisenko, M. Krasilnikov, S. Lederer, A. Oppelt, B. Petrosyan, T. A. Scholz, A. Shapovalov, R. Spesyvtsev, L. Staykov, F. Stephan DESY Zeuthen, Zeuthen K. Floettmann, D. Reschke DESY, Hamburg L. Hakobyan YerPhI, Yerevan R. Richter BESSY GmbH, Berlin J. Roensch Uni HH, Hamburg
	A new 1.3 GHz photo cathode electron gun (prototype 4.2) for the Photo Injector Test facility in Zeuthen (PITZ) was tuned in February 2007. The main difference in the mechanical design compared to earlier guns is a significantly improved cooling system. This gun is also the first copper gun cavity where a particle free cleaning using dry ice technique was applied while in the previous guns the high pressure ultra pure water rinsing technique was used. The cavity has been installed in a new Conditioning Test Stand (CTS) at PITZ in autumn 2007. It has been conditioned to an accelerating gradient of 60 MV/m and more. Dark current measurements have been performed to monitor the improvement of conditioning and to compare with the results from the previous guns. In this paper, RF measurement and tuning results as well as results of the conditioning and dark current measurements will be presented and discussed.
MOPC080	Status of the FERMI@Elettra Photoinjector	247
	M. Trovo, L. Badano, S. Biedron, D. Castronovo, F. Cianciosi, P. Craievich, G. D'Auria, M. B. Danailov, M. Ferianis, S. V. Milton, G. Penco, L. Pivetta, L. Rumiz, D. Wang ELETTRA, Basovizza, Trieste H. Badakov, A. Fukasawa, B. D. O'Shea, J. B. Rosenzweig UCLA, Los Angeles, California M. Eriksson, D. Kumbaro, F. Lindau MAX-lab, Lund
	The new FERMI@Elettra photoinjector is presently undergoing high-power testing and characterization at MAX-Lab in Lund Sweden. This effort is a collaboration between Sincrotrone Trieste, MAX-Lab and UCLA. The 1.6-cell RF gun cavity and the focusing solenoid were successfully designed and built by the Particle Beam Physics Laboratory at UCLA, delivered to Sincrotrone Trieste at the beginning of 2008, and installed in the linac tunnel at MAX-Lab. Use of the MAX-Lab facility will allow the FERMI project to progress significantly with the photoinjector while waiting for the completion of the new linac building extension at Sincrotrone Trieste. We report here on the high-power conditioning of the RF cavity and the first beam tests. Furthermore, a preliminary characterization of the 5 MeV beam will also be presented.