IPAC2018 - List of Authors (Ruan, J.)

Paper	Title	Page
TUXGBF2	Higher-Order-Mode Effects in Tesla-Type Superconducting RF Cavities on Electron Beam Quality	612
	A.H. Lumpkin, N. Eddy, D.R. Edstrom, P.S. Prieto, J. Ruan, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA K. Bishofberger, B.E. Carlsten LANL, Los Alamos, New Mexico, USA O. Napoly CEA/DSM/IRFU, France
	Funding: Work at Fermilab supported by FRA, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Dept. of Energy. *Work at LANL supported by U.S. Dept. of Energy through the LANL/LDRD Program. We report the direct observations of the correlation of higher order modes (HOMs) generated by off-axis electron beam steering in TESLA-type SCRF cavities and sub-macropulse beam centroid shifts (with the concomitant effect on averaged beam size and emittance). The experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility using its unique configuration of a PC rf gun injecting beam into two separated 9-cell cavities in series with corrector magnets and beam position monitors (BPMs) located before, between, and after them. The ~100-kHz oscillations with up to 300-μm amplitudes at downstream locations were observed in a 3-MHz micropulse repetition rate beam with charges of 500 and 1000 pC/b, although the effects were much reduced at 100 pC/b. The studies were based on HOM detector circuitry targeting the first and second dipole passbands, rf BPM bunch-by-bunch data, and imaging cameras viewing multi-slit images for emittance assessments at 33 MeV. Initial calculations reproduced a key feature of the phenomena. In principle, these results may be scaled to cryomodule configurations of major accelerator facilities.
	Slides TUXGBF2 [3.631 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBF2
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THPAK061	Magnetized and Flat Beam Generation at the Fermilab's FAST Facility	3364
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA D.J. Crawford, D.R. Edstrom, D. Mihalcea, S. Nagaitsev, P. Piot, A.L. Romanov, J. Ruan, V.D. Shiltsev Fermilab, Batavia, Illinois, USA
	Funding: This work is supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. A.H. is supported by the DOE under contract No. DE-SC0011831 with Northern Illinois University. Canonical angular momentum (CAM) dominated beams can be formed in photoinjectors by applying an axial magnetic field on the photocathode surface. Such a beam possess asymmetric eigenemittances and is characterized by the measure of its magnetization. CAM removal using a set skew-quadrupole magnets maps the beam eigenemittances to the conventional emittance along each transverse degree of freedom thereby yielding flat beam with asymmetric transverse emittance. In this paper we report on the experimental generation of CAM dominated beam and their subsequent transformation into flat beams at the Fermilab Accelerator Science and Technology (FAST) facility. Our results are compared with numerical simulations and possible applications of the produced beams are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK061
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THPAK062	Bunch Compression of Flat Beams	3368
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA D.J. Crawford, D.R. Edstrom, D. Mihalcea, S. Nagaitsev, P. Piot, A.L. Romanov, J. Ruan, V.D. Shiltsev Fermilab, Batavia, Illinois, USA
	Funding: This work is supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. A.H. is supported by the DOE under contract No. DE-SC0011831 with Northern Illinois University. Flat beams can be produced via a linear manipulation of canonical angular momentum (CAM) dominated beams using a set of skew-quadrupole magnets. Recently such beams were produced at Fermilab Accelerator Science and Technology (FAST) facility. In this paper, we report the results of flat beam compression study in a magnetic chicane at an energy of E~32 MeV. Additionally, we investigate the effect of energy chirp in the round-to-flat beam transform. The experimental results are compared with numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK062
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THPMF024	Commissioning and Operation of FAST Electron Linac at Fermilab	4096
	A.L. Romanov, C.M. Baffes, D.R. Broemmelsiek, K. Carlson, D.J. Crawford, N. Eddy, D.R. Edstrom, E.R. Harms, J. Hurd, M.J. Kucera, J.R. Leibfritz, I.L. Rakhno, J. Reid, J. Ruan, J.K. Santucci, V.D. Shiltsev, G. Stancari, R.M. Thurman-Keup, A. Valishev, A. Warner Fermilab, Batavia, Illinois, USA
