EPAC08 - List of Keywords (cathode)

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cathode

Paper	Title	Other Keywords	Page
MOZBM01	High Intensity and Low Emittance Guns	gun, electron, laser, emittance	46
	P. M. Michelato INFN/LASA, Segrate (MI)
	High intensity or high-brilliance, low emittance electron beams are needed for many applications, ranging from SASE FELs to fast radiolysis systems, from Compton backscattering X ray sources to energy recovery linac, from CW FELs to the linear collider. They are produced using a high field RF accelerating structure together with a photoemissive electron source: the rapid acceleration process minimizes the space charge effects which tend to spoil the emitted beam characteristics. The talk will review the technology and provide the important parameters of these sources as the generated bunch charge, the repetition rate, the mean and peak current, the beam emittance, etc, together with an analysis of gun reliability and technological challenges. I will present the state of the art of the technology of the RF guns, either using metallic or semiconductor photoemitters. New high repetition rate/CW sources, appearing in the last years, using superconducting cavities, will be also reviewed.
	Slides

MOPC004	First Results from the Upgraded PITZ Facility	gun, laser, diagnostics, electron	70
	J. W. Baehr, S. Lederer DESY, Hamburg G. Asova INRNE, Sofia C. H. Boulware, H.-J. Grabosch, M. Hänel, Ye. Ivanisenko, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, B. Petrosyan, S. Rimjaem, T. A. Scholz, R. Spesyvtsev, L. Staykov, F. Stephan DESY Zeuthen, Zeuthen L. Hakobyan YerPhI, Yerevan R. Richter BESSY GmbH, Berlin J. Roensch Uni HH, Hamburg K. Rosbach Humboldt University Berlin, Institut für Physik, Berlin A. Shapovalov MEPhI, Moscow
	During autumn and winter 2007 a general reconstruction of the PITZ facility was performed. A new spectrometer based on a dipole magnet with 180 degree deflection angle was inserted in the facility. The new spectrometer contains two screen stations for the measuring of the longitudinal phase space and the slice emittance. A new "Conditioning Test Stand" (CTS) was added to the facility. Using this CTS a new electron gun having an improved cooling system is under conditioning. A new photocathode laser system (developed by MBI) was installed and commissioned. The goal is to reach rise and fall times of the laser pulses of 2 ps. The system of laser diagnostic was upgraded. The results reached using this upgraded facility are reported. This concerns the conditioning results of the new gun. Furthermore, a gun will be characterised using the new diagnostics beamline and the new photocathode laser. Results of the commissioning and first measurements of the new diagnostics components will be reported.

MOPC031	Status of X-ray FEL/SPring-8 Machine Construction	undulator, electron, emittance, gun	136
	T. Shintake RIKEN/SPring-8, Hyogo
	XFEL/SPring-8: the X-ray Free Electron Laser Project is under construction at SPring-8 site, which is aiming at generating 0.1 nm coherent radiation using 8 GeV electron beam. After the ground breaking in 2007, concrete piling has been completed. Construction of the accelerator tunnel will be completed in end of the FY2008, then machine installation will be started. The first electron beam acceleration is scheduled in FY2010. XFEL/SPring-8 based on SASE-FEL, and unique design, thermionic CeB6 gun, adiabatic bunching, C-band high gradient accelerator and in vacuum undulator. To reach 8 GeV within 400 m available tunnel length, we use 64 C-band klystron, which drives 128 accelerating tube at 37 MV/m.

MOPC036	Pancakes versus Beer-cans in Terms of 6D Phase-space Density	laser, emittance, simulation, electron	151
	S. B. van der Geer, O. J. Luiten, M. J. de Loos TUE, Eindhoven S. B. van der Geer Pulsar Physics, Eindhoven
	Uniformly filled ellipsoidal (waterbag) electron bunches can be created in practice by space charge blow out of transversely tailored ‘pancake’ bunches. Ellipsoidal bunches have linear self fields in all dimensions, and will not deteriorate in quality under linear transport and acceleration. There is a discussion if such a bunch is better than a conventional beer-can shape. This paper compares the two approaches in terms of usable phase-space density. Detailed GPT simulations of a simplified setup show that although the pancakes approach requires less charge, it is the application that is decisive. O. J. Luiten et al. Phys. Rev. Lett. Vol 93, 094802 (2004).

MOPC045	First Measurement Results of the PSI 500kV Low Emittance Electron Source	laser, emittance, electron, optics	169
	M. Pedrozzi, Å. Andersson, R. J. Bakker, R. Ganter, C. Gough, C. P. Hauri, R. Ischebeck, S. Ivkovic, Y. Kim, F. Le Pimpec, K. B. Li, P. Ming, A. Oppelt, M. Paraliev, T. Schietinger, V. Schlott, B. Steffen, A. F. Wrulich PSI, Villigen S. C. Leemann MAX-lab, Lund
	The Paul Scherrer Insitute (PSI) is presently developing a low emittance electron source for the PSI-XFEL project. The target beam parameters at the source are I=5.5 A, Q=0.2 nC and a slice emittance below 0.2 mm.mrad. The gun concept consists of a high gradient "diode“ stage followed by a two-frequency two-cell cavity to allow fine tuning of the longitudinal phase space. This paper reports on the first experimental results obtained with the PSI 500 kV test stand. The facility consists of a 500 kV diode stage followed by a diagnostic beam line including an emittance monitor. An air-core transformer based high voltage pulser is capable of delivering a pulse of 250 ns FWHM with amplitude up to 500 kV. The diode gap between two mirror polished electrodes is adjustable to allow systematic gradient studies. The electrons are produced by a 266nm UV laser delivering 4μJoules on the Cu-cathode.

