LINAC2012 - List of Keywords (cathode)

Paper	Title	Other Keywords	Page
SUPB024	Development of Permanent Magnet Focusing System for Klystrons	klystron, focusing, permanent-magnet, simulation	62
	Y. Fuwa, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan S. Fukuda, S. Michizono KEK, Ibaraki, Japan
	The Distributed RF System (DRFS) for the International Linear Collider (ILC) requires thousands of klystrons. The failure rate of the power supply for solenoid focusing coil of each klystron may be a critical issue for a regular operation of the ILC. A permanent magnet beam focusing system can increase reliability and eliminate their power consumption. Since the required magnetic field is not high in this system, inexpensive anisotropic ferrite magnets can be used instead of magnets containing rare earth materials. In order to prove its feasibility, a test model of a permanent magnet focusing beam system is constructed and a power test of the klystron for DRFS with this model is under preparation. The results of magnetic field distribution measurement and the power test will be presented.

MOPB013	Experimental Results on the PHIL Photo-injector Test Stand at LAL	electron, emittance, laser, gun	198
	R. Roux, F. Blot, J. Brossard, C. Bruni, S. Cavalier, J-N. Cayla, V. Chaumat, M. El Khaldi, A. Gonnin, P. Lepercq, E.N. Mandag, B. Mercier, H. Monard, C. Prevost, V. Soskov, A. Variola LAL, Orsay, France
	Since the first beam in November 2009 of the alphaX S-band RF gun, upgrades of the beamline have been carried out. Several YAG screens based transverse dimensions monitors have been installed as well as supplementary charge diagnostics. We will present a detailed experimental characterization of the RF gun performances such as emittance measurement using a solenoid scan and energy spread as a function of the RF phase. Most of the accelerator operation and experimental results have been carried out with a copper photo-cathode. PHIL being a test stand for photo-injectors, we have also tested a magnesium photo-cathode with the aim of higher charge per bunch thanks to its higher quantum efficiency. We will report on the results of this experiment. In May 2012, a new RF gun, the PHIN gun, will be installed. This gun which is also a S-band 2,5 cells is a copy of the one that LAL built for the CLIC Test Facility 3 at CERN. In the future, we plan to use this gun to produce a high charge up to 10nC with CsTe photo-cathodes introduced in the gun from a UHV transfer chamber. Preliminary tests and measurements of the beam produced by this gun with a copper photo-cathode will be presented.

MOPB025	1ms Multi-bunch Electron Beam Acceleration by a Normal Conducting RF Gun and Superconducting Accelerator	gun, laser, cavity, emittance	228
	M. Kuriki, S. Hosoda, H. Iijima HU/AdSM, Higashi-Hiroshima, Japan H. Hayano, J. Urakawa, K. Watanabe KEK, Ibaraki, Japan G. Isoyama, R. Kato, K. Kawase ISIR, Osaka, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan A. Kuramoto Sokendai, Ibaraki, Japan K. Sakaue RISE, Tokyo, Japan
	Funding: Quantum Beam Project by MEXT, Japan We perform electron beam generation and acceleration of 1 ms long pulse and multi-bunch format at KEK-STF (Superconducting Test Facility). The 1 ms long pulse beam is generated by a normal conducting photo-cathode L-band RF gun. The beam is boosted up to 40 MeV by a super-conducting accelerator. Aim of STF is to establish the super-conducting accelerator technology for ILC (International Linear Collider). The facility is concurrently used to demonstrate high brightness X-ray generation by inverse laser Compton scattering supported by MEXT Quantum Beam project. The RF gun cavity has been fabricated by DESY-FNAL-KEK collaboration. After conditioning process, a stable operation of the cavity up to 4.0 MW RF input with 1 ms pulse was achieved by keeping low dark current. 1 ms pulse generation and acceleration has been confirmed in March 2012. Quasi-monochromatic X-ray generation experiment by Laser-Compton will be carried out at STF from the next coming July. We report the latest status of STF.

