NAPAC2019 - List of Authors (Seok, J.)

Paper	Title	Page
WEPLM67	Optimization of a Single-Cell Accelerating Structure for Rf Breakdown Test With Short Rf Pulses	747
	M.M. Peng, J. Shi TUB, Beijing, People’s Republic of China M.E. Conde, G. Ha, C.-J. Jing, W. Liu, J.G. Power, J. Seok, J.H. Shao, E.E. Wisniewski ANL, Lemont, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA
	RF breakdown is one of the major limitations to achieve high gradient acceleration for future structure-based normal conducting linear colliders. Previous statistic research shows that the breakdown rate is proportional to E_a³⁰ * t_p⁵, which indicates that the accelerating gradient E_a could be improved by using shorter RF pulses (t_p). An X-band 11.7~GHz metallic single-cell structure has been designed for RF breakdown study up to 273~MV/m using short pulses (~3ns) generated by a 400~MW power extractor at Argonne Wakefield Accelerator (AWA) facility. The structure has also been scaled to 11.424~GHz for the long pulse (100-1500~ns) breakdown study driven by a klystron and a pulse compressor at Tsinghua X-band High Power Test-stand (TPoT-X), with the gradient up to 246~MV/m with 200~MW input power.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM67
About •	paper received ※ 05 September 2019 paper accepted ※ 26 November 2019 issue date ※ 08 October 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPLM68	Design of a Dielectric-Loaded Accelerator for Short Pulse High Gradient Research	751
	M.M. Peng, J. Shi TUB, Beijing, People’s Republic of China M.E. Conde, G. Ha, C.-J. Jing, W. Liu, J.G. Power, J. Seok, J.H. Shao, E.E. Wisniewski ANL, Lemont, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA
	The short-pulse two-beam acceleration approach is a promising candidate to meet the cost and luminosity requirements for future linear colliders. Dielectric-loaded structure has been intensely investigated for this approach because of its low fabrication cost, low RF loss, and potential to withstand GV/m gradient. An X-band 11.7~GHz dielectric-loaded accelerator (DLA) has been designed for high power test with short RF pulses (3~ns) generated from a power extractor driven by high charge bunches at Argonne Wakefield Accelerator (AWA) facility. The gradient is expected to be over 100~MV/m with the maximum input power of 400~MW.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM68
About •	paper received ※ 05 September 2019 paper accepted ※ 27 November 2019 issue date ※ 08 October 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOZBB2	Experiments with Metamaterial-Based Metallic Accelerating Structures	78
MOPLH20	use link to see paper's listing under its alternate paper code
	X. Lu SLAC, Menlo Park, California, USA M.E. Conde, D.S. Doran, G. Ha, J.G. Power, J.H. Shao, E.E. Wisniewski ANL, Lemont, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA X. Lu, I. Mastovsky, J.F. Picard, M.A. Shapiro, R.J. Temkin MIT/PSFC, Cambridge, Massachusetts, USA M.M. Peng AAI/ANL, Lemont, Illinois, USA J. Seok UNIST, Ulsan, Republic of Korea
	Funding: U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award No. DE-SC0015566 at MIT and No. DE-AC02-06CH11357 at ANL We present experimental studies of metamaterial (MTM) structures for wakefield acceleration. The MTM structure is an all-metal periodic structure with its period much smaller than the wavelength at X-band. The fundamental TM mode has a negative group velocity, so an electron beam traveling through the structure radiates by reversed Cherenkov radiation. Two experiments have been completed at the Argonne Wakefield Accelerator (AWA), namely the Stage-I and Stage-II experiments. Differences between the two experiments include: (1) Structure length (Stage-I 8 cm, Stage-II 20 cm); (2) Bunch number used to excite the structure (Stage-I up to 2 bunches, Stage-II up to 8 bunches). In the Stage-I experiment, two bunches with a total charge of 85 nC generated 80 MW of RF power in a 2 ns long pulse. In the Stage-II experiment, the highest peak power reached 380 MW in a 10 ns long pulse from a train of 8 bunches with a total charge of 224 nC. Acceleration of a witness bunch has not been demonstrated yet, but the extracted power can be transferred to a separate accelerator for two-beam acceleration or directly applied to a trailing witness bunch in the same structure for collinear acceleration.
	Slides MOZBB2 [8.172 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBB2
About •	paper received ※ 27 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPLM16	Double-Horn Suppression in EEX Based Bunch Compression	407
	J. Seok, M. Chung UNIST, Ulsan, Republic of Korea M.E. Conde, G. Ha, J.G. Power ANL, Lemont, Illinois, USA
	Nonlinearities on the longitudinal phase space in-duce a double-horn current profile when the bunch is compressed strongly. Since this double-horn can de-grade the performance of FELs due to the CSR it makes, the suppression of the double-horn is one of important beam dynamics issues. Emittance exchange (EEX) can be interesting option for this issue due to its longitudinal controllability. Since EEX exchanges the longitudinal phase space and transverse phase space, higher order magnets such as octupole can control the nonlinearity. In this paper, we present simulation re-sults on the suppression of the double-horn current profile using EEX based bunch compression. We use a double EEX beamline installed at the Argonne Wake-field Accelerator facility for the simulation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM16
About •	paper received ※ 03 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPLO19	Probing Multiperiod Plasma Response Regimes using Single Shot Wakefield Measurements	878
	R.J. Roussel, G. Andonian, W.J. Lynn, J.B. Rosenzweig UCLA, Los Angeles, California, USA M.E. Conde, D.S. Doran, G. Ha, J.G. Power, C. Whiteford, E.E. Wisniewski ANL, Lemont, Illinois, USA J. Seok UNIST, Ulsan, Republic of Korea
	Funding: DE-SC0017648 Systematic differences between the linear and nonlinear regimes of plasma wakefield acceleration from electron beams are manifested in the plasma response. Typically, the ratio of peak beam density to nominal plasma density determines operation in the linear or nonlinear regime. Previous reports have shown that a the cross-over into the nonlinear regime is associated with an increase in the wakefield amplitude, as well as sawtooth-like shape. In this paper, we present preliminary measurements of quasi-nonlinear wakefields driven by a linearly ramped beam, with a maximum charge close to the unperturbed plasma density. We also demonstrate nonlinear wakefield behavior in a probe bunch using a single shot, multi-period wakefield measurement and its dependency on plasma density.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO19
About •	paper received ※ 31 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

