IPAC2011 - List of Authors (Spataro, B.)

Paper

Title

Page

Status of High Power Tests of Normal Conducting Short Standing Wave Structures*

241

V.A. Dolgashev, Z. Li, S.G. Tantawi, A.D. Yeremian
SLAC, Menlo Park, California, USA
Y. Higashi
KEK, Ibaraki, Japan
B. Spataro
INFN/LNF, Frascati (Roma), Italy

Funding: Work Supported by Doe Contract No. DE-AC02-76SF00515
We report results of continuing high power tests of short standing wave structures. These tests are part of an experimental and theoretical study of basic physics of rf breakdown in 11.4 GHz, normal conducting structures. The goal of this study is to determine the accelerating gradient capability of normal conducting rf powered particle accelerators. We have tested structures of different geometries, cell joining techniques, and materials. We found that the breakdown rate dependence on peak magnetic fields is stronger than on peak surface electric fields for cylindrically symmetric structures powered via a TM01 mode launcher. We report test results for structures powered by side-coupled rectangular waveguides. We found that increased rf magnetic field due to the side-coupling increases the breakdown rate as compared to the same accelerating gradient in cylindrically symmetric structures.

WEPC107

Development of a Steady State Simulation Code for Klystron Amplifiers

2265

C. Marrelli
CERN, Geneva, Switzerland
M. Migliorati, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
B. Spataro
INFN/LNF, Frascati (Roma), Italy
S.G. Tantawi
SLAC, Menlo Park, California, USA

The design of klystrons is based on the intensive utilization of simulation codes, which can evaluate the complete beam-cavities interaction in the case of large signals. In the present work, we present the development of a 2-D steady state simulation code that can self-consistently evaluate the effects of the electromagnetic field on the particles and of the particles back on the field. The algorithm is based on the iterative solution of the power balance equation in the RF structures and allows determining the amplitude and phase of the electromagnetic field starting from the cavity modes. Some applications of the code to a single cavity and a two cavity klystron are presented and compared with the results obtained from other codes. The effect of the space charge forces in the klystron drift tubes is also evaluated.

TUPO008

Electron Linac Optimization for Driving Bright Gamma-ray Sources based on Compton Back-scattering

1461

L. Serafini, F. Broggi, C. De Martinis, D. Giove
Istituto Nazionale di Fisica Nucleare, Milano, Italy
D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, E. Chiadroni, G. Di Pirro, A. Esposito, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, P. Tomassini, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
C. Maroli, V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
M. Migliorati, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy

We study the optimal lay-out and RF frequency for a room temperature GeV-class Electron Linac aiming at producing electron beams that enhance gamma-ray sources based on Compton back-scattering. These emerging novel sources, generating tunable, mono-chromatic, bright photon beams in the range of 5-20 MeV for nuclear physics as well as nuclear engineering, rely on both, high quality electron beams and J-class high repetition-rate synchronized laser systems in order to achieve the maximum spectral density of the gamma-ray beam (# photons/sec/eV). The best option among the conventionally used RF linac-bands (S, C, X) and possible hybrid schemes will be analyzed and discussed, focusing the study in terms of best performances for the gamma-ray source, its reliability and compactness. We show that the best possible candidates for a Gamma-ray driver are quite similar to those of FEL Linacs.

THYB01

Advanced Beam Manipulation Techniques at SPARC

2877

A. Mostacci, D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
B. Marchetti
INFN-Roma II, Roma, Italy
M. Migliorati
University of Rome "La Sapienza", Rome, Italy
L. Palumbo
Rome University La Sapienza, Roma, Italy
V. Petrillo, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

SPARC in Frascati is a high brightness photo-injector used to drive Free Electron Laser experiments and explore advanced beam manipulation techniques. The R&D effort made for the optimization of the beam parameters will be presented here, together with the major experimental results achieved. In particular, we will focus on the generation of sub-picosecond, high brightness electron bunch trains via velocity bunching technique (the so called comb beam). Such bunch trains can be used to drive tunable and narrow band THz sources, FELs and plasma wake field accelerators.

