NAPAC2016 - List of Authors (Edelen, J.P.)

Paper	Title	Page
MOPOB17	Resonant Frequency Control for the PIP-II Injector Test RFQ: Control Framework and Initial Results	109
	A.L. Edelen, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA D.L. Bowring, B.E. Chase, J.P. Edelen, D.J. Nicklaus, J. Steimel Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359. For the PIP-II Injector Test (PI-Test) at Fermilab, a four-vane radio frequency quadrupole (RFQ) is designed to accelerate a 30-keV, 1-mA to 10-mA H' beam to 2.1 MeV under both pulsed and continuous wave (CW) RF operation. The available headroom of the RF amplifiers limit the maximum allowable detuning to 3 kHz, and the detuning is controlled entirely via thermal regulation. Fine control over the detuning, minimal manual intervention, and fast trip recovery is desired. In addition, having active control over both the walls and vanes provides a wider tuning range. For this, we intend to use model predictive control (MPC). To facilitate these objectives, we developed a dedicated control framework that handles higher-level system decisions as well as executes control calculations. It is written in Python in a modular fashion for easy adjustments, readability, and portability. Here we describe the framework and present the first control results for the PI-Test RFQ under pulsed and CW operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB17
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TUPOA18	Low Level RF Control for the PIP-II Injector Test RFQ	323
	J.P. Edelen, B.E. Chase, E. Cullerton, J. Einstein, P. Varghese Fermilab, Batavia, Illinois, USA
	The PIP-II injector test radio frequency quadrupole (RFQ) arrived at Fermilab in the fall of 2015. The RFQ is a 162.5MHz H⁻ accelerator with a nominal drive power of 100kW, which produces a bunched H⁻ beam at 2.1MeV. In this paper we discuss commissioning, operational performance, and improvements to the low level RF (LLRF) control system for the RFQ. We begin by describing the general system configuration and initial simulation results. We will then highlight temperature related issues in the high power RF system, which necessitate active control over the phase balance of the two amplifiers. Finally we demonstrate performance of the RF feedback and feed-forward compensation needed to meet specification during a 20-microsecond beam pulse.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA18
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TUPOA51	First Steps Toward Incorporating Image Based Diagnostics into Particle Accelerator Control Systems Using Convolutional Neural Networks	390
SUPO10	use link to see paper's listing under its alternate paper code
	A.L. Edelen, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA J.P. Edelen Fermilab, Batavia, Illinois, USA
	At present, a variety of image-based diagnostics are used in particle accelerator systems. Often times, these are viewed by a human operator who then makes appropriate adjustments to the machine. Given recent advances in using convolutional neural networks (CNNs) for image processing, it should be possible to use image diagnostics directly in control routines (NN-based or otherwise). This is especially appealing for non-intercepting diagnostics that could run continuously during beam operation. Here, we show results of a first step toward implementing such a controller: our trained CNN can predict multiple simulated downstream beam parameters at the Fermilab Accelerator Science and Technology (FAST) facility's low energy beamline using simulated virtual cathode laser images, gun phases, and solenoid strengths.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA51
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WEPOA15	Installation Progress at the PIP-II Injector Test at Fermilab	722
	C.M. Baffes, M.L. Alvarez, R. Andrews, A.Z. Chen, J. Czajkowski, P. Derwent, J.P. Edelen, B.M. Hanna, B.D. Hartsell, K.R. Kendziora, D.V. Mitchell, L.R. Prost, V.E. Scarpine, A.V. Shemyakin, J. Steimel, T.J. Zuchnik Fermilab, Batavia, Illinois, USA A.L. Edelen CSU, Fort Collins, Colorado, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy A CW-compatible, pulsed H⁻ superconducting linac 'PIP-II' is being planned to upgrade Fermilab's injection complex. To validate the concept of the front-end of such a machine, a test accelerator (The PIP-II Injector Test, formerly known as "PXIE") is under construction. The warm part of this accelerator comprises a 10 mA DC 30 keV H⁻ ion source, a 2m-long LEBT, a 2.1 MeV CW RFQ, and a 10-m long MEBT that is capable of creating a large variety of bunch structures. The paper will report on the installation of the RFQ and the first sections of the MEBT and related mechanical design considerations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA15
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WEPOB25	Analytical Modeling of Electron Back-Bombardment Induced Current Increase in Un-Gated Thermionic Cathode Rf Guns	953
	J.P. Edelen Fermilab, Batavia, Illinois, USA J.R. Harris Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA J.W. Lewellen LANL, Los Alamos, New Mexico, USA Y. Sun ANL, Argonne, Illinois, USA
	In this paper we derive analytical expressions for the output current of an un-gated thermionic cathode RF gun in the presence of back-bombardment heating. We provide a brief overview of back-bombardment theory and discuss comparisons between the analytical back-bombardment predictions and simulation models. We then derive an expression for the output current as a function of the RF repetition rate and discuss relationships between back-bombardment, field-enhancement, and output current. We discuss in detail the relevant approximations and then provide predictions about how the output current should vary as a function of repetition rate for some given system configurations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB25
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WEPOB26	Observation of Repetition-Rate Dependent Emission From an Un-Gated Thermionic Cathode Rf Gun	956
	J.P. Edelen Fermilab, Batavia, Illinois, USA J.R. Harris Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA J.W. Lewellen LANL, Los Alamos, New Mexico, USA Y. Sun ANL, Argonne, Illinois, USA
	Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an un-gated thermionic cathode RF gun to high average current.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB26
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Paper

