PAC2013 - List of Authors (Simakov, E.I.)

Paper	Title	Page
MOPAC23	Particle-In-Cell Modeling of Dielectric Wakefield Accelerator	114
	C. Huang, T.J. Kwan, D.Y. Shchegolkov, E.I. Simakov LANL, Los Alamos, New Mexico, USA
	Funding: This work is supported by the U.S. Department of Energy through the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory. Dielectric Wakefield Accelerator (DWA) holds the promise as an upgrade for the X-ray free electron laser of the proposed Los Alamos Matter-Radiation Interactions in Extremes signature facility. Our proof-of-concept DWA experiment aims to produce an acceleration gradient > 100 MV/m with < 0.1% induced beam energy spread. We design a 2.5ps double-triangular drive bunch and a trapezoidal witness bunch through the use of an electron beam mask followed by an Emittance Exchanger (EEX). To understand the DWA performance under transient dynamics, non-perfect EEX and other non-ideal effects, we use the Particle-In-Cell codes Merlin and LSP in 2D cylindrical and 3D geometries, respectively, to model our design. The benchmark shows good agreements with analytic theory on the longitudinal wakefield and the transformer ratio. Our simulations also indicate that longitudinal electric profile is highly insensitive to beam energy, radial distribution and emittance. We have investigated the transverse uniformity of the accelerating field and the effects of beam misalignment with radial beam offset. Full-scale simulation results for the planned experiment will be presented and discussed.

MOPAC24	Beam Pulse Shaping Experiments for Uniform High Gradient Dielectric Wakefield Acceleration	117
	D.Y. Shchegolkov, E.I. Simakov LANL, Los Alamos, New Mexico, USA S.P. Antipov Euclid TechLabs, LLC, Solon, Ohio, USA S.P. Antipov ANL, Argonne, USA M.G. Fedurin, C. Swinson BNL, Upton, Long Island, New York, USA
	Funding: Work is supported by the U.S. Department of Energy (DOE) through the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory. Dielectric wakefield accelerators (DWA) can produce high accelerating gradients and are planned to be used as afterburners for the accelerators of future free electron lasers (FELs) such as X-ray FEL of the proposed Matter-Radiation Interactions in Extremes (MaRIE) experimental facility at LANL. With a double triangular drive bunch DWAs can produce a high transformer ratio. Also, by slightly customizing the time shape of the accelerated bunch it is possible to achieve high gradient uniformity along the accelerated bunch resulting in low induced energy spread. We plan to test a DWA which would incorporate all those benefits. We are going to obtain a desired current profile of the main and drive bunches from a single large-charge beam using one of the known pulse shaping techniques employing a mask.* * We will report our recent beam shaping experiments at BNL for a transformer ratio test. We used a 58 MeV energy chirped electron beam and a single dogleg with a beam mask inserted in a region where the beam transverse size was dominated by the correlated energy chirp. Both measurement results and Elegant simulation data will be presented. P. Emma, Z. Huang , et al, Phys Rev ST Accel Beams 9, 100702 (2006). P. Muggli, V. Yakimenko, et al, PRL 101, 054801 (2008). **D. Xiang and A. Chao, SLAC-PUB-14428 (2011).

MOPAC25	Update on Fabrication and Tuning of the Photonic Band Gap Accelerating Structure for the Wakefield Experiment	120
	E.I. Simakov, S. Arsenyev, R.L. Edwards, S. Elson, C.E. Heath, D. C. Lizon, W.P. Romero LANL, Los Alamos, New Mexico, USA S. Arsenyev MIT/PSFC, Cambridge, Massachusetts, USA
	Funding: This work is supported by the U.S. Department of Energy (DOE) Office of Science Early Career Research Program. We designed an experiment to conduct a thorough investigation of higher order mode spectrum in a room-temperature traveling-wave photonic band gap (PBG) accelerating structure at 11.7 GHz. It has been long recognized that PBG structures have great potential in reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in room-temperature PBG structures was conducted at MIT in 2005. Since then, the importance of that device has been recognized by many research institutions. However, the full experimental characterization of the wakefield spectrum in a beam test has not been performed to date. The Argonne Wakefield Accelerator (AWA) test facility at the Argonne National Laboratory represents a perfect site where this evaluation could be conducted with a single high charge electron bunch and with a train of bunches. We present the design of the accelerating structure that will be tested at AWA in the near future. We will also present the results of fabrication and tuning of PBG cells and other components and the initial cold-testing of the traveling-wave accelerating structure. We will discuss the plan for the wakefield experiment.