MOPC058	ALICE (ERLP) Injector Design	booster, emittance, gun, laser	196
	B. D. Muratori, Y. M. Saveliev STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
	In this paper we look at how the ALICE (formerly ERLP) injector has been re-designed to meet more realistic criteria from the previous design. A key component of ALICE is the high brightness injector. The ALICE injector consists of a DC photocathode gun generating 80 pC electron bunches at 350 keV. These bunches are then matched into a booster cavity which accelerates them to an energy of 8.35 MeV. In order to do this, two solenoids and a single-cell buncher cavity are used, together with off-crest injection into the first booster cavity, where the beam is still far from being relativistic. The performance of the injector has been studied using the particle tracking code ASTRA.

MOPC066	Optimisation of a SRF High Average Current SRF Gun	gun, emittance, laser, acceleration	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	gun, emittance, simulation, electron	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	emittance, quadrupole, linac, gun	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.

MOPC072	Photocathode Studies at FLASH	vacuum, laser, photon, electron	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	electron, gun, vacuum, laser	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	gun, electron, simulation, ion	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	gun, vacuum, ion, emittance	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	gun, electron, emittance, controls	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.

MOPC098	LHC Particle Collimation by Hollow Electron Beams	electron, collimation, proton, ion	292
	V. D. Shiltsev, A. I. Drozhdin, V. Kamerdzhiev, G. F. Kuznetsov, L. G. Vorobiev Fermilab, Batavia, Illinois
	Electron Lenses built and installed in Tevatron have proven themselves as safe and very reliable instruments which can be effectively used in hadron collider operation for a number of applications, including compensation of beam- beam effects, DC beam removal from abort gaps, as a diagnostic tool. In this presentation we consider a possibility of using electron lenses with hollow electron beam for ion and proton collimation in LHC.

MOPC155	Transport System for Ion Implantation	ion, ion-source, undulator, beam-transport	439
	S. M. Polozov, E. S. Masunov MEPhI, Moscow R. P. Kuibeda, T. Kulevoy, V. Pershin, S. Petrenko, D. N. Selesnev, I. M. Shamailov, A. L. Sitnikov ITEP, Moscow
	ITEP in collaboration with MEPHI and IHE (Tomsk) develops the high intensity ion beam generation and transport systems for low energy (1-50 keV) ion implantation. Such facilities are used for semiconductor technology. The Bernas type ion source is used for ribbon ion beam production. The periodical system of electrostatic lenses (electrostatical undulator) was proposed for ribbon beam transport line. The design of transport system and the results of beam dynamics investigation are presented. The influence of the electrodes construction errors on the beam dynamics is discussed.

MOPD012	Half Wave Injector Design for WiFEL	emittance, gun, space-charge, linac	469
	R. A. Legg UW-Madison/SRC, Madison, Wisconsin W. Graves MIT, Cambridge, Massachusetts T. L. Grimm Niowave, Inc., Lansing, Michigan P. Piot Fermilab, Batavia, Illinois
	Seeded FELs will require exceptional beam quality. The Wisconsin FEL (WiFEL) requires peak currents of greater than 1 kA with less than 1 mm-mrad transverse slice emittance and 1·10^-4 δp/p at the undulator. To perform the obligatory bunch compression after the injector without allowing micro-bunching will require very smooth bunch energy and density profiles and relatively low compression ratios. An injector which uses a low frequency, superconducting, half wave resonator gun combined with self-inflating, ellipsoidal bunches* to meet those requirements is described. The superconducting radio frequency TEM-class cavities have been in use for more than 25 years and because of their potential for flat field profiles, are desirable as electron gun structures. A Superfish model and field map of the specific gun cavity is presented. ASTRA** simulations from the cathode to 120MeV are provided. A description is given of the technique used to emittance compensate the space charge induced energy chirp while maintaining the peak bunch current. * O. J.Luiten, et al., Phys. Rev. Lett. Vol 93, 094802 (2004) ** K. Floetmann, ASTRA, www.desy.de/~mpyflo

MOPD022	New 1MW 704MHz RF Test Stand at CEA-Saclay	klystron, linac, proton, cryogenics	490
	S. Chel, M. Desmons, A. Hamdi, F. Peauger CEA, Gif-sur-Yvette
	In the frame of the european CARE/HIPPI programme, superconducting accelerating cavities for pulsed proton injectors are developed. Qualification of these 704 MHz RF structures fully equipped (housed in a helium tank, with tuning system and power coupler), requires to perform high power tests in the existing horizontal cryostat CryHoLab. During the last years, CEA-Saclay built and ordered the necessary RF equipments to make such a platform for high power RF tests in a cryogenic environment available to the partners in HIPPI and later on to any other interested European teams. The main components of the RF test stand (95 kV-275kVA DC High Voltage Power Supply, 50Hz modulator and 1MW 704.4MHz RF klystron amplifier) are now installed and tested. In this paper, we present the different components with a focus on the new design of the hard tube modulator to match the new specifications and the compatibility with the floating HVPS, the results of the HV and RF measurements performed and we give a brief description of the PXI-based controller for the interlocks and klystron auxiliary controls.