Title

Page

Resonant Frequency Control for the PIP-II Injector Test RFQ: Control Framework and Initial Results

109

A.L. Edelen, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
D.L. Bowring, B.E. Chase, J.P. Edelen, D.J. Nicklaus, J. Steimel
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359.
For the PIP-II Injector Test (PI-Test) at Fermilab, a four-vane radio frequency quadrupole (RFQ) is designed to accelerate a 30-keV, 1-mA to 10-mA H' beam to 2.1 MeV under both pulsed and continuous wave (CW) RF operation. The available headroom of the RF amplifiers limit the maximum allowable detuning to 3 kHz, and the detuning is controlled entirely via thermal regulation. Fine control over the detuning, minimal manual intervention, and fast trip recovery is desired. In addition, having active control over both the walls and vanes provides a wider tuning range. For this, we intend to use model predictive control (MPC). To facilitate these objectives, we developed a dedicated control framework that handles higher-level system decisions as well as executes control calculations. It is written in Python in a modular fashion for easy adjustments, readability, and portability. Here we describe the framework and present the first control results for the PI-Test RFQ under pulsed and CW operation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB17

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TUPOA18

Low Level RF Control for the PIP-II Injector Test RFQ

323

J.P. Edelen, B.E. Chase, E. Cullerton, J. Einstein, P. Varghese
Fermilab, Batavia, Illinois, USA

The PIP-II injector test radio frequency quadrupole (RFQ) arrived at Fermilab in the fall of 2015. The RFQ is a 162.5MHz H⁻ accelerator with a nominal drive power of 100kW, which produces a bunched H⁻ beam at 2.1MeV. In this paper we discuss commissioning, operational performance, and improvements to the low level RF (LLRF) control system for the RFQ. We begin by describing the general system configuration and initial simulation results. We will then highlight temperature related issues in the high power RF system, which necessitate active control over the phase balance of the two amplifiers. Finally we demonstrate performance of the RF feedback and feed-forward compensation needed to meet specification during a 20-microsecond beam pulse.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA18

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TUPOA51

First Steps Toward Incorporating Image Based Diagnostics into Particle Accelerator Control Systems Using Convolutional Neural Networks

390

SUPO10

use link to see paper's listing under its alternate paper code

A.L. Edelen, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
J.P. Edelen
Fermilab, Batavia, Illinois, USA

At present, a variety of image-based diagnostics are used in particle accelerator systems. Often times, these are viewed by a human operator who then makes appropriate adjustments to the machine. Given recent advances in using convolutional neural networks (CNNs) for image processing, it should be possible to use image diagnostics directly in control routines (NN-based or otherwise). This is especially appealing for non-intercepting diagnostics that could run continuously during beam operation. Here, we show results of a first step toward implementing such a controller: our trained CNN can predict multiple simulated downstream beam parameters at the Fermilab Accelerator Science and Technology (FAST) facility's low energy beamline using simulated virtual cathode laser images, gun phases, and solenoid strengths.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA51

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WEPOA15

Installation Progress at the PIP-II Injector Test at Fermilab

722

C.M. Baffes, M.L. Alvarez, R. Andrews, A.Z. Chen, J. Czajkowski, P. Derwent, J.P. Edelen, B.M. Hanna, B.D. Hartsell, K.R. Kendziora, D.V. Mitchell, L.R. Prost, V.E. Scarpine, A.V. Shemyakin, J. Steimel, T.J. Zuchnik
Fermilab, Batavia, Illinois, USA
A.L. Edelen
CSU, Fort Collins, Colorado, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy
A CW-compatible, pulsed H⁻ superconducting linac 'PIP-II' is being planned to upgrade Fermilab's injection complex. To validate the concept of the front-end of such a machine, a test accelerator (The PIP-II Injector Test, formerly known as "PXIE") is under construction. The warm part of this accelerator comprises a 10 mA DC 30 keV H⁻ ion source, a 2m-long LEBT, a 2.1 MeV CW RFQ, and a 10-m long MEBT that is capable of creating a large variety of bunch structures. The paper will report on the installation of the RFQ and the first sections of the MEBT and related mechanical design considerations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA15

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WEPOB25

Analytical Modeling of Electron Back-Bombardment Induced Current Increase in Un-Gated Thermionic Cathode Rf Guns

953

J.P. Edelen
Fermilab, Batavia, Illinois, USA
J.R. Harris
Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA
Y. Sun
ANL, Argonne, Illinois, USA

In this paper we derive analytical expressions for the output current of an un-gated thermionic cathode RF gun in the presence of back-bombardment heating. We provide a brief overview of back-bombardment theory and discuss comparisons between the analytical back-bombardment predictions and simulation models. We then derive an expression for the output current as a function of the RF repetition rate and discuss relationships between back-bombardment, field-enhancement, and output current. We discuss in detail the relevant approximations and then provide predictions about how the output current should vary as a function of repetition rate for some given system configurations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB25

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WEPOB26

Observation of Repetition-Rate Dependent Emission From an Un-Gated Thermionic Cathode Rf Gun

956

J.P. Edelen
Fermilab, Batavia, Illinois, USA
J.R. Harris
Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA
Y. Sun
ANL, Argonne, Illinois, USA

Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an un-gated thermionic cathode RF gun to high average current.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB26

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