MOPB029	Commissioning of the X-Band Test Area at SLAC	gun, laser, injection, electron	234
	C. Limborg-Deprey, C. Adolphsen, M.P. Dunning, S. Gilevich, C. Hast, R.K. Jobe, D.J. McCormick, A. Miahnahri, T.O. Raubenheimer, A.E. Vlieks, D.R. Walz, S.P. Weathersby SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515. The X-Band Test Area (XTA) is being assembled in the NLCTA tunnel at SLAC to serve as a test facility for new X-Band RF guns. The first gun to be tested is an upgraded version of the 5.6 cell, 200 MV/m peak field X-band gun designed at SLAC in 2003 for the Compton Scattering experiment run in ASTA [1]. The XTA beamline is equipped with diagnostics to measure both the longitudinal phase space and the transverse phase space properties of the beam after it has reached 100 MeV. We will review design choices and present some early commissioning results. [1] A.E. Vlieks, et al. “Recent measurements and plans for the SLAC Compton X-ray source”, SLAC-PUB-11689, 2006. 10pp. Published in AIP Conf. Proc.807:481-490, 2006

MOPB064	Developing of Superconducting RF Guns at BNL	gun, SRF, cavity, electron	324
	S.A. Belomestnykh, Z. Altinbas, I. Ben-Zvi, J.C. Brutus, D.M. Gassner, H. Hahn, L.R. Hammons, J.P. Jamilkowski, D. Kayran, J. Kewisch, V. Litvinenko, G.J. Mahler, G.T. McIntyre, D. Pate, D. Phillips, T. Rao, S.K. Seberg, T. Seda, B. Sheehy, J. Skaritka, K.S. Smith, R. Than, J.E. Tuozzolo, E. Wang, Q. Wu, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, J. Dai, M. Ruiz-Osés, T. Xin Stony Brook University, Stony Brook, USA C.H. Boulware, T.L. Grimm Niowave, Inc., Lansing, Michigan, USA A. Burrill JLAB, Newport News, Virginia, USA R. Calaga CERN, Geneva, Switzerland M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd AES, Medford, NY, USA X. Liang SBU, Stony Brook, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The work at Niowave is supported by the US DOE under SBIR contract No. DE-FG02-07ER84861. BNL is developing several superconducting RF guns for different applications. The first gun is based on a half-cell 1.3 GHz elliptical cavity. This gun is used to study generation of polarized electrons from GaAs photocathodes. The second gun, also of a half-cell elliptical cavity design, operates at 704 MHz and is designed to produce high average current electron beam for the ERL prototype from a multi-alkali photocathodes. The third gun is of a quarter-wave resonator type, operating at 112 MHz. This gun will be used for photocathode studies, including a diamond-amplified cathode, and to generate high charge, low repetition rate beam for the coherent electron cooling experiment. In this presentation we will briefly describe the gun designs, present recent test results and discuss future plans.

TUPLB01	The Swiss FEL RF Gun: RF Design and Thermal Analysis	gun, coupling, electron, linac	442
	J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer PSI, Villigen, Switzerland
	We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.
	Slides TUPLB01 [1.679 MB]

TUPLB04	Results of Testing of Multi-beam Klystrons for the European XFEL	klystron, high-voltage, vacuum, status	448
	V. Vogel, L. Butkowski, A. Cherepenko, S. Choroba, I. Harders, J. Hartung DESY, Hamburg, Germany
	For the European XFEL multi-beam klystrons, which can produce RF power of 10 MW at an RF frequency of 1.3 GHz, at 1.5 ms pulse length and 10 Hz repetition rate, were chosen as RF power sources. Twenty-seven of horizontal multi-beam klystrons (MBK) together with connection modules (CM) will be installed in the XFEL underground tunnel. The CM will be installed on the MBK and connects the MBK to the pulse transformer with only one HV cable, because the CM has a filament transformer inside as well as all diagnostics for HV and cathode current measurements. MBK prototypes together with CM prototypes have been tested for long time at a test stand at DESY, about 3000 hours of operation for each of horizontal MBK with full RF output power, full pulse length and repetition rate of 10 Hz. Testing of first MBKs from series production has been started. In this paper we will give an overview of the test procedure, summarize the current test results and we will give a comparison of the most important parameters.

