LINAC2018 - List of Keywords (space-charge)

Paper	Title	Other Keywords	Page
MOPO092	A 3-gap Booster Cavity to Match Ion Source Potential to RFQ Acceptance	booster, rfq, ISAC, bunching	196
	R.E. Laxdal, Z.T. Ang, T. Au, S. Kiy, S.D. Rädel, O. Shelbaya, V. Zvyagintsev TRIUMF, Vancouver, Canada
	The ISAC RFQ can accelerate ions with A/Q ration from 1 to 30 and requires an input energy of 2.04keV/u. The harsh environment of the ISAC on-line ISOL target facility makes it difficult to meet the energy for the heaviest masses. For these cases we have designed and installed a short three gap device that accelerates the beams produced at source potential to match the required energy for RFQ acceptance. The booster cavity operates at 11.7MHz, the RF frequency of the pre-buncher. The device can also be used as a second buncher to augment the acceptance in the RFQ or to improve the acceptance of higher space charge beams. The device will be described and the results of beam measurements will be given.
	Slides MOPO092 [7.627 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO092
About •	paper received ※ 14 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU1P01	Extreme High Brightness Electron Beam Generation in a Space Charge Regime	cavity, emittance, electron, bunching	314
	A. Bacci Istituto Nazionale di Fisica Nucleare, Milano, Italy L. Faillace, M. Rossetti Conti Universita’ degli Studi di Milano & INFN, Milano, Italy
	The generation of ultra-short, low emittance and low energy spread electron bunches is nowadays a critical requirement for accelerators in plasma wave or for femto-second light sources. A new longitudinal compression scheme, based on velocity and ballistic bunching tech-niques in presence of space charge forces, allows to enter in a peculiar regime, so-called laminar bunching (LB). In this regime, the bunch is longitudinally compressed, at the expense of its transverse size, and the over-bunching is forbidden by the laminarity: going to the minimal longi-tudinal dimension the bunch is adiabatically frozen and transversally refocused. Furthermore this technique heats slightly the uncorrelated energy spread resulting in elec-tron distributions that, in case of bending paths, does not require Laser Heater devices.
	Slides TU1P01 [1.720 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU1P01
About •	paper received ※ 12 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPO016	High Frequency RFQ Design and LEBT Matching for the CERN TwinEBIS Ion Source	rfq, emittance, gun, simulation	358
	V. Bencini, J.-B. Lallement, A.M. Lombardi, H. Pahl, J. Pitters, F.J.C. Wenander CERN, Geneva, Switzerland M. Breitenfeldt AVO-ADAM, Meyrin, Switzerland A.I. Pikin BNL, Upton, Long Island, New York, USA
	An Electron Beam Ion Source (EBIS) is being developed at CERN for production of highly charged ions, for instance fully stripped 12C. The focus has so far been on the electron gun design, aiming for a high current compression, which results in a rapid ionisation process and thereby high repetition rate. Initial commissioning tests of such an electron gun, the so-called MEDeGUN, have already been performed and we are now in the process of designing a multi-purpose ion extraction and diagnostics line. The Low Energy Beam Transport (LEBT) line will transport the ions into the downstream Radio Frequency Quadrupole (RFQ) with a nominal energy of 15 keV/u. The 750 MHz RFQ is designed to accelerate ions from 15 keV/u up to the final energy of 2.5 MeV/u. After the RFQ design was finalized and its acceptance calculated, the beam matching to the RFQ was studied, finding a set of parameters for the LEBT that maximize the transmission through the RFQ. Details of the RFQ design, of the LEBT matching procedure and its final results are illustrated in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO016
About •	paper received ※ 11 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPO098	Proof-of-Principle Tests for Slit-scan-based Slice Emittance Measurements at PITZ	emittance, electron, FEL, laser	553
	R. Niemczyk, P. Boonpornprasert, Y. Chen, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, C. Koschitzki, M. Krasilnikov, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, H.J. Qian, Y. Renier, C. Saisa-ard, F. Stephan, Q.T. Zhao DESY Zeuthen, Zeuthen, Germany W. Hillert University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Transverse slice emittance is one of the most important properties of high-brightness electron beams for freeelectron lasers (FELs). The photo injector test facility at DESY in Zeuthen (PITZ) develops high-brightness electron sources for modern FELs. With a 23 MeV, 1 nC beam at PITZ the experimental slice emittance characterization with the quadrupole scan technique is complicated by strong space charge effects. Combining the slit scan technique with a transverse deflecting cavity (TDS) allows for timeresolved emittance measurements of such a space-chargedominated beam. The first proof-of-principle results of slice emittance measurements at PITZ based on the ’TDS + slit scan’-technique are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO098
About •	paper received ※ 04 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPO009	Evaluation of 60pC Beam Performance at cERL Injector for ERL Based EUV-FEL	emittance, cavity, optics, electromagnetic-fields	699
	T. Hotei Sokendai, Ibaraki, Japan R. Kato, T. Miyajima KEK, Ibaraki, Japan
	In order to compensate for the emittance which is increased by space charge in the low energy region, it is important to transport the beam as designed. Until now, we did not consider couplers in injector superdonducting cavities in optics design. But in this study, to improve optics matching and emittance compensation conditions for space charge dominated beam in cERL at KEK, we introduced a new 3D cavity model. We first investigated the influence of the couplers on electromagnetic field distribution. As a result, it was found that an asymmetric focusing force is generated by the influence of the couplers. It also became clear that the influence of the coupler kick on the optics significantly devastated the emittance compensation condition from the calculating including space charge. Furthermore, it was found that by optimizing the optics in consideration of the coupler kick, it is possible to improve the beam control accuracy and reduce the emittance in beam commissioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO009
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPO116	Space-Charge Dominated Photoemission in High Gradient Photocathode RF Guns	cathode, laser, emittance, gun	941
	Y. Chen, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, C. Koschitzki, M. Krasilnikov, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, Y. Renier, F. Stephan DESY Zeuthen, Zeuthen, Germany H. Chen, Y. C. Du, W.-H. Huang, C.-X. Tang, Q.L. Tian, L.X. Yan TUB, Beijing, People’s Republic of China H. De Gersem, E. Gjonaj TEMF, TU Darmstadt, Darmstadt, Germany M. Dohlus DESY, Hamburg, Germany S. A. Schmid Institut Theorie Elektromagnetischer Felder, TU Darmstadt, Darmstadt, Germany
	The cathode emission physics plays a crucial role in the overall beam dynamics in the gun. Interplays between intricate emission mechanisms in the cathode vicinity strongly influence the cathode quantum efficiency (QE) and the intrinsic emittance. The presence of strong space-charge effects in high gradient RF guns further complicates the emission process. A proper modeling of photoemission and a careful treatment of the space-charge contribution is thus of great necessity to understanding the formation of the beam slice emittance. In this article, emission measurements are carried out using the L-band cesium-telluride photocathode RF gun at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) and the S-band copper photocathode RF gun at Tsinghua University. Following the Dowell model a simple so-called space-charge iteration approach is developed and used to determine the QE through temporal and spatial-dependent electromagnetic fields. An impact of the space-charge cooling on the thermal emittance is presented. Measurement data are shown and discussed in comparisons to preliminary simulation results.
	Slides THPO116 [6.249 MB]
	Poster THPO116 [3.157 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO116
About •	paper received ※ 11 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOPO092

