IPAC2018 - List of Authors (Antipov, S.P.)

Paper	Title	Page
MOPML029	A Portable X-ray Source Based on Dielectric Accelerators	464
	C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA S.P. Antipov, A. Kanareykin, R.A. Kostin Euclid Beamlabs LLC, Bolingbrook, USA
	Funding: The work has been supported by the U.S. Department of Homeland Security (DHS), Domestic Nuclear Detection Office (DNDO), under a competitively awarded contract No. HSHQDC-17-C-00007. The portable low energy accelerator based X-ray sources have attractive applications in the non-destructive examination as a replacement of radiological gamma isotope sources. We are developing an inexpensive ultra-compact dielectric accelerator technology for low energy electron beams. The portability in the realm of this proposal is unprecedented ~ 1 ft3 volume with ~ 50 lbs of weight. The use of ceramics makes the transverse size of the accelerating waveguide comparable to that of a pencil. Because of this size reduction, additional weight reduction of shielding becomes possible. The article will report on the progress of this project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML029
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TUPML006	Updates of the Argonne Cathode Test-stand	1542
	J.H. Shao, M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.F. Power, C. Whiteford, E.E. Wisniewski, L.M. Zheng ANL, Argonne, Illinois, USA S.P. Antipov, G. Chen, E. Gomez, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA S.V. Baryshev Michigan State University, East Lansing, Michigan, USA
	The Argonne Cathode Test-stand (ACT) is a unique testbed to develop cathodes and to conduct fundamental surface study under ultra-high rf field (up to 700 MV/m with pin-shaped cathodes). The test-stand consists of an L-band 1.3 GHz single-cell photocathode rf gun and a field emission (FE) imaging system to locate emitters with a resolution of ∼20 𝜇m. In the recent upgrade, UV laser has been introduced to improve the imaging system and to significantly expand the ACT towards photoemission and laser-assisted field emission research. In addition, a load-lock system has been added to the beam line to expedite the cathode switching period. The paper will present details of the upgrade as well as experiments planned in the near future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML006
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TUPML061	Study of Mean Transverse Energy of (N)UNCD with Tunable Laser Source	1677
SUSPF050	use link to see paper's listing under its alternate paper code
	G. Chen IIT, Chicago, Illinois, USA G. Adhikari, W.A. Schroeder UIC, Chicago, Illinois, USA S.P. Antipov, C.-J. Jing, K. Kovi Euclid TechLabs, LLC, Solon, Ohio, USA S.V. Baryshev ANL, Argonne, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: NSF grant No. NSF-1739150, DOE SBIR program grant No. DE-SC0013145, NSF grant No. PHYS-1535279, DOE Contract No. DE-AC02-06CH11357. There is a strong motivation to develop and understand novel materials with the potential to be utilized as photocathodes, as these could have desirable photoemission properties for research and industrial applications. Nitrogen-incorporated ultrananocrystalline diamond ((N)UNCD) photocathodes have potential to become a material of choice for photocathode applications. (N)UNCD has high quantum efficiency when processed in hydrogen plasma, low surface roughness, and high electron conductivity through the bulk*. The mean transverse energy (MTE) was calculated for (N)UNCD thin films using the double-solenoid scan method. (N)UNCD thin film with thickness of 160nm was deposited on highly-doped silicon substrate. Studies of the MTE of a (N)UNCD sample were done using a tunable laser source with photon energies of 3.56 eV to 5.26 eV. These results are presented. K.J. Pérez Quintero et al., Appl. Phys. Lett. 105, 123103 (2014). ** S. Bhattacharyya et al., Appl. Phys. Lett. 79, 1441 (2001)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML061
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WEPAF058	Detection of X-Rays and Charged Particles via Detuning of the Microwave Resonator	1958
