LINAC2016 - List of Keywords (beam-loading)

Paper	Title	Other Keywords	Page
MOP106016	High Power RF Requirements for Driving Discontinuous Bunch Trains in the MaRIE Linac	linac, cavity, electron, booster	320
	J.T. Bradley III, D. Rees, A. Scheinker, R.L. Sheffield LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the US Department of Energy. The MaRIE project will use a superconducting linac to provide 12 GeV electron bunches to drive an X-ray FEL and to do electron radiography. Dynamic experiments planned for MaRIE require that the linac produce a series of micropulses that can be irregularly spaced within the macropulse, and these patterns can change from macropulse to macropulse. Irregular pulse structures create a challenge to optimizing the design of the RF and cryogenic systems. General formulas for cavities with beam loading can overestimate the power required for our irregular beam macropulse. The differing beam energy variations allowed for the XFEL and eRad micropulses produce cavity voltage control requirements that also vary within the macropulse. The RF pulse driving the cavities can be tailored to meet the needs of that particular beam macropulse because the macropulse structure is known before the pulse starts. We will derive a toolkit that can be used to determine the required RF power waveforms for arbitrary macropulse structures. We will also examine how the irregular RF power waveforms can impact RF and cryogenic system cost tradeoffs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106016
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU2A04	High-Gradient RF Development and Applications	klystron, linac, collider, damping	368
	W. Wuensch CERN, Geneva, Switzerland
	Significant progress has been made by the CLIC collaboration to understand the phenomena which limit gradient in normal-conducting accelerating structures and to increase achievable gradient in excess of 100 MV/m. Scientific and technological highlights from the CLIC high-gradient program are presented along with on-going developments and future plans. The talk will also give an overview of the range of applications that potentially benefit from high-frequency and high-gradient accelerating technology.
	Slides TU2A04 [14.317 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TU2A04
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPRC008	Electron Driven ILC Positron Source with a Low Gradient Capture Linac	positron, electron, linac, simulation	430
	M. Kuriki HU/AdSM, Higashi-Hiroshima, Japan T. Kakita Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan S. Kashiwagi Tohoku University, School of Science, Sendai, Japan K. Negishi Iwate University, Morioka, Iwate, Japan T. Okugi, T. Omori, M. Satoh, Y. Seimiya, J. Urakawa, K. Yokoya KEK, Ibaraki, Japan T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
	ILC (International Linear Collider) is e⁺ e⁻ linear collider in the next high energy program promoted by ICFA. In ILC, an intense positron pulse in a multi-bunch format is generated with gamma ray from Undulator radiation. As a technical backup, the electron driven positron source has been studied. By employing a standing wave L-band accelerator for the capture linac, an enough amount of positron can be captured due to the large aperture, even with a limited accelerator gradient. However, the heavy beam loading up to 2 A perturbs the field gradient and profile along the longitudinal position. We present the capture performance of the ILC positron source including the heavy beam loading effect.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC008
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPLR009	An Iterative Learning Feedforward Controller for the TRIUMF e-linac	cavity, linac, TRIUMF, controls	485
	M.P. Laverty, K. Fong TRIUMF, Vancouver, Canada
	In the TRIUMF e-linac design, beam stability to within 0.1% within 10 μs in pulse mode is a design requirement. Traditional feedback control systems cannot respond within this time frame, so some form of feedforward control is needed. Even conventional feedforward may not be sufficient due to differences between the required feedforward signal and the actual beam-loading current. For this reason, an adaptive feedforward system using an iterative learning controller was developed for the e-linac LLRF. It can anticipate repetitive beam disturbance patterns by learning from previous iterations. The design and implementation of such a control algorithm is outlined, some simulation results are presented, and some preliminary test results with an actual cavity are illustrated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR009
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPLR012	Beam-Loading Compensation of a Multi-Bunch Electron Beam by Using RF Amplitude Modulation in Laser Undulator Compact X-Ray Source (LUCX)	gun, laser, electron, cavity	867
	M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan M. Washio Waseda University, Tokyo, Japan
	Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. We have been developing a compact X-ray source via laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. In here, a multi-bunch electron beam is generated by a 3.6cell photo-cathode RF-gun and accelerated to 18-24MeV by a 12cell booster. And then 6-10 keV X-rays are generated by LCS between the beam and a laser pulse stored in a 4-mirror planar optical cavity. Our aim is to take a phase contrast image with Talbot interferometer within a few minutes at present. The target flux of X-ray is 1.7x10⁷ photons/pulse with 10% bandwidth. For an electron beam, the target of the intensity is 500nC/pulse with 1000 bunches at 30 MeV. Presently, we have achieved the generation of 24MeV beam with total charge of 600nC in 1000bunches. The energy difference is within 1.3% peak to peak. The beam-loading is compensated by delta T method and amplitude modulation(AM) of the RF pulse. However there is the energy difference at the RF-gun. It is assumed that this causes the reduction of the X-ray flux due to change of the focused beam size. To reduce the energy difference, AM is also applied to the RF pulse for the gun. We will show the results of the beam-loading compensation and the generation of X-rays. Y. Yokoyama et al. , Proceedings IPAC2011, TUPC059 (2011).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOP106016