Slides THYB01 [20.772 MB]

THPS102

Novel Schemes for the Narrow Band Sparc THz Source using a Comb like e-beam

3672

B. Marchetti
INFN-Roma II, Roma, Italy
M. Boscolo, M. Castellano, E. Chiadroni, M. Ferrario, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

The development of radiation sources in the THz spectral region has become more and more interesting because of the peculiar characteristics of this radiation: it is non ionizing, it penetrates dielectrics, it is highly absorbed by polar liquids, highly reflected by metals and reveals specific "fingerprint" absorption spectra arising from fundamentals physical processes. The THz source at SPARC is an accelerator based source for research investigations (e.g. material science, biology fields). By means of e-beam manipulation technique, a longitudinal modulated beam, the so-called comb beam, can be produced at Sparc. In terms of THz sources, such e-beam distribution allows to produce high intensitiy narrow band THz radiation, whose spectrum strongly depends on the charge distribution inside the e-beam. Different linac schemes are compared. In particular, spectra obtained using the comb-beam compression through velocity bunching including a IV harmonic RF section is showed.

THPC159

Factory Acceptance Test of COLDDIAG: A Cold Vacuum Chamber for Diagnostics

3263

S. Gerstl, T. Baumbach, S. Casalbuoni, A.W. Grau, M. Hagelstein, T. Holubek, D. Saez de Jauregui
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
V. Baglin
CERN, Geneva, Switzerland
C. Boffo, G. Sikler
BNG, Würzburg, Germany
T.W. Bradshaw
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
R. Cimino, M. Commisso, A. Mostacci, B. Spataro
INFN/LNF, Frascati (Roma), Italy
J.A. Clarke, R.M. Jones, D.J. Scott
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M.P. Cox, J.C. Schouten
Diamond, Oxfordshire, United Kingdom
I.R.R. Shinton
UMAN, Manchester, United Kingdom
E.J. Wallén
MAX-lab, Lund, Sweden
R. Weigel
Max-Planck Institute for Metal Research, Stuttgart, Germany

Superconductive insertion devices (IDs) have higher fields for a given gap and period length compared with the state-of-the-art technology of permanent magnet IDs. One of the still open issues for the development of superconductive insertion devices is the understanding of the heat intake from the electron beam. With the aim of measuring the beam heat load to a cold bore and the hope to gain a deeper understanding in the underlying mechanisms, a cold vacuum chamber for diagnostics was built. It is equipped with the following instrumentation: retarding field analyzers to measure the electron flux, temperature sensors to measure the beam heat load, pressure gauges, and mass spectrometers to measure the gas content. The flexibility of the engineering design will allow the installation of the cryostat in different synchrotron light sources. The installation in the storage ring of the Diamond Light Source is foreseen in November 2011. Here we report about the technical design of this device, the factory acceptance test and the planned measurements with electron beam.

THPZ004

DAΦNE Tune-up for the KLOE-2 Experiment

3687

C. Milardi, D. Alesini, M.E. Biagini, S. Bini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G.O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, M. Esposito, L.G. Foggetta, A. Gallo, A. Ghigo, S. Guiducci, C. Ligi, S.M. Liuzzo, F. Marcellini, G. Mazzitelli, L. Pellegrino, M.A. Preger, L. Quintieri, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Zobov
INFN/LNF, Frascati (Roma), Italy
S. Bettoni
PSI, Villigen, Switzerland

Funding: Work supported by the EuCARD research programme within the 'Assessment of Novel Accelerator Concepts' work package (ANAC-WP11).
In its continuous evolution DAΦNE, the Frascati lepton collider, is starting a new run for the KLOE-2 experiment, an upgraded version of the KLOE one. A new interaction region, based on the high luminosity Crab-Waist collision scheme, has been designed, built and installed. Several machine subsystems have been revised according to innovative design concepts in order to improve beam dynamics. Collimators and shieldings have been upgraded in order to minimize the background rates on the detector during coasting as well as injection operation. A wide measurement campaign has been undertaken to verify and quantify the effect of the modifications and to tune-up the collider in view of the 3 years long data-taking foreseen to deliver ~5 fb-1 to the experiment.