	S.P. Antipov Euclid TechLabs, LLC, Solon, Ohio, USA S.V. Kuzikov Euclid Beamlabs LLC, Bolingbrook, USA S. Stoupin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	Funding: DOE SBIR Critically coupled microwave resonator is a finely balanced system, reflection at the resonance is virtually zero. Small changes in dielectric properties of resonator parts destroy this balance, small reflection can be detected from the resonator. This measurement is used in electron paramagnetic resonance studies. In this paper we discuss two accelerator - related applications of this technology. First is related to beam halo measurement taking advantage of high sensitivity of the microwave measurement. High energy particles crossing the diamond inside of a tuned resonator induce a weak conductivity in the sensing material. This small change results in resonator decoupling providing a signal proportional to a number of particles crossing the diamond plate. Second application considered is the x-ray flux monitoring. In this case it is x-ray induced photoconductivity which alters resonator coupling and produces a signal. Interestingly, sensing dielectric material embedded in a resonator can be a diamond or kapton window, refractive lens or part of a silicon monochromator. Thus an inevitable x-ray absorption on optical elements of the beamline is used to monitor x-ray flux online.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF058
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WEPAF060	Non-Invasive Bunch Length Diagnostics for High Intensity Beams	1964
	S.V. Kuzikov, S.P. Antipov Euclid TechLabs, LLC, Solon, Ohio, USA S.V. Kuzikov, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	Modern particle accelerators utilize photoinjectors and compression schemes to produce short high peak current electron bunches for various applications like x-ray free electron lasers, high gradient beam driven acceleration and others. Bunch length detection is a desired diagnostics for such machines. In this paper we describe a non-invasive, real-time detector which can be retrofitted into an existing beamline and measure the bunch length in real time using interferometric methods. Diffraction radiation is the mechanism to be used to produce a measurable signal without intercepting the beam. This became possible as sensitivity of pyrodetectors improved over the years, while peak beam power grew. For high peak current beams there is a possibility of a single shot measurement. This can be done with a pair of closely placed vacuum breaks that create a spatial correlation of the generated signals which can be measured by a pyro-detector array or a THz camera. The bunch length is determined from the correlation data using an iterative beam profile recovery algorithm.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF060
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WEPMF068	Inexpensive Brazeless Accelerator Prototype	2528
	S.P. Antipov, R.A. Kostin, S.V. Kuzikov Euclid TechLabs, LLC, Solon, Ohio, USA A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	Funding: DOE SBIR A simple, inexpensive way to manufacture a standard radio frequency (RF) driven particle accelerator is presented. The simplification comes from two innovations: utilization of LCLS gun type RF design to avoid an expensive brazing process and copper plating of stainless steel that further reduces manufacturing cost. This is realized by a special structure design where accelerating structure cells are made out of copper plated stainless steel with knife edges and structure irises - copper disks acts also as gaskets for vacuum and RF seal. Besides the reduced cost, brazeless assembly allows integration of effective cooling and magnet optics elements into accelerator cells. Here we report on manufacturing and testing of brazeless accelerator prototype.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF068
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WEPMF069	High Shunt Impedance Accelerating Structure with Distributed Microwave Coupling	2531
	S.P. Antipov, R.A. Kostin, S.V. Kuzikov Euclid TechLabs, LLC, Solon, Ohio, USA V.A. Dolgashev SLAC, Menlo Park, California, USA
	Funding: DOE SBIR Conventional traveling wave or pi-phase advance standing wave structures use coupling of the microwave power through the beam pipe. This feature constrains the cavity shunt impedance (efficiency) to relatively small values. As microwave power flows through the accelerating cells in such structures, the probability of breakdown in high gradient operation is greatly increased. In this paper we present results from an accelerating structure prototype with distributed microwave coupling, an approach invented at SLAC. These structures include one or more parallel waveguides which are loaded by accelerating cavities. In this configuration accelerating cavities are fed independently and completely isolated at the beam pipe. Thus there is no microwave power flow through the accelerating cavity, making this geometry favorable for high gradient operation and maximizing the shunt impedance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF069
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THPMF011	Femtosecond Laser Ablation for Manufacturing of X-ray Lenses and Phase Corrector Plates	4057
	S.P. Antipov Euclid TechLabs, LLC, Solon, Ohio, USA L. Assoufid, W.C. Grizolli, J. Qian, X. Shi ANL, Argonne, Illinois, USA
