NAPAC2016 - List of Authors (Qiang, J.)

Paper	Title	Page
TUPOB62	Benchmark of Strong-Strong Beam-Beam Simulation of the Kink Instability in an Electron Ion Collider Design	628
	J. Qiang, R.D. Ryne LBNL, Berkeley, California, USA Y. Hao BNL, Upton, Long Island, New York, USA
	The kink instability limits the performance of a potential linac-ring based electron-ion collider design. In this paper, we report on the simulation study of the kink instability using a self-consistent strong-strong beam-beam model.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB62
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WEPOA28	A Recirculating Proton Linac Design	752
	K. Hwang, J. Qiang LBNL, Berkeley, California, USA
	The acceleration efficiency of the recirculating RF linac was demonstrated by operating electron machines. The acceleration concept of recirculating proton beam was recently proposed and is currently under study. In this paper, we present a 6D lattice design and beam dynamics tracking for a two-pass recirculating proton linac from 150 MeV to 500 MeV, which is the first section of the three acceleration steps proposed earlier. Issues covered are optimization of simultaneous focusing of two beams passing the same structure and achromatic condition under space-charge potential.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA28
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WEA3IO02	Start-to-End Beam Dynamics Optimization of X-Ray FEL Light Source Accelerators	838
	J. Qiang LBNL, Berkeley, California, USA
	State-of-the-art tools have been developed that allow start-to-end modeling of the beam formation at the cathode, to its transport, acceleration, and delivery to the undulator. Algorithms are based on first principles, enabling the capture of detailed physics such as shot-noise driven micro-bunching instabilities. The most recent generation of the IMPACT code, using multi-level parallelization on massively parallel supercomputers, now enables multi-objective parametric optimization. This is facilitated by recent advances such as the unified differential evolution algorithm. The most recent developments will be described, together with applications to the modeling of LCLS-II. J. Qiang, et al, http://www.optimization-online.org/DB_FILE/2015/03/4796.pdf, submitted **J. Qiang, et al, in preparation
	Slides WEA3IO02 [10.928 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA3IO02
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WEPOB29	Modeling of Dark Current Generation and Transport Using the IMPACT-T Code	964
	J. Qiang, K. Hwang LBNL, Berkeley, California, USA
	Dark current from unwanted electrons in photoinjector can present significant danger to the accelerator operation by causing damage to photocathode and power deposition onto conducting wall. In this paper, we present numerical models of dark current generation from the field emission and from the electron impact ionization of the residual gas that were recently developed in the IMPACT-T code. We also report on the application of above numerical model to an LCLS-II like photoinjector.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB29
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WEPOB30	Simulation of the Shot-Noise Driven Microbunching Instability Experiment at the LCLS	967
	J. Qiang LBNL, Berkeley, California, USA Y. Ding, P. Emma, Z. Huang, D.F. Ratner, T.O. Raubenheimer, F. Zhou SLAC, Menlo Park, California, USA
	The shot-noise driven microbunching instability can significantly degrade electron beam quality in next generation light sources. Experiments were carried out at the Linac Coherent Light Source (LCLS) to study this instability. In this paper, we will present start-to-end simulation of the shot-noise driven microbunching instability experiment at the LCLS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB30
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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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Paper

Title

Page

Benchmark of Strong-Strong Beam-Beam Simulation of the Kink Instability in an Electron Ion Collider Design

628

J. Qiang, R.D. Ryne
LBNL, Berkeley, California, USA
Y. Hao
BNL, Upton, Long Island, New York, USA

The kink instability limits the performance of a potential linac-ring based electron-ion collider design. In this paper, we report on the simulation study of the kink instability using a self-consistent strong-strong beam-beam model.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB62

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WEPOA28

A Recirculating Proton Linac Design

752

K. Hwang, J. Qiang
LBNL, Berkeley, California, USA

The acceleration efficiency of the recirculating RF linac was demonstrated by operating electron machines. The acceleration concept of recirculating proton beam was recently proposed and is currently under study. In this paper, we present a 6D lattice design and beam dynamics tracking for a two-pass recirculating proton linac from 150 MeV to 500 MeV, which is the first section of the three acceleration steps proposed earlier. Issues covered are optimization of simultaneous focusing of two beams passing the same structure and achromatic condition under space-charge potential.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA28

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WEA3IO02

Start-to-End Beam Dynamics Optimization of X-Ray FEL Light Source Accelerators

838

J. Qiang
LBNL, Berkeley, California, USA

State-of-the-art tools have been developed that allow start-to-end modeling of the beam formation at the cathode, to its transport, acceleration, and delivery to the undulator. Algorithms are based on first principles, enabling the capture of detailed physics such as shot-noise driven micro-bunching instabilities. The most recent generation of the IMPACT code, using multi-level parallelization on massively parallel supercomputers, now enables multi-objective parametric optimization. This is facilitated by recent advances such as the unified differential evolution algorithm*. The most recent developments will be described, together with applications to the modeling of LCLS-II**.
*J. Qiang, et al, http://www.optimization-online.org/DB_FILE/2015/03/4796.pdf, submitted
**J. Qiang, et al, in preparation

Slides WEA3IO02 [10.928 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA3IO02

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WEPOB29

Modeling of Dark Current Generation and Transport Using the IMPACT-T Code

964

J. Qiang, K. Hwang
LBNL, Berkeley, California, USA

Dark current from unwanted electrons in photoinjector can present significant danger to the accelerator operation by causing damage to photocathode and power deposition onto conducting wall. In this paper, we present numerical models of dark current generation from the field emission and from the electron impact ionization of the residual gas that were recently developed in the IMPACT-T code. We also report on the application of above numerical model to an LCLS-II like photoinjector.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB29

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WEPOB30

Simulation of the Shot-Noise Driven Microbunching Instability Experiment at the LCLS

967

J. Qiang
LBNL, Berkeley, California, USA
Y. Ding, P. Emma, Z. Huang, D.F. Ratner, T.O. Raubenheimer, F. Zhou
SLAC, Menlo Park, California, USA

The shot-noise driven microbunching instability can significantly degrade electron beam quality in next generation light sources. Experiments were carried out at the Linac Coherent Light Source (LCLS) to study this instability. In this paper, we will present start-to-end simulation of the shot-noise driven microbunching instability experiment at the LCLS.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB30

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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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