FRXBA3	Applications and Opportunities for the Emittance Exchange Beamline	981
	G. Ha, M.E. Conde, J.G. Power ANL, Lemont, Illinois, USA M. Chung, J. Seok UNIST, Ulsan, Republic of Korea
	Funding: This work is supported by the U.S. Department of Energy, Offices of HEP and BES, under Contract No. DE-AC02-06CH11357. Emittance exchange (EEX) provides a powerful method of controlling the longitudinal phase space using the relatively simpler methods of transverse control. An EEX beamline was installed at the Argonne Wakefield Accelerator (AWA) facility in 2015. Several experiments important to the wakefield acceleration, such as a high transformer ratio from shaped bunches, have already been demonstrated. We are currently developing several applications of the EEX beamline including temporal profile shaping, THz radiation generation, time-energy correlation control, diagnostic uses of EEX etc. We will present the on-going EEX program for longitudinal phase space control taking place at the AWA facility, and discuss recently discovered new opportunities.
	Slides FRXBA3 [6.814 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-FRXBA3
About •	paper received ※ 02 September 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Optimization of a Single-Cell Accelerating Structure for Rf Breakdown Test With Short Rf Pulses

747

M.M. Peng, J. Shi
TUB, Beijing, People’s Republic of China
M.E. Conde, G. Ha, C.-J. Jing, W. Liu, J.G. Power, J. Seok, J.H. Shao, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA

RF breakdown is one of the major limitations to achieve high gradient acceleration for future structure-based normal conducting linear colliders. Previous statistic research shows that the breakdown rate is proportional to E_a³⁰ * t_p⁵, which indicates that the accelerating gradient E_a could be improved by using shorter RF pulses (t_p). An X-band 11.7~GHz metallic single-cell structure has been designed for RF breakdown study up to 273~MV/m using short pulses (~3ns) generated by a 400~MW power extractor at Argonne Wakefield Accelerator (AWA) facility. The structure has also been scaled to 11.424~GHz for the long pulse (100-1500~ns) breakdown study driven by a klystron and a pulse compressor at Tsinghua X-band High Power Test-stand (TPoT-X), with the gradient up to 246~MV/m with 200~MW input power.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM67

About •

paper received ※ 05 September 2019 paper accepted ※ 26 November 2019 issue date ※ 08 October 2019

Export •

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

WEPLM68

Design of a Dielectric-Loaded Accelerator for Short Pulse High Gradient Research

751

M.M. Peng, J. Shi
TUB, Beijing, People’s Republic of China
M.E. Conde, G. Ha, C.-J. Jing, W. Liu, J.G. Power, J. Seok, J.H. Shao, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA

The short-pulse two-beam acceleration approach is a promising candidate to meet the cost and luminosity requirements for future linear colliders. Dielectric-loaded structure has been intensely investigated for this approach because of its low fabrication cost, low RF loss, and potential to withstand GV/m gradient. An X-band 11.7~GHz dielectric-loaded accelerator (DLA) has been designed for high power test with short RF pulses (3~ns) generated from a power extractor driven by high charge bunches at Argonne Wakefield Accelerator (AWA) facility. The gradient is expected to be over 100~MV/m with the maximum input power of 400~MW.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM68

About •

paper received ※ 05 September 2019 paper accepted ※ 27 November 2019 issue date ※ 08 October 2019