	Funding: DOE SBIR The next generation light sources such as diffraction limited storage rings and high repetition rate free electron lasers (FELs) will generate X-ray beams with significantly increased peak and average brilliance. These future facilities will require X-ray optical components capable of handling large instantaneous and average power densities while tailoring the properties of the X-ray beams for a variety of scientific experiments. In this paper we report on research and development of a single crystal diamond compound refractive lens. Diamond lenses presented here are fabricated by fs-laser cutting and subsequent polishing. Grating interferometry measurement data of these lenses had been performed at the Advanced Photon Source (Argonne). Besides the lenses, we fabricated and tested several phase correction plates, a refractive elements designed to correct for cumulative X-ray beam aberrations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF011
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THPMF012	Tapered Flying Radiofrequency Undulator	4059
	S.P. Antipov, S.V. Kuzikov, A. Liu Euclid TechLabs, LLC, Solon, Ohio, USA S.V. Kuzikov, A.V. Savilov, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	Funding: DOE SBIR DE-SC0017145 The x-ray free electron laser (x-FEL) efficiency, measured as a fraction of the electron beam power converted into light, is typically below 0.1% for most of the x-FEL facilities presently in operation. Undulator tapering techniques can be used to improve the conversion efficiency by 1-2 orders of magnitude. However at present there are no robust tapered undulator x-FEL schemes operating at 10% efficiency. In this paper we report on the development of tapered radiofrequency (RF) undulator. An RF undulator is a microwave waveguide in which strong RF field is excited that interacts with a charged particle beam forcing it to radiate coherent x-rays while undergoing a wiggling motion. RF undulators are attractive for use in x-FELs due to their large beam aperture and a short undulator period. Strongly tapered RF undulators (with tapering of a wavelength) due to non-resonant trapping regime allow keeping high overall XFEL efficiency being driven by laser plasma accelerated beams usually having high enough current but large energy spread (1-10%).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF012
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THPMF048	Bunch Length Measurements Using CTR at the AWA with Comparison to Simulation	4166
	N.R. Neveu IIT, Chicago, Illinois, USA S.P. Antipov Euclid TechLabs, LLC, Solon, Ohio, USA A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA J.G. Power, C. Whiteford, E.E. Wisniewski ANL, Argonne, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357. In this paper we present electron bunch length measurements at the Argonne Wakefield Accelerator (AWA) photoinjector facility. The AWA accelerator has a large dynamic charge density range, with electron beam charge varying between 0.1 nC - 100 nC, and laser spot size diameter at the cathode between 0.1 mm - 18 mm. The bunch length measurements were taken at different charge densities using a metallic screen and a Martin-Puplett interferometer to perform autocorrelation scans of the corresponding coherent transition radiation (CTR). A liquid helium-cooled 4K bolometer was used to register the interferometer signal. The experimental results are compared with Impact-T and OPAL-T numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF048
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THPMF050	High-Efficient XFELO Based on Optical Resonator with Self-Modulated Q-Factor	4172
	S.V. Kuzikov, A.V. Savilov, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia S.P. Antipov, S.V. Kuzikov Euclid TechLabs, LLC, Solon, Ohio, USA
	In this paper we describe an efficient XFELO having a new non-stationary out-coupling scheme. It consists of two undulator sections placed inside optical cavity. The first section is a conventional uniform undulator and the second one is a tapered undulator. At start time point X-ray radiation is mostly produced by the uniform section. Mirrors of XFELO's optical resonator are designed so that diffraction Q-factor reaches the highest value, i.e losses are near zero. As X-ray power increases the tapered undulator begins to contribute more to radiation power. However a portion of that power misses mirrors of the optical cavity, because those are tuned to confine radiation produced by the first undulator. This process establishes a steady state operation of the XFELO.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF050
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Paper