TUPLB12	Development of Permanent Magnet Focusing System for Klystrons	klystron, focusing, permanent-magnet, simulation	470
	Y. Fuwa, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan S. Fukuda, S. Michizono KEK, Ibaraki, Japan
	The Distributed RF System (DRFS) for the International Linear Collider (ILC) requires thousands of klystrons. The failure rate of the power supply for solenoid focusing coil of each klystron may be a critical issue for a regular operation of the ILC. A permanent magnet beam focusing system can increase reliability and eliminate their power consumption. Since the required magnetic field is not high in this system, inexpensive anisotropic ferrite magnets can be used instead of magnets containing rare earth materials. In order to prove its feasibility, a test model of a permanent magnet focusing beam system is constructed and a power test of the klystron for DRFS with this model is under preparation. The results of magnetic field distribution measurement and the power test will be presented.
	Slides TUPLB12 [1.357 MB]

TUPB004	Results of Testing of Multi-beam Klystrons for the European XFEL	klystron, high-voltage, vacuum, status	479
	V. Vogel, L. Butkowski, A. Cherepenko, S. Choroba, I. Harders, J. Hartung DESY, Hamburg, Germany
	For the European XFEL multi-beam klystrons, which can produce RF power of 10 MW at an RF frequency of 1.3 GHz, at 1.5ms pulse length and 10 Hz repetition rate, were chosen as RF power sources. Twenty-seven of horizontal multi-beam klystrons (MBK) together with connection modules (CM) will be installed in the XFEL underground tunnel. The CM will be installed on the MBK and connects the MBK to the pulse transformer with only one HV cable, because the CM has a filament transformer inside as well as all diagnostics for HV and cathode current measurements. MBK prototypes together with CM prototypes have been tested for long time at a test stand at DESY, about 3000 hours of operation for each of horizontal MBK with full RF output power, full pulse length and repetition rate of 10 Hz. Testing of first MBKs from series production has been started. In this paper we will give an overview of the test procedure, summarize the current test results and we will give a comparison of the most important parameters.

TUPB008	Major Trends in Linac Design for X-ray FELs	electron, FEL, linac, emittance	489
	A. Zholents ANL, Argonne, USA
	Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357. Major trends in the contemporary linac designs for x-ray free-electron lasers (XFELs) are outlined starting with identification of the key performance parameters, continuing with considerations of the design options for the electron gun and linac, and finishing with electron beam manipulation in the phase space.

TUPB010	The Swiss FEL RF Gun: RF Design and Thermal Analysis	gun, coupling, electron, linac	495
	J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer PSI, Villigen, Switzerland
	We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.

TUPB090	Development of Permanent Magnet Focusing System for Klystrons	klystron, focusing, permanent-magnet, simulation	669
	Y. Fuwa, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan S. Fukuda, S. Michizono KEK, Ibaraki, Japan
	A permanent magnet focusing system for klystrons is under development to improve reliability of RF supply system and reduce power consumption. To save production cost, anisotropic ferrite magnets are used in this system. A test model has been fabricated and the power test of a 750 kW klystron with this focusing magnet is carried out. 60 % of the nominal output power has been achieved at a preliminary power test so far

THPLB12	Photoinjector SRF Cavity Development for BERLinPro	cavity, gun, HOM, emittance	837
	A. Neumann, W. Anders, T. Kamps, J. Knobloch HZB, Berlin, Germany E.N. Zaplatin FZJ, Jülich, Germany
	In 2010 HZB has received approval to build BERLinPro, an ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.5 MeV kinetic energy while limited by fundamental power coupler performance to about 200 kW forward power. In oder to achieve these goals the injector cavity is being developed in a three stage approach. The current design studies focus on implementing a normal conducting cathode insert into a newly developed superconducting photoinjector cavity. In this paper the fundamental RF design calculations concerning cell shape for optimized beam dynamics as well as SRF performance will be presented. Further studies concentrate on the HZDR based choke cell design to implement the high quantum efficiency normal conducting cathode with the SRF cavity.
	Slides THPLB12 [1.431 MB]

THPB066	Photoinjector SRF Cavity Development for BERLinPro	cavity, gun, HOM, emittance	993
	A. Neumann, W. Anders, T. Kamps, J. Knobloch HZB, Berlin, Germany E.N. Zaplatin FZJ, Jülich, Germany
	In 2010 HZB has received approval to build BERLinPro, an ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.5 MeV kinetic energy while limited by fundamental power coupler performance to about 200 kW forward power. In oder to achieve these goals the injector cavity is being developed in a three stage approach. The current design studies focus on implementing a normal conducting cathode insert into a newly developed superconducting photoinjector cavity. In this paper the fundamental RF design calculations concerning cell shape for optimized beam dynamics as well as SRF performance will be presented. Further studies concentrate on the HZDR based choke cell design to implement the high quantum efficiency normal conducting cathode with the SRF cavity.

