IPAC2021 - List of Authors (Migliorati, M.)

Paper	Title	Page
MOPAB270	Beam Dynamics Studies in a Standing Wave Ka-band Linearizer	857
	J. Scifo, M. Behtouei, L. Faillace, M. Ferrario, A. Giribono, B. Spataro, C. Vaccarezza INFN/LNF, Frascati, Italy M. Migliorati INFN-Roma1, Rome, Italy M. Migliorati Sapienza University of Rome, Rome, Italy G. Torrisi INFN/LNS, Catania, Italy
	Next-generation FEL user facilities require high-quality electron beams with kA peak current. The combination of a high brightness RF injector and a magnetic compression stage represents a very performant solution in terms of electron beam emittance and peak current. One of the important issues is the design of a proper device that acts as a linearizer for the beam longitudinal phase space. Recently, the design of a SW Ka band RF accelerating structure has been proposed with promising results. The paper reports on electron beam dynamics studies in the described RF structure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB270
About •	paper received ※ 19 May 2021 paper accepted ※ 29 August 2021 issue date ※ 26 August 2021
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MOPAB353	Design of a compact Ka-Band Mode Launcher for High-gradient Accelerators	1100
	G. Torrisi, G.S. Mauro, G. Sorbello INFN/LNS, Catania, Italy M. Behtouei, L. Faillace, B. Spataro, A. Variola INFN/LNF, Frascati, Italy V.A. Dolgashev SLAC, Menlo Park, California, USA L. Faillace, M. Migliorati Sapienza University of Rome, Rome, Italy M. Migliorati INFN-Roma1, Rome, Italy J.B. Rosenzweig UCLA, Los Angeles, California, USA G. Sorbello University of Catania, Catania, Italy
	In this work, we present the RF design of a table-top Ka-Band mode launcher operating at 35.98 GHz. The structure consists of a symmetrical 4-port WR28 rectangular-TE10-to-circular-TM01 mode converter that is used to couple a peak output RF power of 5 MW (pulse length up to 50 ns and repetition rate up to 100 Hz) in Ka-Band linear accelerator able to achieve very high accelerating gradients (up to 200 MV/m). Numerical simulations have been carried out with the 3D full-wave commercial simulator Ansys HFSS in order to obtain a preliminary tuning of the accelerating field flatness at the operating frequency f0=35.98 GHz. The main RF parameters, such as reflection coefficient, transmission losses, and conversion efficiency are given together with a verification of the field azimuthal symmetry which avoids dipole and quadrupole deflecting modes. To simplify future manufacturing, reduce fabrication costs, and also reduce the probability of RF breakdown, the proposed new geometry has "open" configuration. This geometry eliminates the flow of RF currents through critical joints and allows this device to be milled from metal blocks.
	Poster MOPAB353 [3.131 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB353
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 27 August 2021
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WEPAB029	Challenges for the Interaction Region Design of the Future Circular Collider FCC-ee	2668
	M. Boscolo, A. Ciarma, F. Fransesini, L. Pellegrino INFN/LNF, Frascati, Italy N. Bacchetta INFN- Sez. di Padova, Padova, Italy M. Benedikt, H. Burkhardt, M.A. Jones, R. Kersevan, M. Lueckhof, E. Montbarbon, K. Oide, L. Watrelot, F. Zimmermann CERN, Meyrin, Switzerland L. Brunetti, M. Serluca IN2P3-LAPP, Annecy-le-Vieux, France M. Dam NBI, København, Denmark M. Koratzinos MIT, Cambridge, Massachusetts, USA M. Migliorati INFN-Roma1, Rome, Italy A. Novokhatski, M.K. Sullivan SLAC, Menlo Park, California, USA F. Poirier CNRS - DR17, RENNES, France
	Funding: This work was partially supported by the EC HORIZON 2020 project FCC-IS, grant agreement n.951754, and by the U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-76SF-00515. The FCC-ee is a proposed future high-energy, high-intensity and high precision lepton collider. Here, we present the latest developments for the FCC-ee interaction regions, which shall ensure optimum conditions for the particle physics experiments. We discuss measures of background reduction and a revised interaction region layout including a low impedance compact beam chamber design. We also discuss the possible impact of the radiation generated in the interaction region including beamstrahlung.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB029