MOPD025	Status of the 805-MHz Pulsed Klystrons for the Spallation Neutron Source	klystron, gun, factory, electron	499
	S. Lenci, E. L. Eisen CPI, Palo Alto, California M. P. McCarthy ORNL, Oak Ridge, Tennessee
	Communications and Power Industries, Inc (CPI) produced 81 klystrons for the Spallation Neutron Source at Oak Ridge National Laboratory. The klystrons are rated for 550 kW peak at 805 MHz. Seventy units have accumulated 1.2M hours of filament operation and 820K hours of high voltage operation through January 2008. A higher power 700 kW version has been developed and is now in production with 12 of the 38 units on order delivered through January 2008. Performance specifications, computer model predictions, operating results, production statistics, and operational status will be presented.

MOPD028	Radio Frequency Power Sources for the Muon Ionisation Cooling Experiment	power-supply, vacuum, controls, monitoring	508
	J. F. Orrett, P. A. Corlett, A. J. Moss, J. H.P. Rogers STFC/DL/ASTeC, Daresbury, Warrington, Cheshire C. J. White STFC/DL, Daresbury, Warrington, Cheshire
	For any future Neutrino Factory the accelerator aperture will be a major cost driver. Potentially the aperture can be reduced and significant capital savings made if ionisation cooling is utilised on the muon beam. In order to demonstrate the effectiveness of ionisation cooling a demonstrator needs to be built and operated. MICE, the Muon Ionisation Cooling Experiment is that demonstrator. The RF requirements of MICE will be met using high power vacuum tube based RF circuits donated by LBNL and CERN. This paper will discuss these circuits, their refurbishment, the construction of HT power supplies and ancillary equipment and high power testing.

MOPD042	Design and Testing of the Horizontal Version of the Multi Beam Klystron for European XFEL Project	klystron, electron, gun, linac	544
	Y. Yano, M. Y. Miyake, Y. Okubo, S. Sakamoto Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi Y. H. Chin KEK, Ibaraki K. Hayashi, K. Tetsuka, H. Urakata TETD, Otawara
	Toshiba Electron Tubes & Devices (TETD) has been developing 10-MW L-band Multi-Beam Klystrons (MBKs) for the European XFEL project and possibly for future linear colliders. In order to allow horizontal installation in the XFEL tunnel, the horizontal version of MBK, MBK E3736H, has been designed, fabricated and tested by TETD. The MBK has six low-perveance beams operated at low voltage of less than 120 kV (for 10MW) and six ring-shaped cavities. In the successful acceptance testing at TETD in August 2007, the MBK achieved an output power of 10.3 MW at the beam voltage of 117 kV and at the RF pulse width of 1.5ms with efficiency of 67%. This test demonstrated that MBK E3736H fulfills all the requirements necessary as the RF power source of the XFEL linac.

MOPP012	DC Breakdown Experiments for CLIC	collider, linear-collider, RF-structure, vacuum	577
	A. Descoeudres, S. Calatroni, M. Taborelli CERN, Geneva
	For the production of the Compact Linear Collider (CLIC) RF structures, a material capable of sustaining high electric field, with a low breakdown rate and showing low damages after breakdowns is needed. A DC breakdown study is underway at CERN in order to test candidate materials and surface preparations, and also to have a better understanding of the breakdown mechanism. The saturated breakdown fields of several metals and alloys have been measured, ranging from 100MV/m for Al to 900MV/m for stainless steel, being around 150MV/m for Cu, CuZr and Glidcop, 300MV/m for W, 400MV/m for Mo, Nb and Cr, 650MV/m for V, and 750MV/m for Ti for example. Titanium shows a strong material displacement after breakdowns, while Cu, Mo and stainless steel are more stable. The conditioning speed of Mo can be significantly improved by removing oxides at the surface with a heat treatment, typically at 875°C for 2 hours. DC breakdown rate measurements have been done with Cu and Mo electrodes, showing similar results as in RF experiments: the breakdown probability seems to exponentially increase with the applied field.

MOPP074	Improvement of an S-band RF-gun cavity with a Cs-Te Photo-cathode	electron, impedance, scattering, resonance	721
	A. Murata, Y. Hama, T. Hirose, Y. Kato, K. Sakaue, T. Suzuki, M. Washio RISE, Tokyo H. Hayano, N. Kudoh, T. T. Takatomi, N. Terunuma, J. Urakawa KEK, Ibaraki Y. Kamiya University of Tokyo, Tokyo S. Kashiwagi ISIR, Osaka M. Kuriki Hiroshima University, Graduate School of Science, Higashi-Hiroshima R. Kuroda AIST, Tsukuba, Ibaraki
	A 1.6cell S-band photo-cathode RF-Gun is one of the good alternatives of the short pulse electron source. Therefore,we are operating as a high brightness short pulse electron source for studying a reaction of radiation chemistry,an inverse Compton scattering at Waseda University and as an injector at KEK-ATF. To improve an electron beam quality and to reduce a dark current,we decided to improve the RF-Gun cavity. Frequency tuning of the half cell of existing RF-gun was performed by the torque control of Helicoflex seal on the cathode plate and two moving rod type tuners were installed on the full cell. Newly designed RF-Gun cavity has four compact tuners on each cell,which can be tune the frequency to deform the cavity wall,to remove the Helicoflex seal and tuning holes that were considered to be the major cause of electric discharge and/or a dark current source. According to these improvements,the Q-value and shunt impedance of the cavity is 30% larger than that of existing guns. As the result,the reduction of dark current is succeeded and the beam energy is reached up to 5.5MeV at 10MW RF input. The detailed results of electron beam generation will be reported at the conference.