THPB068	First Observation of Photoemission Enhancement from Copper Cathode Illuminated by Z-Polarized Laser Pulse	laser, polarization, gun, focusing	996
	H. Tomizawa, H. Dewa, A. Mizuno, T. Taniuchi JASRI/SPring-8, Hyogo, Japan
	Since 2006, we have developed a novel photocathode gun gated by laser-induced Schottky-effect. This new type of gun utilizes a laser’s coherency to aim at a compact femtosecond laser oscillator as an IR laser source using Z-polarization on the photocathode. This Z-polarization scheme reduces the laser photon energy (making it possible to excite the cathode with a longer wavelength) by reducing the work function of cathode due to Schottky effect. A hollow laser incidence is applied with a hollow convex lens in a vacuum that is focused after passing the laser beam through a radial polarizer. According to our calculations (convex lens: NA=0.15), a Z-field of 1 GV/m needs 1.26 MW at peak power for the fundamental wavelength (792 nm). In the first demonstration of Z-field emission, enhancement was done with a copper cathode at THG (264 nm). Consequently, we observed 1.4 times enhancement of photoemission at 1.6 GV/m of an averaged laser Z-field on the cathode surface. We report the first observation and analysis of the emission enhancements with this laser-induced Schottky-effect on metal copper photocathodes by comparing radial and azimuthal polarizations of the incident laser pulses.

THPB073	Initial RF Tests of the Diamond S-Band Photocathode Gun	gun, cavity, coupling, controls	1002
	C. Christou, S.A. Pande Diamond, Oxfordshire, United Kingdom
	An S-band photocathode electron gun designed to operate at repetition rates up to 1 kHz CW has been designed at Diamond and manufactured at FMB. The first test results of this gun are presented. Low-power RF measurements have been carried out to verify the RF design of the gun, and high-power conditioning and RF test has begun. Initial high power tests have been carried out at 5 Hz repetition rate using the S-band RF plant normally used to power the Diamond linac: the benefits and limitations of this approach are considered, together with plans for further testing. J. H. Han et al, NIM A 647(2011) 17-24

Paper

Title

Other Keywords

Page

SUPB024

Development of Permanent Magnet Focusing System for Klystrons

klystron, focusing, permanent-magnet, simulation

62

Y. Fuwa, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
S. Fukuda, S. Michizono
KEK, Ibaraki, Japan

The Distributed RF System (DRFS) for the International Linear Collider (ILC) requires thousands of klystrons. The failure rate of the power supply for solenoid focusing coil of each klystron may be a critical issue for a regular operation of the ILC. A permanent magnet beam focusing system can increase reliability and eliminate their power consumption. Since the required magnetic field is not high in this system, inexpensive anisotropic ferrite magnets can be used instead of magnets containing rare earth materials. In order to prove its feasibility, a test model of a permanent magnet focusing beam system is constructed and a power test of the klystron for DRFS with this model is under preparation. The results of magnetic field distribution measurement and the power test will be presented.

MOPB013

Experimental Results on the PHIL Photo-injector Test Stand at LAL

electron, emittance, laser, gun

198

R. Roux, F. Blot, J. Brossard, C. Bruni, S. Cavalier, J-N. Cayla, V. Chaumat, M. El Khaldi, A. Gonnin, P. Lepercq, E.N. Mandag, B. Mercier, H. Monard, C. Prevost, V. Soskov, A. Variola
LAL, Orsay, France

Since the first beam in November 2009 of the alphaX S-band RF gun, upgrades of the beamline have been carried out. Several YAG screens based transverse dimensions monitors have been installed as well as supplementary charge diagnostics. We will present a detailed experimental characterization of the RF gun performances such as emittance measurement using a solenoid scan and energy spread as a function of the RF phase. Most of the accelerator operation and experimental results have been carried out with a copper photo-cathode. PHIL being a test stand for photo-injectors, we have also tested a magnesium photo-cathode with the aim of higher charge per bunch thanks to its higher quantum efficiency. We will report on the results of this experiment. In May 2012, a new RF gun, the PHIN gun, will be installed. This gun which is also a S-band 2,5 cells is a copy of the one that LAL built for the CLIC Test Facility 3 at CERN. In the future, we plan to use this gun to produce a high charge up to 10nC with CsTe photo-cathodes introduced in the gun from a UHV transfer chamber. Preliminary tests and measurements of the beam produced by this gun with a copper photo-cathode will be presented.