Paper	Title	Page
MOPC071	Status of High Power Tests of Normal Conducting Short Standing Wave Structures*	241
	V.A. Dolgashev, Z. Li, S.G. Tantawi, A.D. Yeremian SLAC, Menlo Park, California, USA Y. Higashi KEK, Ibaraki, Japan B. Spataro INFN/LNF, Frascati (Roma), Italy
	Funding: Work Supported by Doe Contract No. DE-AC02-76SF00515 We report results of continuing high power tests of short standing wave structures. These tests are part of an experimental and theoretical study of basic physics of rf breakdown in 11.4 GHz, normal conducting structures. The goal of this study is to determine the accelerating gradient capability of normal conducting rf powered particle accelerators. We have tested structures of different geometries, cell joining techniques, and materials. We found that the breakdown rate dependence on peak magnetic fields is stronger than on peak surface electric fields for cylindrically symmetric structures powered via a TM01 mode launcher. We report test results for structures powered by side-coupled rectangular waveguides. We found that increased rf magnetic field due to the side-coupling increases the breakdown rate as compared to the same accelerating gradient in cylindrically symmetric structures.

WEPC107	Development of a Steady State Simulation Code for Klystron Amplifiers	2265
	C. Marrelli CERN, Geneva, Switzerland M. Migliorati, A. Mostacci, L. Palumbo Rome University La Sapienza, Roma, Italy B. Spataro INFN/LNF, Frascati (Roma), Italy S.G. Tantawi SLAC, Menlo Park, California, USA
	The design of klystrons is based on the intensive utilization of simulation codes, which can evaluate the complete beam-cavities interaction in the case of large signals. In the present work, we present the development of a 2-D steady state simulation code that can self-consistently evaluate the effects of the electromagnetic field on the particles and of the particles back on the field. The algorithm is based on the iterative solution of the power balance equation in the RF structures and allows determining the amplitude and phase of the electromagnetic field starting from the cavity modes. Some applications of the code to a single cavity and a two cavity klystron are presented and compared with the results obtained from other codes. The effect of the space charge forces in the klystron drift tubes is also evaluated.

TUPO008	Electron Linac Optimization for Driving Bright Gamma-ray Sources based on Compton Back-scattering	1461
	L. Serafini, F. Broggi, C. De Martinis, D. Giove Istituto Nazionale di Fisica Nucleare, Milano, Italy D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, E. Chiadroni, G. Di Pirro, A. Esposito, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, P. Tomassini, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy C. Maroli, V. Petrillo Universita' degli Studi di Milano, Milano, Italy M. Migliorati, A. Mostacci, L. Palumbo Rome University La Sapienza, Roma, Italy
	We study the optimal lay-out and RF frequency for a room temperature GeV-class Electron Linac aiming at producing electron beams that enhance gamma-ray sources based on Compton back-scattering. These emerging novel sources, generating tunable, mono-chromatic, bright photon beams in the range of 5-20 MeV for nuclear physics as well as nuclear engineering, rely on both, high quality electron beams and J-class high repetition-rate synchronized laser systems in order to achieve the maximum spectral density of the gamma-ray beam (# photons/sec/eV). The best option among the conventionally used RF linac-bands (S, C, X) and possible hybrid schemes will be analyzed and discussed, focusing the study in terms of best performances for the gamma-ray source, its reliability and compactness. We show that the best possible candidates for a Gamma-ray driver are quite similar to those of FEL Linacs.

THYB01	Advanced Beam Manipulation Techniques at SPARC	2877
	A. Mostacci, D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy B. Marchetti INFN-Roma II, Roma, Italy M. Migliorati University of Rome "La Sapienza", Rome, Italy L. Palumbo Rome University La Sapienza, Roma, Italy V. Petrillo, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma), Italy
	SPARC in Frascati is a high brightness photo-injector used to drive Free Electron Laser experiments and explore advanced beam manipulation techniques. The R&D effort made for the optimization of the beam parameters will be presented here, together with the major experimental results achieved. In particular, we will focus on the generation of sub-picosecond, high brightness electron bunch trains via velocity bunching technique (the so called comb beam). Such bunch trains can be used to drive tunable and narrow band THz sources, FELs and plasma wake field accelerators.
	Slides THYB01 [20.772 MB]