About •	paper received ※ 11 May 2021 paper accepted ※ 23 June 2021 issue date ※ 30 August 2021
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WEPAB224	Update of the Transverse Proton Synchrotron Impedance Model	3149
	S. Joly, N. Mounet, B. Salvant CERN, Geneva, Switzerland S. Joly La Sapienza University of Rome, Rome, Italy M. Migliorati INFN-Roma1, Rome, Italy M. Migliorati Sapienza University of Rome, Rome, Italy
	The CERN Proton Synchrotron (PS) was recently upgraded to allow reaching the ambitious performance goal of the High-Luminosity LHC Project. This upgrade is part of the LHC Injectors Upgrade project. The final part of the upgrade was performed during Long Shutdown 2 (LS2) to allow injection at higher energy from the PS Booster and a twofold increase in beam intensity and brightness. These changes must be considered in the PS impedance model. The effect on the impedance of the removal of obsolete injection equipment, changes of several accelerator components and new injection energy will be reviewed, as well as the wall impedance of the elliptic beam pipe, thanks to a newly developed code that allows taking into account both the ellipticity and the non-ultra-relativistic nature of the beam.
	Poster WEPAB224 [0.654 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB224
About •	paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 17 August 2021
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WEPAB238	Modeling Short Range Wakefield Effects in a High Gradient Linac	3185
	F. Bosco, M. Carillo, L. Faillace, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo Sapienza University of Rome, Rome, Italy M. Behtouei, L. Faillace, A. Giribono, B. Spataro, C. Vaccarezza INFN/LNF, Frascati, Italy F. Bosco, M. Migliorati INFN-Roma1, Rome, Italy L. Giuliano, A. Mostacci, L. Palumbo INFN-Roma, Roma, Italy J.B. Rosenzweig UCLA, Los Angeles, California, USA
	Funding: This work is supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project. The interaction of charged beams with the surrounding accelerating structures requires a thorough investigation due to potential negative effects on the phase space quality. Indeed, the wakefields acting back on the beam are responsible for emittance dilution and instabilities, such as the beam break-up, which limit the performances of electron-based radiation sources and linear colliders. Here we introduce a new tracking code which is meant to investigate the effects of short-range transverse wakefields in linear accelerators. The tracking is based on quasi-analytical models for the beam dynamics which, in addition to the basic optics specified by the applied fields, include dipole wakefield forces and a simple approach to account for space-charge effects. Such features provide a reliable tool which easily allows to inspect the performances of a linac. To validate the model, a parallel analysis for a reference case is performed with well-known beam dynamics codes, and comparisons are shown. As an illustrative application, we discuss a study on alignment tolerances evaluating the emittance growth induced by misaligned accelerating sections.
	Poster WEPAB238 [1.747 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB238
About •	paper received ※ 18 May 2021 paper accepted ※ 07 July 2021 issue date ※ 01 September 2021
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WEPAB225	Transverse and Longitudinal Single Bunch Instabilities in FCC-ee	3153
	E. Carideo, D. Quartullo, F. Zimmermann CERN, Meyrin, Switzerland D. De Arcangelis Sapienza University of Rome, Rome, Italy M. Migliorati, M. Zobov INFN/LNF, Frascati, Italy
	Improving the accuracy of the impedance model of an accelerator is important for keeping beam instabilities and power loss under control. Here, by means of the PyHEAD- TAIL tracking code, we first review the longitudinal mi- crowave instability threshold for FCC-ee by taking into ac- count the longitudinal impedance model evaluated so far. Moreover, we present the results of beam dynamics simula- tions, including both the longitudinal and transverse wake- fields due to the resistive wall, in order to evaluate the influ- ence of the bunch length on the transverse mode coupling instability. The results of the transverse beam dynamics are also compared with the Vlasov solver DELPHI.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB225