MOPB025

1ms Multi-bunch Electron Beam Acceleration by a Normal Conducting RF Gun and Superconducting Accelerator

gun, laser, cavity, emittance

228

M. Kuriki, S. Hosoda, H. Iijima
HU/AdSM, Higashi-Hiroshima, Japan
H. Hayano, J. Urakawa, K. Watanabe
KEK, Ibaraki, Japan
G. Isoyama, R. Kato, K. Kawase
ISIR, Osaka, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
A. Kuramoto
Sokendai, Ibaraki, Japan
K. Sakaue
RISE, Tokyo, Japan

Funding: Quantum Beam Project by MEXT, Japan
We perform electron beam generation and acceleration of 1 ms long pulse and multi-bunch format at KEK-STF (Superconducting Test Facility). The 1 ms long pulse beam is generated by a normal conducting photo-cathode L-band RF gun. The beam is boosted up to 40 MeV by a super-conducting accelerator. Aim of STF is to establish the super-conducting accelerator technology for ILC (International Linear Collider). The facility is concurrently used to demonstrate high brightness X-ray generation by inverse laser Compton scattering supported by MEXT Quantum Beam project. The RF gun cavity has been fabricated by DESY-FNAL-KEK collaboration. After conditioning process, a stable operation of the cavity up to 4.0 MW RF input with 1 ms pulse was achieved by keeping low dark current. 1 ms pulse generation and acceleration has been confirmed in March 2012. Quasi-monochromatic X-ray generation experiment by Laser-Compton will be carried out at STF from the next coming July. We report the latest status of STF.

MOPB029

Commissioning of the X-Band Test Area at SLAC

gun, laser, injection, electron

234

C. Limborg-Deprey, C. Adolphsen, M.P. Dunning, S. Gilevich, C. Hast, R.K. Jobe, D.J. McCormick, A. Miahnahri, T.O. Raubenheimer, A.E. Vlieks, D.R. Walz, S.P. Weathersby
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.
The X-Band Test Area (XTA) is being assembled in the NLCTA tunnel at SLAC to serve as a test facility for new X-Band RF guns. The first gun to be tested is an upgraded version of the 5.6 cell, 200 MV/m peak field X-band gun designed at SLAC in 2003 for the Compton Scattering experiment run in ASTA [1]. The XTA beamline is equipped with diagnostics to measure both the longitudinal phase space and the transverse phase space properties of the beam after it has reached 100 MeV. We will review design choices and present some early commissioning results.
[1] A.E. Vlieks, et al. “Recent measurements and plans for the SLAC Compton X-ray source”, SLAC-PUB-11689, 2006. 10pp. Published in AIP Conf. Proc.807:481-490, 2006

MOPB064

Developing of Superconducting RF Guns at BNL

gun, SRF, cavity, electron

324

S.A. Belomestnykh, Z. Altinbas, I. Ben-Zvi, J.C. Brutus, D.M. Gassner, H. Hahn, L.R. Hammons, J.P. Jamilkowski, D. Kayran, J. Kewisch, V. Litvinenko, G.J. Mahler, G.T. McIntyre, D. Pate, D. Phillips, T. Rao, S.K. Seberg, T. Seda, B. Sheehy, J. Skaritka, K.S. Smith, R. Than, J.E. Tuozzolo, E. Wang, Q. Wu, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, J. Dai, M. Ruiz-Osés, T. Xin
Stony Brook University, Stony Brook, USA
C.H. Boulware, T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA
A. Burrill
JLAB, Newport News, Virginia, USA
R. Calaga
CERN, Geneva, Switzerland
M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd
AES, Medford, NY, USA
X. Liang
SBU, Stony Brook, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The work at Niowave is supported by the US DOE under SBIR contract No. DE-FG02-07ER84861.
BNL is developing several superconducting RF guns for different applications. The first gun is based on a half-cell 1.3 GHz elliptical cavity. This gun is used to study generation of polarized electrons from GaAs photocathodes. The second gun, also of a half-cell elliptical cavity design, operates at 704 MHz and is designed to produce high average current electron beam for the ERL prototype from a multi-alkali photocathodes. The third gun is of a quarter-wave resonator type, operating at 112 MHz. This gun will be used for photocathode studies, including a diamond-amplified cathode, and to generate high charge, low repetition rate beam for the coherent electron cooling experiment. In this presentation we will briefly describe the gun designs, present recent test results and discuss future plans.