	We report results of the beam commissioning and first operation of the 1.3 GHz superconducting RF electron linear accelerator at Fermilab Accelerator Science and Technology (FAST) facility. Construction of the linac was completed and the machine was commissioned with beam in 2017. The maximum total beam energy of about 300 MeV was achieved with the record energy gain of 250 MeV in the ILC-type SRF cryomodule. The pho-toinjector was tuned to produce trains of 200 pC bunches with a frequency of 3 MHz at a repetition rate of 1 Hz. This report describes the aspects of machine commission-ing such as tuning of the SRF cryomodule and beam optics optimization. We also present highlights of an experimental program carried out parasitically during the two-month run, including studies of wake-fields, and advanced beam phase space manipulation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF024
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THPMF025	Emittance Measurements at FAST Facility	4100
	J. Ruan, D.R. Broemmelsiek, D.J. Crawford, A.L. Edelen, J.P. Edelen, D.R. Edstrom, A.H. Lumpkin, P. Piot, A.L. Romanov, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The FAST facility at Fermilab recently been commissioned has demonstrated the generation of electron beam within a wide range of parameter (energy, charge) suitable for accelerator-science and beam-physics experiments. This accelerator consists of a photo-electron gun, injector, ILC-type cryomodules, and multiple downstream beam-lines. It will mainly serve as injector for the upcoming Integrable Optical Test Accelerator (IOTA). At the same time we will also carry out a LINAC based intense gamma ray experiment based on the Inverse Compton scattering. It is essential to understand the beam emittance for both experiments. A number of techniques are used to characaterizing the beam emittance including slit based method and quad scan method. An on-line emittance measurement based on multi-slit method is developed so the emittance measured will be immediately available to support further beam optimization. In this report we will present the results from the emittance studies using this tool. We will also present the emittance measurement based on quads scan technique for the high energy beam line.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF025
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THPMF028	Coherent Stacking Scheme for Inverse-Compton Scattering at MHz Repetition Rates	4103
	P. Piot, D. Mihalcea Northern Illinois University, DeKalb, Illinois, USA T.J. Campese, A.Y. Murokh RadiaBeam Systems, Santa Monica, California, USA D. Mihalcea, P. Piot, J. Ruan Fermilab, Batavia, Illinois, USA
	Funding: Work sponsored by the DNDO award 2015-DN-077-ARI094 to Northern Illinois University and US DOE contract DE-AC02-07CH11359 to Fermilab. An experiment to produce 1-MeV gamma rays via Compton back-scattering of infrared photons on 250-MeV electron bunches is currently in preparation at the Fermilab Accelerator Science & Technology (FAST) facility. To increase the gamma-ray flux the energy of the infrared laser pulses are planned to be amplified within the interaction region using a resonant cavity. This passive amplifier composed of a Fabry-Perot cavity will allow the laser pulse bunches to coherently and constructively stack. Our estimates, based on theoretical models, show that the laser pulse energy can be increased from approximately 1-2 mJ at the exit of the last active amplifier to 5 -10 mJ at the interaction point when the laser repetition rate is set at the nominal value of 3 MHz. This paper details the cavity design option(s) and associated wave-optic simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF028
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THPML063	Micro-Bunched Beam Production at FAST for Narrow Band THz Generation Using a Slit-Mask	4784
	J. Hyun Sokendai, Ibaraki, Japan D.J. Crawford, D.R. Edstrom, J. Ruan, J.K. Santucci, T. Sen, J.C.T. Thangaraj, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA
	We discuss simulations and experiments on creating micro-bunch beams for generating narrow band THz radiation at the Fermilab Accelerator Science and Technology (FAST) facility. The low-energy electron beamline at FAST consists of a photoinjector-based RF gun, two L-band superconducting accelerating cavities, a chicane, and a beam dump. The electron bunches are lengthened with cavity phases set off-crest for better longitudinal separation and then micro-bunched with a slit-mask installed in the chicane. We carried out the experiments with 30 MeV electron beams and detected signals of the micro-bunching using a skew quadrupole magnet in the chicane. In this paper, the details of micro-bunch beam production, the detection of micro-bunching and comparison with simulations are described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML063
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Paper