Title

Page

A Portable X-ray Source Based on Dielectric Accelerators

464

C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
S.P. Antipov, A. Kanareykin, R.A. Kostin
Euclid Beamlabs LLC, Bolingbrook, USA

Funding: The work has been supported by the U.S. Department of Homeland Security (DHS), Domestic Nuclear Detection Office (DNDO), under a competitively awarded contract No. HSHQDC-17-C-00007.
The portable low energy accelerator based X-ray sources have attractive applications in the non-destructive examination as a replacement of radiological gamma isotope sources. We are developing an inexpensive ultra-compact dielectric accelerator technology for low energy electron beams. The portability in the realm of this proposal is unprecedented ~ 1 ft3 volume with ~ 50 lbs of weight. The use of ceramics makes the transverse size of the accelerating waveguide comparable to that of a pencil. Because of this size reduction, additional weight reduction of shielding becomes possible. The article will report on the progress of this project.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML029

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TUPML006

Updates of the Argonne Cathode Test-stand

1542

J.H. Shao, M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.F. Power, C. Whiteford, E.E. Wisniewski, L.M. Zheng
ANL, Argonne, Illinois, USA
S.P. Antipov, G. Chen, E. Gomez, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
S.V. Baryshev
Michigan State University, East Lansing, Michigan, USA

The Argonne Cathode Test-stand (ACT) is a unique testbed to develop cathodes and to conduct fundamental surface study under ultra-high rf field (up to 700 MV/m with pin-shaped cathodes). The test-stand consists of an L-band 1.3 GHz single-cell photocathode rf gun and a field emission (FE) imaging system to locate emitters with a resolution of ∼20 𝜇m. In the recent upgrade, UV laser has been introduced to improve the imaging system and to significantly expand the ACT towards photoemission and laser-assisted field emission research. In addition, a load-lock system has been added to the beam line to expedite the cathode switching period. The paper will present details of the upgrade as well as experiments planned in the near future.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML006

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TUPML061

Study of Mean Transverse Energy of (N)UNCD with Tunable Laser Source

1677

SUSPF050

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

G. Chen
IIT, Chicago, Illinois, USA
G. Adhikari, W.A. Schroeder
UIC, Chicago, Illinois, USA
S.P. Antipov, C.-J. Jing, K. Kovi
Euclid TechLabs, LLC, Solon, Ohio, USA
S.V. Baryshev
ANL, Argonne, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: NSF grant No. NSF-1739150, DOE SBIR program grant No. DE-SC0013145, NSF grant No. PHYS-1535279, DOE Contract No. DE-AC02-06CH11357.
There is a strong motivation to develop and understand novel materials with the potential to be utilized as photocathodes, as these could have desirable photoemission properties for research and industrial applications. Nitrogen-incorporated ultrananocrystalline diamond ((N)UNCD) photocathodes have potential to become a material of choice for photocathode applications*. (N)UNCD has high quantum efficiency when processed in hydrogen plasma*, low surface roughness, and high electron conductivity through the bulk**. The mean transverse energy (MTE) was calculated for (N)UNCD thin films using the double-solenoid scan method. (N)UNCD thin film with thickness of 160nm was deposited on highly-doped silicon substrate. Studies of the MTE of a (N)UNCD sample were done using a tunable laser source with photon energies of 3.56 eV to 5.26 eV. These results are presented.
* K.J. Pérez Quintero et al., Appl. Phys. Lett. 105, 123103 (2014).
** S. Bhattacharyya et al., Appl. Phys. Lett. 79, 1441 (2001)

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WEPAF058

Detection of X-Rays and Charged Particles via Detuning of the Microwave Resonator

1958

S.P. Antipov
Euclid TechLabs, LLC, Solon, Ohio, USA
S.V. Kuzikov
Euclid Beamlabs LLC, Bolingbrook, USA
S. Stoupin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

