NAPAC2016 - List of Authors (Venturini, M.)

Paper	Title	Page
TUB1CO03	ALS-U: A Soft X-Ray Diffraction Limited Light Source	263
	C. Steier, A. Anders, J.M. Byrd, K. Chow, S. De Santis, R.M. Duarte, J.-Y. Jung, T.H. Luo, H. Nishimura, T. Oliver, J.R. Osborn, H.A. Padmore, G.C. Pappas, S. Persichelli, D. Robin, F. Sannibale, D. Schlueter, C. Sun, C.A. Swenson, M. Venturini, W.L. Waldron, E.J. Wallén, W. Wan, Y.C. Yang LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Improvements in brightness and coherent flux of about two orders of magnitude over operational storage ring based light sources are possible using multi bend achromat lattice designs. These improvements can be implemented as upgrades of existing facilities, like the proposed upgrade of the Advanced Light Source (ALS-U). The upgrade proposal will reuse much of the existing infrastructure, thereby reducing cost and time needed to reach full scientific productivity on a large number of beamlines. We will report on the accelerator design progress as well as the details of the ongoing R+D program.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUB1CO03
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THPOA32	Sensitivity of the Microbunching Instability to Irregularities in Cathode Current in the LCLS-II Beam Delivery System	1171
	C.E. Mitchell, J. Qiang, M. Venturini LBNL, Berkeley, California, USA P. Emma SLAC, Menlo Park, California, USA
	Funding: This work is supported by the Office of Science of the U.S. Department of Energy under Contract Numbers DE-AC02-76SF00515, DE-AC02-05CH11231, and the LCLS-II Project. LCLS-II is a high-repetition rate (1 MHz) Free Electron Laser (FEL) X-ray light source now under construction at SLAC National Accelerator Laboratory. During transport to the FEL undulators, the electron beam is subject to a space charge-driven microbunching instability that can degrade the electron beam quality and lower the FEL performance if left uncontrolled. The present LCLS-II design is well-optimized to control the growth of this instability out of the electron beam shot noise. However, the instability may also be seeded by irregularities in the beam current profile at the cathode (due to non-uniformities in the temporal profile of the photogun drive laser pulse). In this paper, we describe the sensitivity of the microbunching instability to small-amplitude temporal modulations on the emitted beam current profile at the cathode, using high-resolution simulations of the LCLS-II beam delivery system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA32
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THPOA33	A Preliminary Beam Impedance Model of the Advanced Light Source Upgrade at LBL	1174
	S. Persichelli, J.M. Byrd, S. De Santis, D. Li, T.H. Luo, J.R. Osborn, C.A. Swenson, M. Venturini, Y. Yang LBNL, Berkeley, California, USA
	The proposed upgrade of the Advanced Light Source (ALS-U) consists of a multi-bend achromat ultralow emittance lattice optimized for the production of diffraction-limited soft x-rays. A narrow-aperture vacuum chamber is a key feature of the new generation of light sources, and can result in a significant increase in the beam impedance, potentially limiting the maximum achievable beam current. While the conceptual design of the vacuum system is still in a very early development stage, this paper presents a preliminary estimate of the beam impedance using a combination of electromagnetic simulations and analytical calculations. We include the impedance of cavities, select vacuum-chamber components and resistive wall in a multi-layered beam chamber with NEG coating.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA33
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Paper

Title

Page

ALS-U: A Soft X-Ray Diffraction Limited Light Source

263

C. Steier, A. Anders, J.M. Byrd, K. Chow, S. De Santis, R.M. Duarte, J.-Y. Jung, T.H. Luo, H. Nishimura, T. Oliver, J.R. Osborn, H.A. Padmore, G.C. Pappas, S. Persichelli, D. Robin, F. Sannibale, D. Schlueter, C. Sun, C.A. Swenson, M. Venturini, W.L. Waldron, E.J. Wallén, W. Wan, Y.C. Yang
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Improvements in brightness and coherent flux of about two orders of magnitude over operational storage ring based light sources are possible using multi bend achromat lattice designs. These improvements can be implemented as upgrades of existing facilities, like the proposed upgrade of the Advanced Light Source (ALS-U). The upgrade proposal will reuse much of the existing infrastructure, thereby reducing cost and time needed to reach full scientific productivity on a large number of beamlines. We will report on the accelerator design progress as well as the details of the ongoing R+D program.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUB1CO03

Export •

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

THPOA32

Sensitivity of the Microbunching Instability to Irregularities in Cathode Current in the LCLS-II Beam Delivery System

1171

C.E. Mitchell, J. Qiang, M. Venturini
LBNL, Berkeley, California, USA
P. Emma
SLAC, Menlo Park, California, USA

Funding: This work is supported by the Office of Science of the U.S. Department of Energy under Contract Numbers DE-AC02-76SF00515, DE-AC02-05CH11231, and the LCLS-II Project.
LCLS-II is a high-repetition rate (1 MHz) Free Electron Laser (FEL) X-ray light source now under construction at SLAC National Accelerator Laboratory. During transport to the FEL undulators, the electron beam is subject to a space charge-driven microbunching instability that can degrade the electron beam quality and lower the FEL performance if left uncontrolled. The present LCLS-II design is well-optimized to control the growth of this instability out of the electron beam shot noise. However, the instability may also be seeded by irregularities in the beam current profile at the cathode (due to non-uniformities in the temporal profile of the photogun drive laser pulse). In this paper, we describe the sensitivity of the microbunching instability to small-amplitude temporal modulations on the emitted beam current profile at the cathode, using high-resolution simulations of the LCLS-II beam delivery system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA32

Export •

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

THPOA33

A Preliminary Beam Impedance Model of the Advanced Light Source Upgrade at LBL

1174

S. Persichelli, J.M. Byrd, S. De Santis, D. Li, T.H. Luo, J.R. Osborn, C.A. Swenson, M. Venturini, Y. Yang
LBNL, Berkeley, California, USA

The proposed upgrade of the Advanced Light Source (ALS-U) consists of a multi-bend achromat ultralow emittance lattice optimized for the production of diffraction-limited soft x-rays. A narrow-aperture vacuum chamber is a key feature of the new generation of light sources, and can result in a significant increase in the beam impedance, potentially limiting the maximum achievable beam current. While the conceptual design of the vacuum system is still in a very early development stage, this paper presents a preliminary estimate of the beam impedance using a combination of electromagnetic simulations and analytical calculations. We include the impedance of cavities, select vacuum-chamber components and resistive wall in a multi-layered beam chamber with NEG coating.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA33

Export •

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