Export •

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

MOZBB2

Experiments with Metamaterial-Based Metallic Accelerating Structures

78

MOPLH20

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

X. Lu
SLAC, Menlo Park, California, USA
M.E. Conde, D.S. Doran, G. Ha, J.G. Power, J.H. Shao, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
X. Lu, I. Mastovsky, J.F. Picard, M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA
M.M. Peng
AAI/ANL, Lemont, Illinois, USA
J. Seok
UNIST, Ulsan, Republic of Korea

Funding: U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award No. DE-SC0015566 at MIT and No. DE-AC02-06CH11357 at ANL
We present experimental studies of metamaterial (MTM) structures for wakefield acceleration. The MTM structure is an all-metal periodic structure with its period much smaller than the wavelength at X-band. The fundamental TM mode has a negative group velocity, so an electron beam traveling through the structure radiates by reversed Cherenkov radiation. Two experiments have been completed at the Argonne Wakefield Accelerator (AWA), namely the Stage-I and Stage-II experiments. Differences between the two experiments include: (1) Structure length (Stage-I 8 cm, Stage-II 20 cm); (2) Bunch number used to excite the structure (Stage-I up to 2 bunches, Stage-II up to 8 bunches). In the Stage-I experiment, two bunches with a total charge of 85 nC generated 80 MW of RF power in a 2 ns long pulse. In the Stage-II experiment, the highest peak power reached 380 MW in a 10 ns long pulse from a train of 8 bunches with a total charge of 224 nC. Acceleration of a witness bunch has not been demonstrated yet, but the extracted power can be transferred to a separate accelerator for two-beam acceleration or directly applied to a trailing witness bunch in the same structure for collinear acceleration.

Slides MOZBB2 [8.172 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBB2

About •

paper received ※ 27 August 2019 paper accepted ※ 04 September 2019 issue date ※ 08 October 2019

Export •

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

TUPLM16

Double-Horn Suppression in EEX Based Bunch Compression

407

J. Seok, M. Chung
UNIST, Ulsan, Republic of Korea
M.E. Conde, G. Ha, J.G. Power
ANL, Lemont, Illinois, USA

Nonlinearities on the longitudinal phase space in-duce a double-horn current profile when the bunch is compressed strongly. Since this double-horn can de-grade the performance of FELs due to the CSR it makes, the suppression of the double-horn is one of important beam dynamics issues. Emittance exchange (EEX) can be interesting option for this issue due to its longitudinal controllability. Since EEX exchanges the longitudinal phase space and transverse phase space, higher order magnets such as octupole can control the nonlinearity. In this paper, we present simulation re-sults on the suppression of the double-horn current profile using EEX based bunch compression. We use a double EEX beamline installed at the Argonne Wake-field Accelerator facility for the simulation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLM16

About •

paper received ※ 03 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

Export •

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

WEPLO19

Probing Multiperiod Plasma Response Regimes using Single Shot Wakefield Measurements

878

R.J. Roussel, G. Andonian, W.J. Lynn, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
M.E. Conde, D.S. Doran, G. Ha, J.G. Power, C. Whiteford, E.E. Wisniewski
ANL, Lemont, Illinois, USA
J. Seok
UNIST, Ulsan, Republic of Korea

Funding: DE-SC0017648
Systematic differences between the linear and nonlinear regimes of plasma wakefield acceleration from electron beams are manifested in the plasma response. Typically, the ratio of peak beam density to nominal plasma density determines operation in the linear or nonlinear regime. Previous reports have shown that a the cross-over into the nonlinear regime is associated with an increase in the wakefield amplitude, as well as sawtooth-like shape. In this paper, we present preliminary measurements of quasi-nonlinear wakefields driven by a linearly ramped beam, with a maximum charge close to the unperturbed plasma density. We also demonstrate nonlinear wakefield behavior in a probe bunch using a single shot, multi-period wakefield measurement and its dependency on plasma density.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLO19

About •

paper received ※ 31 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

Export •

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

FRXBA3

Applications and Opportunities for the Emittance Exchange Beamline

981

G. Ha, M.E. Conde, J.G. Power
ANL, Lemont, Illinois, USA
M. Chung, J. Seok
UNIST, Ulsan, Republic of Korea

Funding: This work is supported by the U.S. Department of Energy, Offices of HEP and BES, under Contract No. DE-AC02-06CH11357.
Emittance exchange (EEX) provides a powerful method of controlling the longitudinal phase space using the relatively simpler methods of transverse control. An EEX beamline was installed at the Argonne Wakefield Accelerator (AWA) facility in 2015. Several experiments important to the wakefield acceleration, such as a high transformer ratio from shaped bunches, have already been demonstrated. We are currently developing several applications of the EEX beamline including temporal profile shaping, THz radiation generation, time-energy correlation control, diagnostic uses of EEX etc. We will present the on-going EEX program for longitudinal phase space control taking place at the AWA facility, and discuss recently discovered new opportunities.

Slides FRXBA3 [6.814 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-FRXBA3

About •

paper received ※ 02 September 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019

Export •

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