About •	paper received ※ 10 May 2021 paper accepted ※ 01 July 2021 issue date ※ 18 August 2021
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MOPAB410	Preliminary Studies of a Compact VHEE Linear Accelerator System for FLASH Radiotherapy	1229
	L. Giuliano, F. Bosco, M. Carillo, D. De Arcangelis, L. Faillace, L. Ficcadenti, M. Migliorati, A. Mostacci, L. Palumbo Sapienza University of Rome, Rome, Italy D. Alesini, M. Behtouei, B. Spataro INFN/LNF, Frascati, Italy G. Cuttone, G. Torrisi INFN/LNS, Catania, Italy V. Favaudon, S. Heinrich, A. Patriarca Institut Curie - Centre de Protonthérapie d’Orsay, Orsay, France
	Funding: The work is supported by La Sapienza University, research grant "grandi progetti di ricerca 2020". The Flash Radio Therapy is a revolutionary new technique in the cancer cure: it spares healthy tissue from the damage of the ionizing radiation maintaining the tumor control as efficient as in conventional radiotherapy. To allow the implementation of the FLASH Therapy concept into actual clinical use, it is necessary to have a linear accelerator able to deliver the very high dose and very high dose rate (>10⁶ Gy/s) in a very short irradiation time (beam on time < 100ms). Low energy S-band Linacs (up to 7 MeV) are being used in Radiobiology and pre-clinic applications but in order to treat deep tumors, the energy of the electrons should achieve the range of 60-100 MeV. In this paper, we address the main issues in the design of a compact C band (5.712 GHz) electron linac-VHEE for FLASH Radio Therapy. We present preliminary studies on C-band structures at La Sapienza and at INFN-LNS, aiming to reach a high accelerating gradient and high current necessary to deliver a dose >1 Gy/pulse, with very short electron pulse.
	Poster MOPAB410 [0.650 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB410
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 21 August 2021
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WEPAB051	Beam Dynamics for a High Field C-Band Hybrid Photoinjector	2714
	L. Faillace, F. Bosco, M. Carillo, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo Sapienza University of Rome, Rome, Italy R.B. Agustsson, I.I. Gadjev, S.V. Kutsaev, A.Y. Murokh RadiaBeam, Santa Monica, California, USA M. Behtouei, A. Giribono, B. Spataro, C. Vaccarezza INFN/LNF, Frascati, Italy A. Fukasawa, N. Majernik, J.B. Rosenzweig, O. Williams UCLA, Los Angeles, California, USA S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National Committee V through the ARYA project. In this paper, we present a new class of a hybrid photoinjector in C-Band. This project is the effort result of a UCLA/Sapienza/INFN-LNF/SLAC/RadiaBeam collaboration. This device is an integrated structure consisting of an initial standing-wave 2.5-cell gun connected to a traveling-wave section at the input coupler. Such a scheme nearly avoids power reflection back to the klystron, removing the need for a high-power circulator. It also introduces strong velocity bunching due to a 90° phase shift in the accelerating field. A relatively high cathode electric field of 120 MV/m produces a ~4 MeV beam with ~20 MW input RF power in a small foot-print. The beam transverse dynamics are controlled with a ~0.27 T focusing solenoid. We show the simulation results of the RF/magnetic design and the optimized beam dynamics that shows 6D phase space compensation at 250 pC. Proper beam shaping at the cathode yields a ~0.5 mm-mrad transverse emittance. A beam waist occurs simultaneously with a longitudinal focus of <400 fs rms and peak current >600 A. We discuss application of this injector to an Inverse-Compton Scattering system and present corresponding start-to-end beam dynamics simulations.
	Poster WEPAB051 [0.827 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB051
About •	paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 15 August 2021
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WEPAB256	Three-Dimensional Space Charge Oscillations in a Hybrid Photoinjector	3240
	M. Carillo, M. Behtouei, F. Bosco, L. Faillace, A. Giribono, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo Sapienza University of Rome, Rome, Italy L. Ficcadenti INFN-Roma, Roma, Italy J.B. Rosenzweig UCLA, Los Angeles, California, USA B. Spataro, C. Vaccarezza INFN/LNF, Frascati, Italy
	Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project. A new hybrid C-band photo-injector, consisting of a standing wave RF gun connected to a traveling wave structure, operating in a velocity bunching regime, has shown to produce an extremely high brightness beam with very low emittance and a very high peak current through a simultaneous compression of the beam in the longitudinal and transverse dimensions. A beam slice analysis has been performed in order to understand the evolution of the relevant physical parameters of the beam in the longitudinal and transverse phase spaces along the structure. A simple model for the envelope equation has been developed to describe the beam behavior in this particular dynamics regime that we term "triple waist", since all three dimensions reach a minimum condition almost simultaneously. The model analyzes the transverse envelope dynamics at the exit of the hybrid photo-injector, in the downstream drift where the triple waist occurs. The analytical solutions obtained from the envelope equation are compared with the simulations, showing a good agreement. Finally, these results have been analyzed also in terms of plasma oscillation to obtain a further physical interpretation of the beam dynamics.
	Poster WEPAB256 [1.162 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB256
About •	paper received ※ 19 May 2021 paper accepted ※ 21 July 2021 issue date ※ 13 August 2021
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WEPAB398	A C-Band RF Mode Launcher with Quadrupole Field Components Cancellation for High Brightness Applications	3638
	G. Pedrocchi SBAI, Roma, Italy D. Alesini, F. Cardelli, A. Gallo, A. Giribono, B. Spataro INFN/LNF, Frascati, Italy G. Castorina AVO-ADAM, Meyrin, Switzerland L. Ficcadenti INFN-Roma, Roma, Italy M. Migliorati, A. Mostacci, L. Palumbo Sapienza University of Rome, Rome, Italy
	The R&D of high gradient radiofrequency devices is aimed to develop innovative and compact accelerating stuctures based on new manufactoring techniques and materials in order to produce devices operating with the highest accelerating gradient. Recent studies have shown a large increase in the maximum sustained RF surface electric fields in copper structure operating at cryogenic temperature. These novel approaches allow significant performance improvements of RF photoinjectors. Indeed the operation at high surface fields results in considerable increase of electron brilliance. This requires high field quality in the RF photoinjector and specifically in its poweer coupler. In this work we present a novel power coupler for the RF photoinjector. The coupler is a compact C-band TM01 mode launcher with a fourfold symmetry which minimized both the dipole and the quadrupole RF field components.
	Poster WEPAB398 [1.799 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB398
About •	paper received ※ 13 May 2021 paper accepted ※ 06 July 2021 issue date ※ 23 August 2021
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MOXC01	Combined Effect of Beam-Beam Interaction and Beam Coupling Impedance in Future Circular Colliders	25
	Y. Zhang, N. Wang IHEP, Beijing, People’s Republic of China E. Carideo CERN, Geneva, Switzerland M. Migliorati SBAI, Roma, Italy M. Zobov INFN/LNF, Frascati, Italy
	Funding: This work is supported by National Key Programme for S&T Research and Development, China (Grant No. 2016YFA0400400), National Natural Science Foundation of China (No. 11775238, No. 11775239). The future large scale electron-positron colliders, such as FCC-ee in Europe and CEPC in China, will rely on the crab waist collision scheme with a large Piwinski angle. Differently from the past generation colliders both luminosity and beam-beam tune shifts depend on the bunch length in such a collision scheme. In addition, for the future circular colliders with extreme beam parameters in collision several new effects become important such as beamstrahlung, coherent X-Z instability and 3D flip-flop. For all these effects the longitudinal beam dynamics plays an essential role and should be taken into account for the collider luminosity optimization. In this paper we discuss an impact of the longitudinal beam coupling impedance on the collider performance.
	Slides MOXC01 [2.269 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXC01
About •	paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 17 August 2021
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Paper