MOPP075	Experimental Generation and Characterization of Uniformly Filled Ellipsoidal Electron Beam Distributions	laser, electron, space-charge, emittance	724
	P. Musumeci, J. Moody, J. B. Rosenzweig, C. M. Scoby UCLA, Los Angeles, California
	For forty years, uniformly filled ellipsoidal beam distributions have been studied theoretically, as they have had the promise of generating self-fields that produce forces linear in the coordinate offset in all three directions. More recently, a scheme for producing such distributions, which depends on the strong longitudinal expansion of an initially very short beam under its own space charge forces, has been proposed. Here we present the experimental demonstration of this scheme, obtained by illuminating the cathode in an rf photogun with an ultra-short laser pulse (~35 fs rms) with an appropriate transverse profile. The resulting 4 MeV beam spatiotemporal (x,t) distribution is imaged using an rf deflecting cavity with 50 fsec resolution. A temporal asymmetry in the ellipsoidal profile, due to image charge effects at the photocathode, is observed at higher charge operation. This distortion is also found to degrade the transverse beam quality.

MOPP076	L-Band RF Gun with a Thermionic Cathode	gun, simulation, emittance, controls	727
	S. Nagaitsev, R. Andrews, M. Church, A. Lunin, O. A. Nezhevenko, N. Solyak, D. Sun, V. P. Yakovlev Fermilab, Batavia, Illinois
	In this talk we present a design for an L-band (1.3 GHz) rf gun with a two-grid thermionic cathode assembly. The rf gun is design to provide a 10-mA average beam current for 1ms at 5 Hz. These parameters match the requirements of both the ILC and Fermilab Project X test facilities. In our simulations we are able to attain the bunch length at 20-30 degrees (FW), while the output energy can vary 2-4 MeV. We will present the results of our simulations as well as preliminary designs.

MOPP100	Performance of Compact Electron Injector on Evanescent Oscillations	electron, gun, coupling, resonance	790
	V. V. Mytrochenko, M. I. Ayzatskiy, I. V. Khodak, K. Kramarenko, V. A. Kushnir, A. Opanasenko, S. A. Perezhogin, D. L. Stepin, Z. V. Zhiglo NSC/KIPT, Kharkov
	An injector on the basis of a resonator structure with exponentially increasing amplitude of the electric field along an axis was developed at NSC KIPT. The injector is supplied with RF power through a rectangular-to-coaxial waveguide transition to provide axial symmetry of the accelerating field. The injector was designed to provide the output current up to 1 A at particle energy up to 1 MeV. Results of the injector test are presented in the work. Results obtained are compared with calculated ones.

MOPP103	High Field Gradient RF System for Bunch Rotation in PRISM-FFAG	impedance, power-supply, controls, synchrotron	796
	C. Ohmori KEK, Ibaraki M. Aoki, Y. Arimoto, I. Itahashi, Y. Kuno, Y. Kuriyama, A. Sato, M. Y. Yoshida Osaka University, Osaka Y. Iwashita Kyoto ICR, Uji, Kyoto Y. Mori KURRI, Osaka
	The PRISM project aims to supply a high quality muon beam using a wide aperture FFAG for mu-e conversion experiment. The low energy muon which has a large momentum spread will be manipulated in the FFAG using a bunch rotation technique with a low frequency RF around 3.5 MHz. Because of a short lifetime of muon, the rotation should be end in 5-6 turns in the FFAG and more than 2 MV is needed. The low frequency RF system using a magnetic alloy is designed to achieve a very high field gradient of more than 200 kV/m. The whole system is designed for a very low duty pulse operation to minimize the cost. The system has been modified to operate at 2 MHz for the beam test using alpha particle. A field gradient of more than 100 kV/m has been obtained by the preliminary test.

TUPC045	Setup and Commissioning of the Diagnostics Beamline for the SRF Photoinjector Project at Rossendorf	laser, electron, diagnostics, gun	1158
	T. Kamps, D. Böhlick, M. Dirsat, T. Quast, J. Rudolph, M. Schenk BESSY GmbH, Berlin A. Arnold, F. Staufenbiel, J. Teichert FZD, Dresden G. Klemz, I. Will MBI, Berlin D. Lipka DESY, Hamburg
	A superconducting radio frequency photo electron injector (SRF injector) has been developed by a collaboration of BESSY, DESY, FZD and MBI and is in operation since late 2007. After the initial commissioning in late 2007 with a Copper photocathode a Caesium-Telluride cathode was installed early 2008 to allow for high charge production. The longitudinal and transverse electron beam parameters are measured in a compact diagnostics beamline. This paper describes results from beam commissioning of the main diagnostic tools. Special emphasis is given on the bunch length measurement system for the 15 ps FWHM electron bunches. The system is based on the conversion of the electron pulses into radiation pulses by Cherenkov radiation. These radiation pulses are transported in a novel fully-reflective, relay imaging optical beamline to a streak camera, where the temporal properties of the pulses are measured. Results from beam measurements at 2pC (Copper cathode) and 1nC (Cesium-Telluride cathode) bunch charge are presented and discussed.

TUPC135	Experimental Determination of the Timing Stability of the Optical Synchronization System at FLASH	laser, electron, controls, polarization	1386
	F. Loehl, V. R. Arsov, M. Felber, K. E. Hacker, B. Lorbeer, F. Ludwig, K.-H. Matthiesen, H. Schlarb, B. Schmidt DESY, Hamburg S. Schulz, A. Winter, J. Zemella Uni HH, Hamburg
	An optical, drift free synchronization system with a stability of better than 10 fs is presently being installed at the free electron laser FLASH. A periodic laser pulse train from a mode-locked, erbium doped fiber laser is distributed via length stabilized fiber links. In this paper, we present measurements of the timing stability of the optical distribution system. Two arrival time monitors (BAM) are used to measure the electron bunch arrival times at two positions in the linac separated by 60 m. Each BAM is supplied with fiber-laser pulses by its own fiber link. By correlating the measured arrival times of the same electron bunches, the overall performance of the optical distribution system and the BAMs can be evaluated. A resolution and timing stability of better than 30 fs has beed reached.