TUPLB01

The Swiss FEL RF Gun: RF Design and Thermal Analysis

gun, coupling, electron, linac

442

J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer
PSI, Villigen, Switzerland

We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.

Slides TUPLB01 [1.679 MB]

TUPLB04

Results of Testing of Multi-beam Klystrons for the European XFEL

klystron, high-voltage, vacuum, status

448

V. Vogel, L. Butkowski, A. Cherepenko, S. Choroba, I. Harders, J. Hartung
DESY, Hamburg, Germany

For the European XFEL multi-beam klystrons, which can produce RF power of 10 MW at an RF frequency of 1.3 GHz, at 1.5 ms pulse length and 10 Hz repetition rate, were chosen as RF power sources. Twenty-seven of horizontal multi-beam klystrons (MBK) together with connection modules (CM) will be installed in the XFEL underground tunnel. The CM will be installed on the MBK and connects the MBK to the pulse transformer with only one HV cable, because the CM has a filament transformer inside as well as all diagnostics for HV and cathode current measurements. MBK prototypes together with CM prototypes have been tested for long time at a test stand at DESY, about 3000 hours of operation for each of horizontal MBK with full RF output power, full pulse length and repetition rate of 10 Hz. Testing of first MBKs from series production has been started. In this paper we will give an overview of the test procedure, summarize the current test results and we will give a comparison of the most important parameters.

TUPLB12

Development of Permanent Magnet Focusing System for Klystrons

klystron, focusing, permanent-magnet, simulation

470

Y. Fuwa, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
S. Fukuda, S. Michizono
KEK, Ibaraki, Japan

The Distributed RF System (DRFS) for the International Linear Collider (ILC) requires thousands of klystrons. The failure rate of the power supply for solenoid focusing coil of each klystron may be a critical issue for a regular operation of the ILC. A permanent magnet beam focusing system can increase reliability and eliminate their power consumption. Since the required magnetic field is not high in this system, inexpensive anisotropic ferrite magnets can be used instead of magnets containing rare earth materials. In order to prove its feasibility, a test model of a permanent magnet focusing beam system is constructed and a power test of the klystron for DRFS with this model is under preparation. The results of magnetic field distribution measurement and the power test will be presented.

Slides TUPLB12 [1.357 MB]

TUPB004

Results of Testing of Multi-beam Klystrons for the European XFEL

klystron, high-voltage, vacuum, status

479

V. Vogel, L. Butkowski, A. Cherepenko, S. Choroba, I. Harders, J. Hartung
DESY, Hamburg, Germany

For the European XFEL multi-beam klystrons, which can produce RF power of 10 MW at an RF frequency of 1.3 GHz, at 1.5ms pulse length and 10 Hz repetition rate, were chosen as RF power sources. Twenty-seven of horizontal multi-beam klystrons (MBK) together with connection modules (CM) will be installed in the XFEL underground tunnel. The CM will be installed on the MBK and connects the MBK to the pulse transformer with only one HV cable, because the CM has a filament transformer inside as well as all diagnostics for HV and cathode current measurements. MBK prototypes together with CM prototypes have been tested for long time at a test stand at DESY, about 3000 hours of operation for each of horizontal MBK with full RF output power, full pulse length and repetition rate of 10 Hz. Testing of first MBKs from series production has been started. In this paper we will give an overview of the test procedure, summarize the current test results and we will give a comparison of the most important parameters.

TUPB008

Major Trends in Linac Design for X-ray FELs

electron, FEL, linac, emittance

489

A. Zholents
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357.
Major trends in the contemporary linac designs for x-ray free-electron lasers (XFELs) are outlined starting with identification of the key performance parameters, continuing with considerations of the design options for the electron gun and linac, and finishing with electron beam manipulation in the phase space.

TUPB010

The Swiss FEL RF Gun: RF Design and Thermal Analysis

gun, coupling, electron, linac

495

J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer
PSI, Villigen, Switzerland

We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.