Title

Page

Beam Dynamics Studies in a Standing Wave Ka-band Linearizer

857

J. Scifo, M. Behtouei, L. Faillace, M. Ferrario, A. Giribono, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy
M. Migliorati
INFN-Roma1, Rome, Italy
M. Migliorati
Sapienza University of Rome, Rome, Italy
G. Torrisi
INFN/LNS, Catania, Italy

Next-generation FEL user facilities require high-quality electron beams with kA peak current. The combination of a high brightness RF injector and a magnetic compression stage represents a very performant solution in terms of electron beam emittance and peak current. One of the important issues is the design of a proper device that acts as a linearizer for the beam longitudinal phase space. Recently, the design of a SW Ka band RF accelerating structure has been proposed with promising results. The paper reports on electron beam dynamics studies in the described RF structure.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB270

About •

paper received ※ 19 May 2021 paper accepted ※ 29 August 2021 issue date ※ 26 August 2021

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MOPAB353

Design of a compact Ka-Band Mode Launcher for High-gradient Accelerators

1100

G. Torrisi, G.S. Mauro, G. Sorbello
INFN/LNS, Catania, Italy
M. Behtouei, L. Faillace, B. Spataro, A. Variola
INFN/LNF, Frascati, Italy
V.A. Dolgashev
SLAC, Menlo Park, California, USA
L. Faillace, M. Migliorati
Sapienza University of Rome, Rome, Italy
M. Migliorati
INFN-Roma1, Rome, Italy
J.B. Rosenzweig
UCLA, Los Angeles, California, USA
G. Sorbello
University of Catania, Catania, Italy

In this work, we present the RF design of a table-top Ka-Band mode launcher operating at 35.98 GHz. The structure consists of a symmetrical 4-port WR28 rectangular-TE10-to-circular-TM01 mode converter that is used to couple a peak output RF power of 5 MW (pulse length up to 50 ns and repetition rate up to 100 Hz) in Ka-Band linear accelerator able to achieve very high accelerating gradients (up to 200 MV/m). Numerical simulations have been carried out with the 3D full-wave commercial simulator Ansys HFSS in order to obtain a preliminary tuning of the accelerating field flatness at the operating frequency f0=35.98 GHz. The main RF parameters, such as reflection coefficient, transmission losses, and conversion efficiency are given together with a verification of the field azimuthal symmetry which avoids dipole and quadrupole deflecting modes. To simplify future manufacturing, reduce fabrication costs, and also reduce the probability of RF breakdown, the proposed new geometry has "open" configuration. This geometry eliminates the flow of RF currents through critical joints and allows this device to be milled from metal blocks.

Poster MOPAB353 [3.131 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB353

About •

paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 27 August 2021

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WEPAB029

Challenges for the Interaction Region Design of the Future Circular Collider FCC-ee

2668

M. Boscolo, A. Ciarma, F. Fransesini, L. Pellegrino
INFN/LNF, Frascati, Italy
N. Bacchetta
INFN- Sez. di Padova, Padova, Italy
M. Benedikt, H. Burkhardt, M.A. Jones, R. Kersevan, M. Lueckhof, E. Montbarbon, K. Oide, L. Watrelot, F. Zimmermann
CERN, Meyrin, Switzerland
L. Brunetti, M. Serluca
IN2P3-LAPP, Annecy-le-Vieux, France
M. Dam
NBI, København, Denmark
M. Koratzinos
MIT, Cambridge, Massachusetts, USA
M. Migliorati
INFN-Roma1, Rome, Italy
A. Novokhatski, M.K. Sullivan
SLAC, Menlo Park, California, USA
F. Poirier
CNRS - DR17, RENNES, France