TUPD027	Commissioning of the Offline-teststand for the S-DALINAC Polarized Injector SPIN	electron, polarization, scattering, laser	1482
	C. Heßler, R. Barday, U. Bonnes, M. Brunken, C. Eckardt, R. Eichhorn, J. Enders, M. Platz, Y. Poltoratska, M. Roth TU Darmstadt, Darmstadt W. Ackermann, W. F.O. Müller, B. Steiner, T. Weiland TEMF, Darmstadt K. Aulenbacher IKP, Mainz
	At the superconducting Darmstadt linear electron accelerator S-DALINAC a new injector for polarized electrons is under development. For this purpose an off-line test stand has been constructed. It consists of the source of polarized electrons and a test beamline including a Wien filter for spin manipulation, a Mott polarimeter for polarization measurement and various beam steering and diagnostic elements. The polarized electron beam is produced by photoemission from a strained GaAs cathode. We report on the status of this project and present first results of the measurements of the beam properties. We also give an outlook on the upcoming installation of SPIN at the S-DALINAC.

TUPD041	The Design of a 5 MeV Accelerator Based on Multipactor Electron Gun	electron, gun, emittance, coupling	1520
	M. Zhong, C.-X. Tang, S. Zheng TUB, Beijing
	The Multipactor Electron Gun (MPG) based on the multipactor effect can produce short duration, high current and self-bunching electron beams. This paper presents our work on the design of an S-band accelerator based on MPG and the result of preliminary experiment. The mechanical structure was designed with ability of replacing secondary electron emitters. Pd-Ba alloy and Pt were used as the secondary electron emitters of the MPG. The distance between electrodes and the resonant frequency of the MPG can be adjusted separately by step motors. The parameter of the accelerator tube was optimized using numerical simulation with the design outlet energy of the electron is 5MeV and an average current of 100mA.

TUPP071	Development of TiN Coating System for Beam Ducts of KEK B-factory	electron, positron, controls, luminosity	1700
	K. Shibata, H. Hisamatsu, K.-I. Kanazawa, M. Shirai, Y. Suetsugu KEK, Ibaraki
	A titanium nitride (TiN) coating system for the copper beam ducts of KEK B-factory (KEKB) was developed to reduce the secondary electron yield (SEY) from the inner surface, which would mitigate the electron cloud instability. The coating was done by DC magnetron sputtering of titanium in argon and nitrogen atmospheres. The duct was set vertically, and a titanium cathode rod was hung from the top on the center axis of the duct. A magnetic field was supplied by a movable solenoid coil placed outside of the duct. Preliminary experiments using small copper samples showed that a 200-nanometer-thick TiN film coated at 150 degree is the best from the viewpoints of SEY and adhesion strength. The SEY of the coated sample decreased to 60% of that of non-coated copper after an electron dose of 0.01 C/mm2, and the maximum SEY was 0.84. Using this system, five ducts with a length of up to 3.6 m were successfully coated. Some of them were installed into the KEKB positron ring last summer, and no problem was found in the following beam operation with a beam current of up to 1.6 A. One coated duct with an electron monitor was installed this winter, and the effect of the coating will be checked.

TUPP103	The Performance of 3D Space Charge Models for High Brightness Electron Bunches	space-charge, simulation, brightness, electron	1770
	G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock K. Floettmann DESY, Hamburg
	Precise and fast 3D space charge calculations for high brightness, low emittance electron beams are of growing importance for the design of future accelerators and light sources. The program package Astra (A space charge tracking algorithm) has been successfully used in the design of linac and rf photo injector systems. The Astra suite originally developed by K. Flöttmann tracks macro particles through user defined external fields including the space charge field of the particle cloud. In this paper we investigate the performance of the 3D space charge models implemented in Astra. These are the FFT-Poisson solver with the integrated Green's function and the iterative Poisson solver based on the multigrid technique. The numerical tests consider the accuracy of the solvers for model bunches as well as the performance within a typical simulation for the XFEL.

TUPP121	Spatial Resolution and Contrast of the Intensity Modulated Electron Beam by the Photocathode RF Gun for the Radiation Therapy	electron, gun, laser, radiation	1809
	T. Kondoh, K. Kan, H. Kashima, K. Norizawa, A. Ogata, S. Tagawa, J. Yang, Y. Yoshida ISIR, Osaka
	The radiation therapy of cancer is developing to un-uniform irradiation as the Intensity Modulated Radiation Therapy (IMRT), for reduce dose to normal tissue. Toward the IMRT, optical modulation of electron beam is studying by a photocathode RF gun. The photocathode RF gun can generate a low emittance electron beam by laser light. Because of the low emittance beam, the modulated electron beam is able to accelerate keeping shape. Electron beam were monitored by CCD cameras measuring the luminescence of the scintillator. Fundamental data such as the spatial resolution and the contrast of the optical intensity modulated electron beam are necessary. Spatial Resolution and Contrast of the Intensity Modulated Electron Beam by a Photocathode RF Gun will be reported. If the shape of the modulated electron beam is different, it may not keep beam shape from the non-symmetrically of the repulsion of the bunch inside. It will be reported that the relations of the beam-shape and the keeping ability of beam.