High Power RF Requirements for Driving Discontinuous Bunch Trains in the MaRIE Linac

linac, cavity, electron, booster

320

J.T. Bradley III, D. Rees, A. Scheinker, R.L. Sheffield
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the US Department of Energy.
The MaRIE project will use a superconducting linac to provide 12 GeV electron bunches to drive an X-ray FEL and to do electron radiography. Dynamic experiments planned for MaRIE require that the linac produce a series of micropulses that can be irregularly spaced within the macropulse, and these patterns can change from macropulse to macropulse. Irregular pulse structures create a challenge to optimizing the design of the RF and cryogenic systems. General formulas for cavities with beam loading can overestimate the power required for our irregular beam macropulse. The differing beam energy variations allowed for the XFEL and eRad micropulses produce cavity voltage control requirements that also vary within the macropulse. The RF pulse driving the cavities can be tailored to meet the needs of that particular beam macropulse because the macropulse structure is known before the pulse starts. We will derive a toolkit that can be used to determine the required RF power waveforms for arbitrary macropulse structures. We will also examine how the irregular RF power waveforms can impact RF and cryogenic system cost tradeoffs.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106016

Export •

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

TU2A04

High-Gradient RF Development and Applications

klystron, linac, collider, damping

368

W. Wuensch
CERN, Geneva, Switzerland

Significant progress has been made by the CLIC collaboration to understand the phenomena which limit gradient in normal-conducting accelerating structures and to increase achievable gradient in excess of 100 MV/m. Scientific and technological highlights from the CLIC high-gradient program are presented along with on-going developments and future plans. The talk will also give an overview of the range of applications that potentially benefit from high-frequency and high-gradient accelerating technology.

Slides TU2A04 [14.317 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TU2A04

Export •

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

TUPRC008

Electron Driven ILC Positron Source with a Low Gradient Capture Linac

positron, electron, linac, simulation

430

M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
T. Kakita
Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan
S. Kashiwagi
Tohoku University, School of Science, Sendai, Japan
K. Negishi
Iwate University, Morioka, Iwate, Japan
T. Okugi, T. Omori, M. Satoh, Y. Seimiya, J. Urakawa, K. Yokoya
KEK, Ibaraki, Japan
T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

ILC (International Linear Collider) is e⁺ e⁻ linear collider in the next high energy program promoted by ICFA. In ILC, an intense positron pulse in a multi-bunch format is generated with gamma ray from Undulator radiation. As a technical backup, the electron driven positron source has been studied. By employing a standing wave L-band accelerator for the capture linac, an enough amount of positron can be captured due to the large aperture, even with a limited accelerator gradient. However, the heavy beam loading up to 2 A perturbs the field gradient and profile along the longitudinal position. We present the capture performance of the ILC positron source including the heavy beam loading effect.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC008

Export •

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

TUPLR009

An Iterative Learning Feedforward Controller for the TRIUMF e-linac

cavity, linac, TRIUMF, controls

485

M.P. Laverty, K. Fong
TRIUMF, Vancouver, Canada

In the TRIUMF e-linac design, beam stability to within 0.1% within 10 μs in pulse mode is a design requirement. Traditional feedback control systems cannot respond within this time frame, so some form of feedforward control is needed. Even conventional feedforward may not be sufficient due to differences between the required feedforward signal and the actual beam-loading current. For this reason, an adaptive feedforward system using an iterative learning controller was developed for the e-linac LLRF. It can anticipate repetitive beam disturbance patterns by learning from previous iterations. The design and implementation of such a control algorithm is outlined, some simulation results are presented, and some preliminary test results with an actual cavity are illustrated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR009

Export •

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

THPLR012

Beam-Loading Compensation of a Multi-Bunch Electron Beam by Using RF Amplitude Modulation in Laser Undulator Compact X-Ray Source (LUCX)

gun, laser, electron, cavity

867

M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Washio
Waseda University, Tokyo, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have been developing a compact X-ray source via laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. In here, a multi-bunch electron beam is generated by a 3.6cell photo-cathode RF-gun and accelerated to 18-24MeV by a 12cell booster. And then 6-10 keV X-rays are generated by LCS between the beam and a laser pulse stored in a 4-mirror planar optical cavity. Our aim is to take a phase contrast image with Talbot interferometer within a few minutes at present. The target flux of X-ray is 1.7x10⁷ photons/pulse with 10% bandwidth. For an electron beam, the target of the intensity is 500nC/pulse with 1000 bunches at 30 MeV. Presently, we have achieved the generation of 24MeV beam with total charge of 600nC in 1000bunches. The energy difference is within 1.3% peak to peak. The beam-loading is compensated by delta T method and amplitude modulation(AM) of the RF pulse*. However there is the energy difference at the RF-gun. It is assumed that this causes the reduction of the X-ray flux due to change of the focused beam size. To reduce the energy difference, AM is also applied to the RF pulse for the gun. We will show the results of the beam-loading compensation and the generation of X-rays.
* Y. Yokoyama et al. , Proceedings IPAC2011, TUPC059 (2011).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR012

Export •

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