THPS102	Novel Schemes for the Narrow Band Sparc THz Source using a Comb like e-beam	3672
	B. Marchetti INFN-Roma II, Roma, Italy M. Boscolo, M. Castellano, E. Chiadroni, M. Ferrario, B. Spataro, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma), Italy
	The development of radiation sources in the THz spectral region has become more and more interesting because of the peculiar characteristics of this radiation: it is non ionizing, it penetrates dielectrics, it is highly absorbed by polar liquids, highly reflected by metals and reveals specific "fingerprint" absorption spectra arising from fundamentals physical processes. The THz source at SPARC is an accelerator based source for research investigations (e.g. material science, biology fields). By means of e-beam manipulation technique, a longitudinal modulated beam, the so-called comb beam, can be produced at Sparc. In terms of THz sources, such e-beam distribution allows to produce high intensitiy narrow band THz radiation, whose spectrum strongly depends on the charge distribution inside the e-beam. Different linac schemes are compared. In particular, spectra obtained using the comb-beam compression through velocity bunching including a IV harmonic RF section is showed.

THPC159	Factory Acceptance Test of COLDDIAG: A Cold Vacuum Chamber for Diagnostics	3263
	S. Gerstl, T. Baumbach, S. Casalbuoni, A.W. Grau, M. Hagelstein, T. Holubek, D. Saez de Jauregui Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany V. Baglin CERN, Geneva, Switzerland C. Boffo, G. Sikler BNG, Würzburg, Germany T.W. Bradshaw STFC/RAL, Chilton, Didcot, Oxon, United Kingdom R. Cimino, M. Commisso, A. Mostacci, B. Spataro INFN/LNF, Frascati (Roma), Italy J.A. Clarke, R.M. Jones, D.J. Scott Cockcroft Institute, Warrington, Cheshire, United Kingdom M.P. Cox, J.C. Schouten Diamond, Oxfordshire, United Kingdom I.R.R. Shinton UMAN, Manchester, United Kingdom E.J. Wallén MAX-lab, Lund, Sweden R. Weigel Max-Planck Institute for Metal Research, Stuttgart, Germany
	Superconductive insertion devices (IDs) have higher fields for a given gap and period length compared with the state-of-the-art technology of permanent magnet IDs. One of the still open issues for the development of superconductive insertion devices is the understanding of the heat intake from the electron beam. With the aim of measuring the beam heat load to a cold bore and the hope to gain a deeper understanding in the underlying mechanisms, a cold vacuum chamber for diagnostics was built. It is equipped with the following instrumentation: retarding field analyzers to measure the electron flux, temperature sensors to measure the beam heat load, pressure gauges, and mass spectrometers to measure the gas content. The flexibility of the engineering design will allow the installation of the cryostat in different synchrotron light sources. The installation in the storage ring of the Diamond Light Source is foreseen in November 2011. Here we report about the technical design of this device, the factory acceptance test and the planned measurements with electron beam.

THPZ004	DAΦNE Tune-up for the KLOE-2 Experiment	3687
	C. Milardi, D. Alesini, M.E. Biagini, S. Bini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G.O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, M. Esposito, L.G. Foggetta, A. Gallo, A. Ghigo, S. Guiducci, C. Ligi, S.M. Liuzzo, F. Marcellini, G. Mazzitelli, L. Pellegrino, M.A. Preger, L. Quintieri, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Zobov INFN/LNF, Frascati (Roma), Italy S. Bettoni PSI, Villigen, Switzerland
	Funding: Work supported by the EuCARD research programme within the 'Assessment of Novel Accelerator Concepts' work package (ANAC-WP11). In its continuous evolution DAΦNE, the Frascati lepton collider, is starting a new run for the KLOE-2 experiment, an upgraded version of the KLOE one. A new interaction region, based on the high luminosity Crab-Waist collision scheme, has been designed, built and installed. Several machine subsystems have been revised according to innovative design concepts in order to improve beam dynamics. Collimators and shieldings have been upgraded in order to minimize the background rates on the detector during coasting as well as injection operation. A wide measurement campaign has been undertaken to verify and quantify the effect of the modifications and to tune-up the collider in view of the 3 years long data-taking foreseen to deliver ~5 fb-1 to the experiment.