TUPP141	Electron Accelerators for Cleaning Flue Gases and for Oil Liquefaction	electron, radiation, vacuum, plasma	1848
	S. Korenev, R. P. Johnson Muons, Inc, Batavia
	High-power electron beams can be used to reduce the environmental impact of coal and oil-fired power generating plants by removing harmful materials from flue gases. This technology has been tested in the laboratory and at smaller industrial levels, but to make it economically attractive, the accelerator costs must be reduced and the efficiency must be increased for removing toxic components in low concentrations. We propose a simple electron accelerator with a wide beam to reduce costs. To remove toxic materials we propose a plasma reactor for desulfurization and selective catalytic reduction. The designs of 0.5 to 1.0 MeV accelerators with 20 to 100 kW average power are considered, along with the design of a plasma reactor for flue gas treatment. The design of a pilot facility for the oil industry is also presented.

TUPP161	60 keV 30 kW Electron Beam Facility for Electron Beam Technology	electron, controls, gun, focusing	1887
	Yu. I. Semenov, V. E. Akimov, M. A. Batazova, B. A. Dovzhenko, V. V. Ershov, A. R. Frolov, I. A. Gusev, Ye. A. Gusev, V. M. Konstantinov, N. Kh. Kot, V. R. Kozak, E. A. Kuper, G. I. Kuznetsov, P. V. Logatchev, V. R. Mamkin, A. S. Medvedko, I. V. Nikolaev, A. Yu. Protopopov, D. N. Pureskin, V. V. Repkov, A. N. Selivanov, D. V. Senkov, A. S. Tsyganov, A. A. Zharikov BINP SB RAS, Novosibirsk
	At the Budker Institute of Nuclear Physics, Novosibirsk, the 60 keV 30 kW electron beam facility for electron beam technology has been developed. The electron gun provides continuous or modulated beam within the current range from 1 mA up to 500 mA. The optical system allows both static and dynamic focusing of the electron beam within the 50/500 mm range of distance from the gun outlet, the beam scanning and its parallel displacement from the optical axis. The electron gun facility is controlled by the computer via the CAN interface. This paper presents the general description of the facility, its block diagram and main parameters.

WEOBM04	LHC: The World's Largest Vacuum Systems being Commissioned at CERN	vacuum, ion, cryogenics, injection	1959
	J. M. Jimenez CERN, Geneva
	When it switches on in the spring of 2008, the 26.7 km Large Hadron Collider (LHC) at CERN, will have the world's largest vacuum system operating over a wide range of pressures and employing an impressive array of vacuum technologies. This system is composed by 54 km of UHV vacuum for the circulating beams and 24 km of insulation vacuum around the cryogenic magnets operated mainly at 1.9 K. Over the 54 km of UHV beam vacuum, 48 km of this must be at cryogenic temperature (1.9 K). The remaining 6 km of beam vacuum containing the insertions is at ambient temperature and uses non-evaporable getter (NEG) coatings – a vacuum technology that was born and industrialized at CERN. The pumping is completed using 600 ion pumps to remove noble gases and 1000 gauges are used to monitor the pressures. The cryogenic insulation vacuum, while technically less demanding, is impressive by its size - 24 km in length, 900 mm in diameter for a total volume of 640 m³. Once cooled at 1.9 K, the cryogenic pumping allows reaching pressure in the 10^-6 mbar range. This paper described the entire vacuum system and the challenges of the design, manufacturing, installation and commissioning phases.
	Slides

WEPC069	A Possible THz Radiation Source with a Train of Short Pulses in the SPARC High Brightness Photoinjector	radiation, electron, simulation, linac	2154
	M. Boscolo, M. Castellano, E. Chiadroni, M. Ferrario, A. Stella, C. Vaccarezza INFN/LNF, Frascati (Roma) V. Petrillo Universita' degli Studi di Milano, Milano
	A radiofrequency electron gun followed by a compressor can generate trains of THz sub-picosecond electron pulses by illuminating the photocathode with a comb laser pulse. This structure of the beam can be used to produce coherent radiation. A feasibility study for a possible experiment at SPARC to be realized with the addition of a dedicated magnetic chicane is discussed. An optimization study of a magnetic chicane with a negative and variable R56 is studied, together with a set of parameters relative to the SPARC machine with the intent of demonstrating the feasibility of this experiment. The dynamics is studied within the SPARC system with the PARMELA code and with the RETAR code for the evaluation of the radiation.

WEPC087	New Preinjector for the ESRF Linac	gun, emittance, simulation, bunching	2195
	T. P. Perron, B. Ogier, A. Panzarella, E. Plouviez, E. Rabeuf, V. Serriere ESRF, Grenoble
	A new preinjector of the 200 MeV Linac is under manufacture at the ESRF. Two operation modes are foreseen, a short pulse of 1ns-.4nC and a long pulse of 1000ns-10nC. The new triode type thermionic 100 Kev gun has been characterized experimentally. The transverse and longitudinal phase space measurements are compared with simulations. The design and the expected performance of the final set-up which includes vertical deflecting plates, pre-bunching and bunching sections will be presented.