TUPB090

Development of Permanent Magnet Focusing System for Klystrons

klystron, focusing, permanent-magnet, simulation

669

Y. Fuwa, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
S. Fukuda, S. Michizono
KEK, Ibaraki, Japan

A permanent magnet focusing system for klystrons is under development to improve reliability of RF supply system and reduce power consumption. To save production cost, anisotropic ferrite magnets are used in this system. A test model has been fabricated and the power test of a 750 kW klystron with this focusing magnet is carried out. 60 % of the nominal output power has been achieved at a preliminary power test so far

THPLB12

Photoinjector SRF Cavity Development for BERLinPro

cavity, gun, HOM, emittance

837

A. Neumann, W. Anders, T. Kamps, J. Knobloch
HZB, Berlin, Germany
E.N. Zaplatin
FZJ, Jülich, Germany

In 2010 HZB has received approval to build BERLinPro, an ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.5 MeV kinetic energy while limited by fundamental power coupler performance to about 200 kW forward power. In oder to achieve these goals the injector cavity is being developed in a three stage approach. The current design studies focus on implementing a normal conducting cathode insert into a newly developed superconducting photoinjector cavity. In this paper the fundamental RF design calculations concerning cell shape for optimized beam dynamics as well as SRF performance will be presented. Further studies concentrate on the HZDR based choke cell design to implement the high quantum efficiency normal conducting cathode with the SRF cavity.

Slides THPLB12 [1.431 MB]

THPB066

Photoinjector SRF Cavity Development for BERLinPro

cavity, gun, HOM, emittance

993

A. Neumann, W. Anders, T. Kamps, J. Knobloch
HZB, Berlin, Germany
E.N. Zaplatin
FZJ, Jülich, Germany

In 2010 HZB has received approval to build BERLinPro, an ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.5 MeV kinetic energy while limited by fundamental power coupler performance to about 200 kW forward power. In oder to achieve these goals the injector cavity is being developed in a three stage approach. The current design studies focus on implementing a normal conducting cathode insert into a newly developed superconducting photoinjector cavity. In this paper the fundamental RF design calculations concerning cell shape for optimized beam dynamics as well as SRF performance will be presented. Further studies concentrate on the HZDR based choke cell design to implement the high quantum efficiency normal conducting cathode with the SRF cavity.

THPB068

First Observation of Photoemission Enhancement from Copper Cathode Illuminated by Z-Polarized Laser Pulse

laser, polarization, gun, focusing

996

H. Tomizawa, H. Dewa, A. Mizuno, T. Taniuchi
JASRI/SPring-8, Hyogo, Japan

Since 2006, we have developed a novel photocathode gun gated by laser-induced Schottky-effect. This new type of gun utilizes a laser’s coherency to aim at a compact femtosecond laser oscillator as an IR laser source using Z-polarization on the photocathode. This Z-polarization scheme reduces the laser photon energy (making it possible to excite the cathode with a longer wavelength) by reducing the work function of cathode due to Schottky effect. A hollow laser incidence is applied with a hollow convex lens in a vacuum that is focused after passing the laser beam through a radial polarizer. According to our calculations (convex lens: NA=0.15), a Z-field of 1 GV/m needs 1.26 MW at peak power for the fundamental wavelength (792 nm). In the first demonstration of Z-field emission, enhancement was done with a copper cathode at THG (264 nm). Consequently, we observed 1.4 times enhancement of photoemission at 1.6 GV/m of an averaged laser Z-field on the cathode surface. We report the first observation and analysis of the emission enhancements with this laser-induced Schottky-effect on metal copper photocathodes by comparing radial and azimuthal polarizations of the incident laser pulses.

THPB073

Initial RF Tests of the Diamond S-Band Photocathode Gun

gun, cavity, coupling, controls

1002

C. Christou, S.A. Pande
Diamond, Oxfordshire, United Kingdom

An S-band photocathode electron gun designed to operate at repetition rates up to 1 kHz CW has been designed at Diamond and manufactured at FMB*. The first test results of this gun are presented. Low-power RF measurements have been carried out to verify the RF design of the gun, and high-power conditioning and RF test has begun. Initial high power tests have been carried out at 5 Hz repetition rate using the S-band RF plant normally used to power the Diamond linac: the benefits and limitations of this approach are considered, together with plans for further testing.
* J. H. Han et al, NIM A 647(2011) 17-24