Title

Page

Higher-Order-Mode Effects in Tesla-Type Superconducting RF Cavities on Electron Beam Quality

612

A.H. Lumpkin, N. Eddy, D.R. Edstrom, P.S. Prieto, J. Ruan, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA
K. Bishofberger, B.E. Carlsten
LANL, Los Alamos, New Mexico, USA
O. Napoly
CEA/DSM/IRFU, France

Funding: *Work at Fermilab supported by FRA, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Dept. of Energy. **Work at LANL supported by U.S. Dept. of Energy through the LANL/LDRD Program.
We report the direct observations of the correlation of higher order modes (HOMs) generated by off-axis electron beam steering in TESLA-type SCRF cavities and sub-macropulse beam centroid shifts (with the concomitant effect on averaged beam size and emittance). The experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility using its unique configuration of a PC rf gun injecting beam into two separated 9-cell cavities in series with corrector magnets and beam position monitors (BPMs) located before, between, and after them. The ~100-kHz oscillations with up to 300-μm amplitudes at downstream locations were observed in a 3-MHz micropulse repetition rate beam with charges of 500 and 1000 pC/b, although the effects were much reduced at 100 pC/b. The studies were based on HOM detector circuitry targeting the first and second dipole passbands, rf BPM bunch-by-bunch data, and imaging cameras viewing multi-slit images for emittance assessments at 33 MeV. Initial calculations reproduced a key feature of the phenomena. In principle, these results may be scaled to cryomodule configurations of major accelerator facilities.

Slides TUXGBF2 [3.631 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBF2

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THPAK061

Magnetized and Flat Beam Generation at the Fermilab's FAST Facility

3364

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
D.J. Crawford, D.R. Edstrom, D. Mihalcea, S. Nagaitsev, P. Piot, A.L. Romanov, J. Ruan, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

Funding: This work is supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. A.H. is supported by the DOE under contract No. DE-SC0011831 with Northern Illinois University.
Canonical angular momentum (CAM) dominated beams can be formed in photoinjectors by applying an axial magnetic field on the photocathode surface. Such a beam possess asymmetric eigenemittances and is characterized by the measure of its magnetization. CAM removal using a set skew-quadrupole magnets maps the beam eigenemittances to the conventional emittance along each transverse degree of freedom thereby yielding flat beam with asymmetric transverse emittance. In this paper we report on the experimental generation of CAM dominated beam and their subsequent transformation into flat beams at the Fermilab Accelerator Science and Technology (FAST) facility. Our results are compared with numerical simulations and possible applications of the produced beams are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK061

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THPAK062

Bunch Compression of Flat Beams

3368

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
D.J. Crawford, D.R. Edstrom, D. Mihalcea, S. Nagaitsev, P. Piot, A.L. Romanov, J. Ruan, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

Funding: This work is supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. A.H. is supported by the DOE under contract No. DE-SC0011831 with Northern Illinois University.
Flat beams can be produced via a linear manipulation of canonical angular momentum (CAM) dominated beams using a set of skew-quadrupole magnets. Recently such beams were produced at Fermilab Accelerator Science and Technology (FAST) facility. In this paper, we report the results of flat beam compression study in a magnetic chicane at an energy of E~32 MeV. Additionally, we investigate the effect of energy chirp in the round-to-flat beam transform. The experimental results are compared with numerical simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK062

Export •

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

THPMF024

Commissioning and Operation of FAST Electron Linac at Fermilab

4096

A.L. Romanov, C.M. Baffes, D.R. Broemmelsiek, K. Carlson, D.J. Crawford, N. Eddy, D.R. Edstrom, E.R. Harms, J. Hurd, M.J. Kucera, J.R. Leibfritz, I.L. Rakhno, J. Reid, J. Ruan, J.K. Santucci, V.D. Shiltsev, G. Stancari, R.M. Thurman-Keup, A. Valishev, A. Warner
Fermilab, Batavia, Illinois, USA