WEPC094	Thermo-Cathode RF Gun for BINP Race-Track Microtron-Recuperator	emittance, gun, injection, bunching	2213
	V. Volkov, E. Kendjebulatov, S. A. Krutikhin, G. Y. Kurkin, V. M. Petrov, I. K. Sedlyarov, N. Vinokurov BINP SB RAS, Novosibirsk
	In 2007 the thermo-cathode RF gun for the Budker INP energy recovery linac (ERL) was designed. The RF gun is capable to emit the electron bunches with the energy of 300 keV, average current of 100 mA, and repetition frequency of 90 MHz. The new injector is adapted to the existing RF system for beam bunching, accelerating and injecting to the linac of the microtron. Its advantage is the absence of high potential of 300 kV at the control circuits of the cathode; therefore the maintenance is simplified. Also due to the absence of the cathode back bombardment by residual gas ions in the RF cavity, the lifetime of the cathode is increased and the obtaining of the repetition frequency up to 90 MHz becomes feasible. In the paper the main characteristics of the injector, its design and results of beam dynamics calculations with optimised regimes are presented.

WEPP105	First Operation Results of the Superconducting Photoinjector at ELBE	gun, laser, electron, diagnostics	2755
	J. Teichert, A. Arnold, A. Buechner, H. Buettig, D. Janssen, M. Justus, U. Lehnert, P. Michel, P. Murcek, R. Schurig, G. Staats, F. Staufenbiel, R. Xiang FZD, Dresden T. Kamps BESSY GmbH, Berlin G. Klemz, I. Will MBI, Berlin A. Matheisen DESY, Hamburg
	In November 2007 the first electron beam was generated from the superconducting RF photo electron gun installed at the ELBE linear accelerator facility. The injector together with a sophisticated laser system and a diagnostic beam line were developed and constructed within a collaboration of BESSY, DESY, MBI and FZD. Delivering a CW beam with up to 1 mA average current, a significant improvement of the beam quality like an increase of the bunch charge up to 1 nC and a reduced transverse emittance will be obtained. After the cool-down of the cryostat the RF properties of the 3½-cell niobium cavity like pass band mode frequencies, unloaded quality factor versus accelerating gradient, Lorentz force detuning, and He pressure influence were measured. The first beam was extracted of a Cu photo cathode using a 262 nm UV laser system with a repetition rate of 100 kHz and about 0.4 W laser power. Later, caesium telluride photo cathodes will be applied. The installed diagnostics allow beam current, energy, energy spread, transverse emittance and bunch length measurements of the beam. The results of these measurements and the operational experiences with the gun will be presented.

WEPP136	Femtosecond and Attosecond Bunches of Electrons upon Field Emission in a Combined Quasi-static and Laser Electric Field	electron, laser, radiation, single-bunch	2812
	V. A. Papadichev LPI, Moscow
	Obtaining short pulses of particles and of electromagnetic radiation is of interest for investigating fast processes in physics, chemistry, biology and medicine,. A new method of modulating an electron beam is proposed to obtain electron bunches of 100-as to 20-fs duration. For this purpose, two electric fields – quasi-static and the variable field of a laser with wavelength in the 0.25 – to 10 microns range – simultaneously act on a single-spiked or multi-spiked cathode. Current from 0.01 to 100 A from one spike having a curvature radius of 1 micron corresponds to a maximal intensity of total electric field of 70 to 280 MV/cm for a 10-micron laser wavelength. For a 1-micron laser, total fields of 300 – 400 MV/cm should be used for 1 – 20 A currents. A regime of device operation was determined for which the emitting surface of a copper cathode is not damaged. Obtaining a single bunch or a sequence of bunches with a repetition rate up to1330 THz was considered. Using multi-spiked cathodes permits to obtain bunches with current up to 10 kA. P. Emma. Issues and challenges for short pulse radiation production, Proc. EPAC04, p. 225, Lucerne, Suisse. **S. Rimjuem et al. Generation of femtosecond electron pulses, Proc. EPAC04, p. 431.

WEPP137	Accelerating and Transporting Attosecond and Femtosecond Bunches of Electrons	electron, laser, space-charge, vacuum	2815
	V. A. Papadichev LPI, Moscow
	Dynamics of short bunches of electrons obtained upon field emission in a quasi-static electric field and a variable electric field of a laser has been studied. The equation of longitudinal motion of electrons was numerically integrated. Emitted electrons are accelerated by quasi-static potential applied to the spike and this drastically reduces initial energy spread in the bunch preventing its fast elongation. When the forces of space charge have little effect, grouping part of the beam due to velocity spread acquired in the laser field permits to obtain bunches of about 200-as duration when using a carbon dioxide laser and about 6-as with a neodymium laser. Analytical models were used to evaluate the influence of the space charge of the bunch on the longitudinal motion of electrons in it. It has been shown that the proper choice of the intensities of both fields can cancel such an influence. There have been considered methods of lateral focusing of the beam taking into account possible initial angular divergence and space charge effects. Such electron bunches could be used directly in experiments or for generation of short pulses of coherent UV- and X-ray radiation. V. A. Papadichev, Femtosecond and Attosecond Bunches of Electrons Upon Field Emission in a Combined Quasi-static and Laser Electric Field, submitted to this Conference.

THPC084	Studies of Electromagnetic Space-charge Fields in RF Photocathode Guns	space-charge, emittance, gun, simulation	3182
	C. S. Park, M. Hess IUCF, Bloomington, Indiana
	In high-brightness rf photocathode guns, the effects of space-charge can be important. In an effort to accurately simulate the effects of these space-charge fields without the presence of numerical grid dispersion, a Green’s function based code called IRPSS (Indiana Rf Photocathode Source Simulator) was developed. In this paper, we show the results of numerical simulations of the Argonne Wakefield Accelerator photocathode gun using IRPSS, and compare them with the results of an electrostatic based simulation code. In addition, we show how electromagnetic space-charge fields can affect the designs of photocathode gun magnetic focusing schemes, such as emittance compensation. We will also show how a multipole moment method can be effectively utilized to compute the reflections of electromagnetic space-charge fields due to irises in photocathode guns. M. Hess, C. S. Park, and D. Bolton. Phys. Rev. ST Accel. Beams 10, 054201 (2007).

