ICAP2018 - List of Keywords (gun)

Paper	Title	Other Keywords	Page
SAPAF03	Comparison of Model-Based and Heuristic Optimization Algorithms Applied to Photoinjectors Using Libensemble	simulation, cavity, space-charge, solenoid	22
	N.R. Neveu IIT, Chicago, Illinois, USA S. T. P. Hudson, J.M. Larson ANL, Argonne, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: U.S. DOE, OS, contract DE-AC02-06CH11357 and grant DE-SC0015479. Genetic algorithms are common and often used in the accelerator community. They require large amounts of computational resources and empirical adjustment of hyperparameters. Model based methods are significantly more efficient, but often labeled as unreliable for the nonlinear or unsmooth problems that can be found in accelerator physics. We investigate the behavior of both approaches using a photoinjector operated in the space charge dominated regime. All optimization runs are coordinated and managed by the Python library libEnsemble, which is developed at Argonne National Laboratory.
	Slides SAPAF03 [0.653 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SAPAF03
About •	paper received ※ 11 November 2018 paper accepted ※ 19 November 2018 issue date ※ 26 January 2019
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TUPAF19	pyaopt Optimization Suite and its Applications to an SRF Cavity Design for UEMs	SRF, simulation, cavity, electron	229
	A. Liu, P.V. Avrakhov, R.A. Kostin Euclid TechLabs, LLC, Solon, Ohio, USA C.-J. Jing Euclid Beamlabs LLC, Bolingbrook, USA
	Funding: DOE SBIR In order to achieve sharp, high resolution real-time imaging, electrons in a MeV UEM (ultrafast electron microscope) beamline need to minimize instabilities. The Superconducting RF (SRF) photocathode gun is a promising candidate to produce highly stable electrons for UEM/UED applications. It operates in an ultrahigh Q, CW mode, and dissipates a few watts of RF power, which make it possible to achieve a 10s ppm level of beam stability by using modern RF control techniques. In order to find the best performance of the gun design, an optimization procedure is required. pyaopt is a Python-based optimization suite that supports multi-objective optimizations using advanced algorithms. In this paper, the novel SRF photogun design and its optimizations through pyaopt and Astra’s beam simulations will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF19
About •	paper received ※ 22 October 2018 paper accepted ※ 15 December 2018 issue date ※ 26 January 2019
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TUPAG13	S-Based Macro-Particle Spectral Algorithm for an Electron Gun	electron, cathode, solenoid, simulation	290
	P. M. Jung, T. Planche TRIUMF, Vancouver, Canada
	We derive a Hamiltonian description of a continuous particle distribution and its electrostatic potential from the Low Lagrangian. The self consistent space charge potential is discretized according to the spectral Galerkin approximation. The particle distribution is discretized using macro-particles. We choose a set of initial and boundary conditions to model the TRIUMF 300keV thermionic DC electron gun. The field modes and macro-particle coordinates are integrated self-consistently. The current status of the implementation is discussed.
	Slides TUPAG13 [1.335 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG13
About •	paper received ※ 01 November 2018 paper accepted ※ 10 December 2018 issue date ※ 26 January 2019
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WEPAF02	Simulations of Beam Chopping for Potential Upgrades of the SNS LEBT Chopper	rfq, simulation, LEBT, operation	325
	B. Han, S.N. Murray, T.R. Pennisi, V.V. Peplov, M.P. Stockli, R.F. Welton ORNL, Oak Ridge, Tennessee, USA R.B. Saethre, C. Stinson ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work was performed at Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, under contract number DE-AC05-00OR22725 for the United States Department of Energy. The LEBT chopper is a critical element of the SNS accelerator system. In this work, the benefit of increasing the chopping voltage amplitude for the present chopping pattern is shown with beam simulations, and an ongoing hardware upgrade of the chopper pulser units is discussed. In addition, with the prospect of higher voltage capability of the new pulser design, two alternative chopping patterns which reduce the switching frequency of the chopper pulsers down to 1/2 or 1/4 of the present chopping pattern, are also explored with beam simulations.
	Slides WEPAF02 [7.431 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPAF02
About •	paper received ※ 31 October 2018 paper accepted ※ 07 December 2018 issue date ※ 26 January 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