A 3-gap Booster Cavity to Match Ion Source Potential to RFQ Acceptance

booster, rfq, ISAC, bunching

196

R.E. Laxdal, Z.T. Ang, T. Au, S. Kiy, S.D. Rädel, O. Shelbaya, V. Zvyagintsev
TRIUMF, Vancouver, Canada

The ISAC RFQ can accelerate ions with A/Q ration from 1 to 30 and requires an input energy of 2.04keV/u. The harsh environment of the ISAC on-line ISOL target facility makes it difficult to meet the energy for the heaviest masses. For these cases we have designed and installed a short three gap device that accelerates the beams produced at source potential to match the required energy for RFQ acceptance. The booster cavity operates at 11.7MHz, the RF frequency of the pre-buncher. The device can also be used as a second buncher to augment the acceptance in the RFQ or to improve the acceptance of higher space charge beams. The device will be described and the results of beam measurements will be given.

Slides MOPO092 [7.627 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO092

About •

paper received ※ 14 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU1P01

Extreme High Brightness Electron Beam Generation in a Space Charge Regime

cavity, emittance, electron, bunching

314

A. Bacci
Istituto Nazionale di Fisica Nucleare, Milano, Italy
L. Faillace, M. Rossetti Conti
Universita’ degli Studi di Milano & INFN, Milano, Italy

The generation of ultra-short, low emittance and low energy spread electron bunches is nowadays a critical requirement for accelerators in plasma wave or for femto-second light sources. A new longitudinal compression scheme, based on velocity and ballistic bunching tech-niques in presence of space charge forces, allows to enter in a peculiar regime, so-called laminar bunching (LB). In this regime, the bunch is longitudinally compressed, at the expense of its transverse size, and the over-bunching is forbidden by the laminarity: going to the minimal longi-tudinal dimension the bunch is adiabatically frozen and transversally refocused. Furthermore this technique heats slightly the uncorrelated energy spread resulting in elec-tron distributions that, in case of bending paths, does not require Laser Heater devices.