Funding: This work was partially supported by the EC HORIZON 2020 project FCC-IS, grant agreement n.951754, and by the U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-76SF-00515.
The FCC-ee is a proposed future high-energy, high-intensity and high precision lepton collider. Here, we present the latest developments for the FCC-ee interaction regions, which shall ensure optimum conditions for the particle physics experiments. We discuss measures of background reduction and a revised interaction region layout including a low impedance compact beam chamber design. We also discuss the possible impact of the radiation generated in the interaction region including beamstrahlung.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB029

About •

paper received ※ 11 May 2021 paper accepted ※ 23 June 2021 issue date ※ 30 August 2021

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WEPAB224

Update of the Transverse Proton Synchrotron Impedance Model

3149

S. Joly, N. Mounet, B. Salvant
CERN, Geneva, Switzerland
S. Joly
La Sapienza University of Rome, Rome, Italy
M. Migliorati
INFN-Roma1, Rome, Italy
M. Migliorati
Sapienza University of Rome, Rome, Italy

The CERN Proton Synchrotron (PS) was recently upgraded to allow reaching the ambitious performance goal of the High-Luminosity LHC Project. This upgrade is part of the LHC Injectors Upgrade project. The final part of the upgrade was performed during Long Shutdown 2 (LS2) to allow injection at higher energy from the PS Booster and a twofold increase in beam intensity and brightness. These changes must be considered in the PS impedance model. The effect on the impedance of the removal of obsolete injection equipment, changes of several accelerator components and new injection energy will be reviewed, as well as the wall impedance of the elliptic beam pipe, thanks to a newly developed code that allows taking into account both the ellipticity and the non-ultra-relativistic nature of the beam.

Poster WEPAB224 [0.654 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB224

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paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 17 August 2021

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WEPAB238

Modeling Short Range Wakefield Effects in a High Gradient Linac

3185

F. Bosco, M. Carillo, L. Faillace, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
M. Behtouei, L. Faillace, A. Giribono, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy
F. Bosco, M. Migliorati
INFN-Roma1, Rome, Italy
L. Giuliano, A. Mostacci, L. Palumbo
INFN-Roma, Roma, Italy
J.B. Rosenzweig
UCLA, Los Angeles, California, USA

Funding: This work is supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project.
The interaction of charged beams with the surrounding accelerating structures requires a thorough investigation due to potential negative effects on the phase space quality. Indeed, the wakefields acting back on the beam are responsible for emittance dilution and instabilities, such as the beam break-up, which limit the performances of electron-based radiation sources and linear colliders. Here we introduce a new tracking code which is meant to investigate the effects of short-range transverse wakefields in linear accelerators. The tracking is based on quasi-analytical models for the beam dynamics which, in addition to the basic optics specified by the applied fields, include dipole wakefield forces and a simple approach to account for space-charge effects. Such features provide a reliable tool which easily allows to inspect the performances of a linac. To validate the model, a parallel analysis for a reference case is performed with well-known beam dynamics codes, and comparisons are shown. As an illustrative application, we discuss a study on alignment tolerances evaluating the emittance growth induced by misaligned accelerating sections.

Poster WEPAB238 [1.747 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB238

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paper received ※ 18 May 2021 paper accepted ※ 07 July 2021 issue date ※ 01 September 2021

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WEPAB225

Transverse and Longitudinal Single Bunch Instabilities in FCC-ee

3153

E. Carideo, D. Quartullo, F. Zimmermann
CERN, Meyrin, Switzerland
D. De Arcangelis
Sapienza University of Rome, Rome, Italy
M. Migliorati, M. Zobov
INFN/LNF, Frascati, Italy