THPC087	Electron Traps and Advanced Turbulence Diagnostic	electron, laser, controls, diagnostics	3191
	M. Cavenago INFN/LNL, Legnaro, Padova G. Bettega, F. Cavaliere, R. Pozzoli, M. Rome INFN-Milano, Milano
	In the electron trap Eltrap both trapped and propagating beam (along the magnetic field axis z) up to 20 kV can be studied. Beam structures in x and y (transverse plane) were successfully detected. Main diagnostic and axial control of instabilities was based on electrostatic. The addition of an external electron source, controlled by a laser, makes ns electron bunches now possible. A system to dump the electron beam off axis is also described. Faster diagnostic and control methods can be tested. In particular, Thompson scattering diagnostic of beam structures can be tested, considering that a wavelength shift (even if modest) is present. Nonlinear dynamics modeling of injection process is also described.

THPC091	Experimental Study of an Intense Relativistic Helical Electron Beam Formed with Interception of the Electrons Reflected from the Magnetic Mirror	electron, gun, space-charge, radiation	3200
	E. V. Ilyakov, I. S. Kulagin, S. V. Kuzikov, A. S. Shevchenko IAP/RAS, Nizhny Novgorod V. N. Manuilov NNGU, Nizhny Novgorod
	A new method of formation of pulsed intense relativistic helical electron beams (HEBs) for gyroresonant devices has been presented. The method is aimed at the increase of pitch-factor and the reduction of HEB velocity spread and is intended for use in the formation systems of laminar HEBs characterized by low influence of space charge on their parameters. The method is based on the operation of a special diaphragm located at one of minima of trajectories at the beginning of the transportation channel. The diaphragm diameter is chosen so that the electrons with the lowest oscillatory velocities cannot bend round the diaphragm and settle on it. The rest electrons pass by moving in the increasing magnetic field. Then, the electrons with the greatest oscillatory velocities are adiabatically reflected from the magnetic mirror between the electron gun and the transportation channel and settle on the back of the same diaphragm. Reduction of space charge of the reflected electrons has led to the increase of HEB pitch-factor (HEBs have been formed with the record of pitch-factors exceeding 2), while the accumulation of space charge worsens the HEB provoking modulation of formed HEB current.

THPP058	Progress with Electron Beam System for the Tevatron Electron Lenses	electron, gun, proton, simulation	3500
	V. Kamerdzhiev, G. F. Kuznetsov, G. W. Saewert, V. D. Shiltsev Fermilab, Batavia, Illinois
	We have developed , built and tested two novel electron guns for the Tevatron and RHIC electron lenses: the first, a gridded gun which generates electron beam profile with smoothed edges and broad flat-top; the second, Gaussian beam profile gun which can be used for generation of the profile with depressed emission in the center. We have also developed a new type of HV modulator for use in TELs. In this articel, we desicribe the guns and the modulator, and present results of the bench tests.

THPP107	Lifetime Comparisons of Single and Double Layered HBC-Foils using 3.2MeV Ne⁺ Ion Beam	ion, vacuum, target, radiation	3617
	I. Sugai, Y. Irie, H. Kawakami, M. Oyaizu, A. Takagi, Y. Takeda KEK, Ibaraki T. Hattori, K. K. Kawasaki RLNR, Tokyo
	The Japan-Proton Accelerator Research Complex (J-PARC) requires thick carbon stripper foils of 300-500 μg/cm² thick to strip electrons from the H-beam supplied by the linac before injection into the RCS. The energy depositions upon foil by the intense circulating proton bunched beam as well as H-beam result in the foil temperature of ~1800K. Thus, conventional carbon stripper foils will rupture in a very short time and even a high quality diamond foil will be broken at around 1800 K. Therfore, thick carbon stripper foils with high durability even at 1800K are indispensable for such accelerators. We have developed HBC (Hybrid type Boron mixed Carbon)-foil. We have measured the lifetime of a double and single-layered HBC-foils, diamond (DM) foils and commercially available carbon (CM) foils for comparisons using 3.2 MeV Ne⁺ ion beam, in which a significant amount of energy loss is deposited in the foils. The lifetime of the double-layered HBC- foil (180 μg/cm² x 2) was found to be long 18 and 446 times longer than those of DM-foil (360μg/cm² x 1) and double-layered CM foils ( 207μg/cm² x 2), respectively.

THPP137	Development of Vacuum Components for XFEL/SPring-8	vacuum, undulator, ion, target	3682
	T. Bizen RIKEN/SPring-8, Hyogo
	Several new vacuum components have been developed for the XFEL/SPring-8 project. Vacuum waveguide flanges for C-band and S-band were successfully developed. These flanges provide both RF seal and vacuum seal. This seal mechanism can make vacuum seal even with a scratched gasket. A solid-lubricated clean bolt was developed for C-band and S-band flanges to avoid organic dust pollution that induce multipactor. New vacuum flange for accelerator beam line can use three types of gasket. A small RF contact for 28 mm inside diameter bellows was developed. This unfixed RF contact can move freely in all directions and displaced large.