Funding: DOE SBIR
Critically coupled microwave resonator is a finely balanced system, reflection at the resonance is virtually zero. Small changes in dielectric properties of resonator parts destroy this balance, small reflection can be detected from the resonator. This measurement is used in electron paramagnetic resonance studies. In this paper we discuss two accelerator - related applications of this technology. First is related to beam halo measurement taking advantage of high sensitivity of the microwave measurement. High energy particles crossing the diamond inside of a tuned resonator induce a weak conductivity in the sensing material. This small change results in resonator decoupling providing a signal proportional to a number of particles crossing the diamond plate. Second application considered is the x-ray flux monitoring. In this case it is x-ray induced photoconductivity which alters resonator coupling and produces a signal. Interestingly, sensing dielectric material embedded in a resonator can be a diamond or kapton window, refractive lens or part of a silicon monochromator. Thus an inevitable x-ray absorption on optical elements of the beamline is used to monitor x-ray flux online.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF058

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WEPAF060

Non-Invasive Bunch Length Diagnostics for High Intensity Beams

1964

S.V. Kuzikov, S.P. Antipov
Euclid TechLabs, LLC, Solon, Ohio, USA
S.V. Kuzikov, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

Modern particle accelerators utilize photoinjectors and compression schemes to produce short high peak current electron bunches for various applications like x-ray free electron lasers, high gradient beam driven acceleration and others. Bunch length detection is a desired diagnostics for such machines. In this paper we describe a non-invasive, real-time detector which can be retrofitted into an existing beamline and measure the bunch length in real time using interferometric methods. Diffraction radiation is the mechanism to be used to produce a measurable signal without intercepting the beam. This became possible as sensitivity of pyrodetectors improved over the years, while peak beam power grew. For high peak current beams there is a possibility of a single shot measurement. This can be done with a pair of closely placed vacuum breaks that create a spatial correlation of the generated signals which can be measured by a pyro-detector array or a THz camera. The bunch length is determined from the correlation data using an iterative beam profile recovery algorithm.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF060

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WEPMF068

Inexpensive Brazeless Accelerator Prototype

2528

S.P. Antipov, R.A. Kostin, S.V. Kuzikov
Euclid TechLabs, LLC, Solon, Ohio, USA
A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

Funding: DOE SBIR
A simple, inexpensive way to manufacture a standard radio frequency (RF) driven particle accelerator is presented. The simplification comes from two innovations: utilization of LCLS gun type RF design to avoid an expensive brazing process and copper plating of stainless steel that further reduces manufacturing cost. This is realized by a special structure design where accelerating structure cells are made out of copper plated stainless steel with knife edges and structure irises - copper disks acts also as gaskets for vacuum and RF seal. Besides the reduced cost, brazeless assembly allows integration of effective cooling and magnet optics elements into accelerator cells. Here we report on manufacturing and testing of brazeless accelerator prototype.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF068

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WEPMF069

High Shunt Impedance Accelerating Structure with Distributed Microwave Coupling

2531

S.P. Antipov, R.A. Kostin, S.V. Kuzikov
Euclid TechLabs, LLC, Solon, Ohio, USA
V.A. Dolgashev
SLAC, Menlo Park, California, USA

Funding: DOE SBIR
Conventional traveling wave or pi-phase advance standing wave structures use coupling of the microwave power through the beam pipe. This feature constrains the cavity shunt impedance (efficiency) to relatively small values. As microwave power flows through the accelerating cells in such structures, the probability of breakdown in high gradient operation is greatly increased. In this paper we present results from an accelerating structure prototype with distributed microwave coupling, an approach invented at SLAC. These structures include one or more parallel waveguides which are loaded by accelerating cavities. In this configuration accelerating cavities are fed independently and completely isolated at the beam pipe. Thus there is no microwave power flow through the accelerating cavity, making this geometry favorable for high gradient operation and maximizing the shunt impedance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF069

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THPMF011

Femtosecond Laser Ablation for Manufacturing of X-ray Lenses and Phase Corrector Plates

4057

S.P. Antipov
Euclid TechLabs, LLC, Solon, Ohio, USA
L. Assoufid, W.C. Grizolli, J. Qian, X. Shi
ANL, Argonne, Illinois, USA