Improving the accuracy of the impedance model of an accelerator is important for keeping beam instabilities and power loss under control. Here, by means of the PyHEAD- TAIL tracking code, we first review the longitudinal mi- crowave instability threshold for FCC-ee by taking into ac- count the longitudinal impedance model evaluated so far. Moreover, we present the results of beam dynamics simula- tions, including both the longitudinal and transverse wake- fields due to the resistive wall, in order to evaluate the influ- ence of the bunch length on the transverse mode coupling instability. The results of the transverse beam dynamics are also compared with the Vlasov solver DELPHI.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB225

About •

paper received ※ 10 May 2021 paper accepted ※ 01 July 2021 issue date ※ 18 August 2021

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MOPAB410

Preliminary Studies of a Compact VHEE Linear Accelerator System for FLASH Radiotherapy

1229

L. Giuliano, F. Bosco, M. Carillo, D. De Arcangelis, L. Faillace, L. Ficcadenti, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
D. Alesini, M. Behtouei, B. Spataro
INFN/LNF, Frascati, Italy
G. Cuttone, G. Torrisi
INFN/LNS, Catania, Italy
V. Favaudon, S. Heinrich, A. Patriarca
Institut Curie - Centre de Protonthérapie d’Orsay, Orsay, France

Funding: The work is supported by La Sapienza University, research grant "grandi progetti di ricerca 2020".
The Flash Radio Therapy is a revolutionary new technique in the cancer cure: it spares healthy tissue from the damage of the ionizing radiation maintaining the tumor control as efficient as in conventional radiotherapy. To allow the implementation of the FLASH Therapy concept into actual clinical use, it is necessary to have a linear accelerator able to deliver the very high dose and very high dose rate (>10⁶ Gy/s) in a very short irradiation time (beam on time < 100ms). Low energy S-band Linacs (up to 7 MeV) are being used in Radiobiology and pre-clinic applications but in order to treat deep tumors, the energy of the electrons should achieve the range of 60-100 MeV. In this paper, we address the main issues in the design of a compact C band (5.712 GHz) electron linac-VHEE for FLASH Radio Therapy. We present preliminary studies on C-band structures at La Sapienza and at INFN-LNS, aiming to reach a high accelerating gradient and high current necessary to deliver a dose >1 Gy/pulse, with very short electron pulse.

Poster MOPAB410 [0.650 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB410

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paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 21 August 2021

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WEPAB051

Beam Dynamics for a High Field C-Band Hybrid Photoinjector

2714

L. Faillace, F. Bosco, M. Carillo, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
R.B. Agustsson, I.I. Gadjev, S.V. Kutsaev, A.Y. Murokh
RadiaBeam, Santa Monica, California, USA
M. Behtouei, A. Giribono, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy
A. Fukasawa, N. Majernik, J.B. Rosenzweig, O. Williams
UCLA, Los Angeles, California, USA
S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National Committee V through the ARYA project.
In this paper, we present a new class of a hybrid photoinjector in C-Band. This project is the effort result of a UCLA/Sapienza/INFN-LNF/SLAC/RadiaBeam collaboration. This device is an integrated structure consisting of an initial standing-wave 2.5-cell gun connected to a traveling-wave section at the input coupler. Such a scheme nearly avoids power reflection back to the klystron, removing the need for a high-power circulator. It also introduces strong velocity bunching due to a 90° phase shift in the accelerating field. A relatively high cathode electric field of 120 MV/m produces a ~4 MeV beam with ~20 MW input RF power in a small foot-print. The beam transverse dynamics are controlled with a ~0.27 T focusing solenoid. We show the simulation results of the RF/magnetic design and the optimized beam dynamics that shows 6D phase space compensation at 250 pC. Proper beam shaping at the cathode yields a ~0.5 mm-mrad transverse emittance. A beam waist occurs simultaneously with a longitudinal focus of <400 fs rms and peak current >600 A. We discuss application of this injector to an Inverse-Compton Scattering system and present corresponding start-to-end beam dynamics simulations.