Slides TU1P01 [1.720 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TU1P01

About •

paper received ※ 12 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPO016

High Frequency RFQ Design and LEBT Matching for the CERN TwinEBIS Ion Source

rfq, emittance, gun, simulation

358

V. Bencini, J.-B. Lallement, A.M. Lombardi, H. Pahl, J. Pitters, F.J.C. Wenander
CERN, Geneva, Switzerland
M. Breitenfeldt
AVO-ADAM, Meyrin, Switzerland
A.I. Pikin
BNL, Upton, Long Island, New York, USA

An Electron Beam Ion Source (EBIS) is being developed at CERN for production of highly charged ions, for instance fully stripped 12C. The focus has so far been on the electron gun design, aiming for a high current compression, which results in a rapid ionisation process and thereby high repetition rate. Initial commissioning tests of such an electron gun, the so-called MEDeGUN, have already been performed and we are now in the process of designing a multi-purpose ion extraction and diagnostics line. The Low Energy Beam Transport (LEBT) line will transport the ions into the downstream Radio Frequency Quadrupole (RFQ) with a nominal energy of 15 keV/u. The 750 MHz RFQ is designed to accelerate ions from 15 keV/u up to the final energy of 2.5 MeV/u. After the RFQ design was finalized and its acceptance calculated, the beam matching to the RFQ was studied, finding a set of parameters for the LEBT that maximize the transmission through the RFQ. Details of the RFQ design, of the LEBT matching procedure and its final results are illustrated in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO016

About •

paper received ※ 11 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPO098

Proof-of-Principle Tests for Slit-scan-based Slice Emittance Measurements at PITZ

emittance, electron, FEL, laser

553

R. Niemczyk, P. Boonpornprasert, Y. Chen, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, C. Koschitzki, M. Krasilnikov, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, H.J. Qian, Y. Renier, C. Saisa-ard, F. Stephan, Q.T. Zhao
DESY Zeuthen, Zeuthen, Germany
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Transverse slice emittance is one of the most important properties of high-brightness electron beams for freeelectron lasers (FELs). The photo injector test facility at DESY in Zeuthen (PITZ) develops high-brightness electron sources for modern FELs. With a 23 MeV, 1 nC beam at PITZ the experimental slice emittance characterization with the quadrupole scan technique is complicated by strong space charge effects. Combining the slit scan technique with a transverse deflecting cavity (TDS) allows for timeresolved emittance measurements of such a space-chargedominated beam. The first proof-of-principle results of slice emittance measurements at PITZ based on the ’TDS + slit scan’-technique are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO098

About •

paper received ※ 04 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPO009

Evaluation of 60pC Beam Performance at cERL Injector for ERL Based EUV-FEL

emittance, cavity, optics, electromagnetic-fields

699

T. Hotei
Sokendai, Ibaraki, Japan
R. Kato, T. Miyajima
KEK, Ibaraki, Japan

In order to compensate for the emittance which is increased by space charge in the low energy region, it is important to transport the beam as designed. Until now, we did not consider couplers in injector superdonducting cavities in optics design. But in this study, to improve optics matching and emittance compensation conditions for space charge dominated beam in cERL at KEK, we introduced a new 3D cavity model. We first investigated the influence of the couplers on electromagnetic field distribution. As a result, it was found that an asymmetric focusing force is generated by the influence of the couplers. It also became clear that the influence of the coupler kick on the optics significantly devastated the emittance compensation condition from the calculating including space charge. Furthermore, it was found that by optimizing the optics in consideration of the coupler kick, it is possible to improve the beam control accuracy and reduce the emittance in beam commissioning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO009

About •

paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPO116

Space-Charge Dominated Photoemission in High Gradient Photocathode RF Guns

cathode, laser, emittance, gun

941

Y. Chen, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, C. Koschitzki, M. Krasilnikov, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, Y. Renier, F. Stephan
DESY Zeuthen, Zeuthen, Germany
H. Chen, Y. C. Du, W.-H. Huang, C.-X. Tang, Q.L. Tian, L.X. Yan
TUB, Beijing, People’s Republic of China
H. De Gersem, E. Gjonaj
TEMF, TU Darmstadt, Darmstadt, Germany
M. Dohlus
DESY, Hamburg, Germany
S. A. Schmid
Institut Theorie Elektromagnetischer Felder, TU Darmstadt, Darmstadt, Germany

The cathode emission physics plays a crucial role in the overall beam dynamics in the gun. Interplays between intricate emission mechanisms in the cathode vicinity strongly influence the cathode quantum efficiency (QE) and the intrinsic emittance. The presence of strong space-charge effects in high gradient RF guns further complicates the emission process. A proper modeling of photoemission and a careful treatment of the space-charge contribution is thus of great necessity to understanding the formation of the beam slice emittance. In this article, emission measurements are carried out using the L-band cesium-telluride photocathode RF gun at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) and the S-band copper photocathode RF gun at Tsinghua University. Following the Dowell model a simple so-called space-charge iteration approach is developed and used to determine the QE through temporal and spatial-dependent electromagnetic fields. An impact of the space-charge cooling on the thermal emittance is presented. Measurement data are shown and discussed in comparisons to preliminary simulation results.

Slides THPO116 [6.249 MB]

Poster THPO116 [3.157 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO116

About •

paper received ※ 11 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)