We report results of the beam commissioning and first operation of the 1.3 GHz superconducting RF electron linear accelerator at Fermilab Accelerator Science and Technology (FAST) facility. Construction of the linac was completed and the machine was commissioned with beam in 2017. The maximum total beam energy of about 300 MeV was achieved with the record energy gain of 250 MeV in the ILC-type SRF cryomodule. The pho-toinjector was tuned to produce trains of 200 pC bunches with a frequency of 3 MHz at a repetition rate of 1 Hz. This report describes the aspects of machine commission-ing such as tuning of the SRF cryomodule and beam optics optimization. We also present highlights of an experimental program carried out parasitically during the two-month run, including studies of wake-fields, and advanced beam phase space manipulation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF024

Export •

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

THPMF025

Emittance Measurements at FAST Facility

4100

J. Ruan, D.R. Broemmelsiek, D.J. Crawford, A.L. Edelen, J.P. Edelen, D.R. Edstrom, A.H. Lumpkin, P. Piot, A.L. Romanov, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: *Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The FAST facility at Fermilab recently been commissioned has demonstrated the generation of electron beam within a wide range of parameter (energy, charge) suitable for accelerator-science and beam-physics experiments. This accelerator consists of a photo-electron gun, injector, ILC-type cryomodules, and multiple downstream beam-lines. It will mainly serve as injector for the upcoming Integrable Optical Test Accelerator (IOTA). At the same time we will also carry out a LINAC based intense gamma ray experiment based on the Inverse Compton scattering. It is essential to understand the beam emittance for both experiments. A number of techniques are used to characaterizing the beam emittance including slit based method and quad scan method. An on-line emittance measurement based on multi-slit method is developed so the emittance measured will be immediately available to support further beam optimization. In this report we will present the results from the emittance studies using this tool. We will also present the emittance measurement based on quads scan technique for the high energy beam line.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF025

Export •

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

THPMF028

Coherent Stacking Scheme for Inverse-Compton Scattering at MHz Repetition Rates

4103

P. Piot, D. Mihalcea
Northern Illinois University, DeKalb, Illinois, USA
T.J. Campese, A.Y. Murokh
RadiaBeam Systems, Santa Monica, California, USA
D. Mihalcea, P. Piot, J. Ruan
Fermilab, Batavia, Illinois, USA

Funding: Work sponsored by the DNDO award 2015-DN-077-ARI094 to Northern Illinois University and US DOE contract DE-AC02-07CH11359 to Fermilab.
An experiment to produce 1-MeV gamma rays via Compton back-scattering of infrared photons on 250-MeV electron bunches is currently in preparation at the Fermilab Accelerator Science & Technology (FAST) facility. To increase the gamma-ray flux the energy of the infrared laser pulses are planned to be amplified within the interaction region using a resonant cavity. This passive amplifier composed of a Fabry-Perot cavity will allow the laser pulse bunches to coherently and constructively stack. Our estimates, based on theoretical models, show that the laser pulse energy can be increased from approximately 1-2 mJ at the exit of the last active amplifier to 5 -10 mJ at the interaction point when the laser repetition rate is set at the nominal value of 3 MHz. This paper details the cavity design option(s) and associated wave-optic simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF028

Export •

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

THPML063

Micro-Bunched Beam Production at FAST for Narrow Band THz Generation Using a Slit-Mask

4784

J. Hyun
Sokendai, Ibaraki, Japan
D.J. Crawford, D.R. Edstrom, J. Ruan, J.K. Santucci, T. Sen, J.C.T. Thangaraj, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA

We discuss simulations and experiments on creating micro-bunch beams for generating narrow band THz radiation at the Fermilab Accelerator Science and Technology (FAST) facility. The low-energy electron beamline at FAST consists of a photoinjector-based RF gun, two L-band superconducting accelerating cavities, a chicane, and a beam dump. The electron bunches are lengthened with cavity phases set off-crest for better longitudinal separation and then micro-bunched with a slit-mask installed in the chicane. We carried out the experiments with 30 MeV electron beams and detected signals of the micro-bunching using a skew quadrupole magnet in the chicane. In this paper, the details of micro-bunch beam production, the detection of micro-bunching and comparison with simulations are described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML063

Export •

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