Poster WEPAB051 [0.827 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB051

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paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 15 August 2021

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WEPAB256

Three-Dimensional Space Charge Oscillations in a Hybrid Photoinjector

3240

M. Carillo, M. Behtouei, F. Bosco, L. Faillace, A. Giribono, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
L. Ficcadenti
INFN-Roma, Roma, Italy
J.B. Rosenzweig
UCLA, Los Angeles, California, USA
B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy

Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project.
A new hybrid C-band photo-injector, consisting of a standing wave RF gun connected to a traveling wave structure, operating in a velocity bunching regime, has shown to produce an extremely high brightness beam with very low emittance and a very high peak current through a simultaneous compression of the beam in the longitudinal and transverse dimensions. A beam slice analysis has been performed in order to understand the evolution of the relevant physical parameters of the beam in the longitudinal and transverse phase spaces along the structure. A simple model for the envelope equation has been developed to describe the beam behavior in this particular dynamics regime that we term "triple waist", since all three dimensions reach a minimum condition almost simultaneously. The model analyzes the transverse envelope dynamics at the exit of the hybrid photo-injector, in the downstream drift where the triple waist occurs. The analytical solutions obtained from the envelope equation are compared with the simulations, showing a good agreement. Finally, these results have been analyzed also in terms of plasma oscillation to obtain a further physical interpretation of the beam dynamics.

Poster WEPAB256 [1.162 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB256

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paper received ※ 19 May 2021 paper accepted ※ 21 July 2021 issue date ※ 13 August 2021

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WEPAB398

A C-Band RF Mode Launcher with Quadrupole Field Components Cancellation for High Brightness Applications

3638

G. Pedrocchi
SBAI, Roma, Italy
D. Alesini, F. Cardelli, A. Gallo, A. Giribono, B. Spataro
INFN/LNF, Frascati, Italy
G. Castorina
AVO-ADAM, Meyrin, Switzerland
L. Ficcadenti
INFN-Roma, Roma, Italy
M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy

The R&D of high gradient radiofrequency devices is aimed to develop innovative and compact accelerating stuctures based on new manufactoring techniques and materials in order to produce devices operating with the highest accelerating gradient. Recent studies have shown a large increase in the maximum sustained RF surface electric fields in copper structure operating at cryogenic temperature. These novel approaches allow significant performance improvements of RF photoinjectors. Indeed the operation at high surface fields results in considerable increase of electron brilliance. This requires high field quality in the RF photoinjector and specifically in its poweer coupler. In this work we present a novel power coupler for the RF photoinjector. The coupler is a compact C-band TM01 mode launcher with a fourfold symmetry which minimized both the dipole and the quadrupole RF field components.

Poster WEPAB398 [1.799 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB398

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paper received ※ 13 May 2021 paper accepted ※ 06 July 2021 issue date ※ 23 August 2021

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MOXC01

Combined Effect of Beam-Beam Interaction and Beam Coupling Impedance in Future Circular Colliders

25

Y. Zhang, N. Wang
IHEP, Beijing, People’s Republic of China
E. Carideo
CERN, Geneva, Switzerland
M. Migliorati
SBAI, Roma, Italy
M. Zobov
INFN/LNF, Frascati, Italy

Funding: This work is supported by National Key Programme for S&T Research and Development, China (Grant No. 2016YFA0400400), National Natural Science Foundation of China (No. 11775238, No. 11775239).
The future large scale electron-positron colliders, such as FCC-ee in Europe and CEPC in China, will rely on the crab waist collision scheme with a large Piwinski angle. Differently from the past generation colliders both luminosity and beam-beam tune shifts depend on the bunch length in such a collision scheme. In addition, for the future circular colliders with extreme beam parameters in collision several new effects become important such as beamstrahlung, coherent X-Z instability and 3D flip-flop. For all these effects the longitudinal beam dynamics plays an essential role and should be taken into account for the collider luminosity optimization. In this paper we discuss an impact of the longitudinal beam coupling impedance on the collider performance.

Slides MOXC01 [2.269 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXC01

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paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 17 August 2021

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