SAPAF03

Comparison of Model-Based and Heuristic Optimization Algorithms Applied to Photoinjectors Using Libensemble

simulation, cavity, space-charge, solenoid

22

N.R. Neveu
IIT, Chicago, Illinois, USA
S. T. P. Hudson, J.M. Larson
ANL, Argonne, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: U.S. DOE, OS, contract DE-AC02-06CH11357 and grant DE-SC0015479.
Genetic algorithms are common and often used in the accelerator community. They require large amounts of computational resources and empirical adjustment of hyperparameters. Model based methods are significantly more efficient, but often labeled as unreliable for the nonlinear or unsmooth problems that can be found in accelerator physics. We investigate the behavior of both approaches using a photoinjector operated in the space charge dominated regime. All optimization runs are coordinated and managed by the Python library libEnsemble, which is developed at Argonne National Laboratory.

Slides SAPAF03 [0.653 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SAPAF03

About •

paper received ※ 11 November 2018 paper accepted ※ 19 November 2018 issue date ※ 26 January 2019

Export •

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

TUPAF19

pyaopt Optimization Suite and its Applications to an SRF Cavity Design for UEMs

SRF, simulation, cavity, electron

229

A. Liu, P.V. Avrakhov, R.A. Kostin
Euclid TechLabs, LLC, Solon, Ohio, USA
C.-J. Jing
Euclid Beamlabs LLC, Bolingbrook, USA

Funding: DOE SBIR
In order to achieve sharp, high resolution real-time imaging, electrons in a MeV UEM (ultrafast electron microscope) beamline need to minimize instabilities. The Superconducting RF (SRF) photocathode gun is a promising candidate to produce highly stable electrons for UEM/UED applications. It operates in an ultrahigh Q, CW mode, and dissipates a few watts of RF power, which make it possible to achieve a 10s ppm level of beam stability by using modern RF control techniques. In order to find the best performance of the gun design, an optimization procedure is required. pyaopt is a Python-based optimization suite that supports multi-objective optimizations using advanced algorithms. In this paper, the novel SRF photogun design and its optimizations through pyaopt and Astra’s beam simulations will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF19

About •

paper received ※ 22 October 2018 paper accepted ※ 15 December 2018 issue date ※ 26 January 2019

Export •

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

TUPAG13

S-Based Macro-Particle Spectral Algorithm for an Electron Gun

electron, cathode, solenoid, simulation

290

P. M. Jung, T. Planche
TRIUMF, Vancouver, Canada

We derive a Hamiltonian description of a continuous particle distribution and its electrostatic potential from the Low Lagrangian. The self consistent space charge potential is discretized according to the spectral Galerkin approximation. The particle distribution is discretized using macro-particles. We choose a set of initial and boundary conditions to model the TRIUMF 300keV thermionic DC electron gun. The field modes and macro-particle coordinates are integrated self-consistently. The current status of the implementation is discussed.

Slides TUPAG13 [1.335 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG13

About •

paper received ※ 01 November 2018 paper accepted ※ 10 December 2018 issue date ※ 26 January 2019

Export •

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

WEPAF02

Simulations of Beam Chopping for Potential Upgrades of the SNS LEBT Chopper

rfq, simulation, LEBT, operation

325

B. Han, S.N. Murray, T.R. Pennisi, V.V. Peplov, M.P. Stockli, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA
R.B. Saethre, C. Stinson
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work was performed at Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, under contract number DE-AC05-00OR22725 for the United States Department of Energy.
The LEBT chopper is a critical element of the SNS accelerator system. In this work, the benefit of increasing the chopping voltage amplitude for the present chopping pattern is shown with beam simulations, and an ongoing hardware upgrade of the chopper pulser units is discussed. In addition, with the prospect of higher voltage capability of the new pulser design, two alternative chopping patterns which reduce the switching frequency of the chopper pulsers down to 1/2 or 1/4 of the present chopping pattern, are also explored with beam simulations.

Slides WEPAF02 [7.431 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPAF02

About •

paper received ※ 31 October 2018 paper accepted ※ 07 December 2018 issue date ※ 26 January 2019

Export •

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