Funding: DOE SBIR
The next generation light sources such as diffraction limited storage rings and high repetition rate free electron lasers (FELs) will generate X-ray beams with significantly increased peak and average brilliance. These future facilities will require X-ray optical components capable of handling large instantaneous and average power densities while tailoring the properties of the X-ray beams for a variety of scientific experiments. In this paper we report on research and development of a single crystal diamond compound refractive lens. Diamond lenses presented here are fabricated by fs-laser cutting and subsequent polishing. Grating interferometry measurement data of these lenses had been performed at the Advanced Photon Source (Argonne). Besides the lenses, we fabricated and tested several phase correction plates, a refractive elements designed to correct for cumulative X-ray beam aberrations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF011

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THPMF012

Tapered Flying Radiofrequency Undulator

4059

S.P. Antipov, S.V. Kuzikov, A. Liu
Euclid TechLabs, LLC, Solon, Ohio, USA
S.V. Kuzikov, A.V. Savilov, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

Funding: DOE SBIR DE-SC0017145
The x-ray free electron laser (x-FEL) efficiency, measured as a fraction of the electron beam power converted into light, is typically below 0.1% for most of the x-FEL facilities presently in operation. Undulator tapering techniques can be used to improve the conversion efficiency by 1-2 orders of magnitude. However at present there are no robust tapered undulator x-FEL schemes operating at 10% efficiency. In this paper we report on the development of tapered radiofrequency (RF) undulator. An RF undulator is a microwave waveguide in which strong RF field is excited that interacts with a charged particle beam forcing it to radiate coherent x-rays while undergoing a wiggling motion. RF undulators are attractive for use in x-FELs due to their large beam aperture and a short undulator period. Strongly tapered RF undulators (with tapering of a wavelength) due to non-resonant trapping regime allow keeping high overall XFEL efficiency being driven by laser plasma accelerated beams usually having high enough current but large energy spread (1-10%).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF012

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THPMF048

Bunch Length Measurements Using CTR at the AWA with Comparison to Simulation

4166

N.R. Neveu
IIT, Chicago, Illinois, USA
S.P. Antipov
Euclid TechLabs, LLC, Solon, Ohio, USA
A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA
J.G. Power, C. Whiteford, E.E. Wisniewski
ANL, Argonne, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: This work is funded by the DOE Office of Science, grant no. DE-SC0015479, and contract No. DE-AC02- 06CH11357.
In this paper we present electron bunch length measurements at the Argonne Wakefield Accelerator (AWA) photoinjector facility. The AWA accelerator has a large dynamic charge density range, with electron beam charge varying between 0.1 nC - 100 nC, and laser spot size diameter at the cathode between 0.1 mm - 18 mm. The bunch length measurements were taken at different charge densities using a metallic screen and a Martin-Puplett interferometer to perform autocorrelation scans of the corresponding coherent transition radiation (CTR). A liquid helium-cooled 4K bolometer was used to register the interferometer signal. The experimental results are compared with Impact-T and OPAL-T numerical simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF048

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THPMF050

High-Efficient XFELO Based on Optical Resonator with Self-Modulated Q-Factor

4172

S.V. Kuzikov, A.V. Savilov, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia
S.P. Antipov, S.V. Kuzikov
Euclid TechLabs, LLC, Solon, Ohio, USA

In this paper we describe an efficient XFELO having a new non-stationary out-coupling scheme. It consists of two undulator sections placed inside optical cavity. The first section is a conventional uniform undulator and the second one is a tapered undulator. At start time point X-ray radiation is mostly produced by the uniform section. Mirrors of XFELO's optical resonator are designed so that diffraction Q-factor reaches the highest value, i.e losses are near zero. As X-ray power increases the tapered undulator begins to contribute more to radiation power. However a portion of that power misses mirrors of the optical cavity, because those are tuned to confine radiation produced by the first undulator. This process establishes a steady state operation of the XFELO.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF050

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