TUPMA13	Shaping Electron Bunches for Ultra-bright Electron Beam Acceleration in Dielectric Loaded Waveguides	613
	E.I. Simakov, C. Huang, T.J. Kwan, D.Y. Shchegolkov LANL, Los Alamos, New Mexico, USA
	Funding: This work is supported by the U.S. Department of Energy through the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory. We present the design of an Emittance Exchanger (EEX) which is employed to generate a pair of a double-triangular drive bunch and a trapezoidal witness bunch for a Dielectric Wakefield Accelerator (DWA). We consider the concept of a high-brightness DWA with the gradient of above 100 MV/m and less than 0.1% induced energy spread in the accelerated beam as a possible afterburner for the proposed Los Alamos Matter-Radiation Interactions in Extremes (MaRIE) signature facility. Scoping studies have identified large induced energy spreads as the major cause of beam quality degradation in high-gradient advanced accelerator technologies. Among advanced accelerator technologies, DWAs hold significant advantages over plasma wakefield accelerators due to the elimination of plasma-induced effects, the fact that having the wakefield in vacuum ensures linearity, and their higher technological maturity. We will present simulations with Elegant of the possible EEX beamline taking into account non-linear effects, coherent synchrotron radiation and longitudinal space charge. Possibilities for producing ideal beam shapes to demonstrate low induced energy spread in a DWA will be discussed.

WEPAC33	Results of the New High Power Tests of Superconducting Photonic Band Gap Structure Cells	850
	E.I. Simakov, S. Arsenyev, W.B. Haynes, S.S. Kurennoy, D. C. Lizon, J.F. O'Hara, E.R. Olivas, D.Y. Shchegolkov, N.A. Suvorova, T. Tajima LANL, Los Alamos, New Mexico, USA S. Arsenyev MIT/PSFC, Cambridge, Massachusetts, USA C.H. Boulware, T.L. Grimm Niowave, Inc., Lansing, Michigan, USA
	Funding: This work is supported by the Department of Defense High Energy Laser Joint Technology Office through the Office of Naval Research. We present an update on the 2.1 GHz superconducting rf (SRF) photonic band gap (PBG) resonator experiment in Los Alamos. The new SRF PBG cell was designed with the particular emphasis on changing the shape of PBG rods to reduce the peak magnetic fields and at the same time to preserve its effectiveness for suppression of the higher order modes (HOMs). The new PBG cells have great potential for outcoupling long-range wakefields in SRF accelerator structures without affecting the fundamental accelerating mode. Using PBG structures in superconducting particle accelerators will allow operation at higher frequencies and moving forward to significantly higher beam luminosities thus leading towards a completely new generation of colliders for high energy physics. Here we report the results of our efforts to fabricate 2.1 GHz PBG cells with elliptical rods and to test them with high power in a liquid helium bath at the temperature of 2 Kelvin. The high gradient performance of the cells will be evaluated and the results will be compared to electromagnetic and thermal simulations.

WEPAC34	Update on the Design of a Five-Cell Superconducting RF Module with a PBG Coupler Cell	853
	S. Arsenyev MIT/PSFC, Cambridge, Massachusetts, USA E.I. Simakov LANL, Los Alamos, New Mexico, USA
	Funding: This work is supported by the U.S. Department of Energy (DOE) Office of Science Early Career Research Program. We present a complete design of the 5-cell superconducting accelerating module incorporating a Photonic Band Gap (PBG) cell with couplers. The purpose of the PBG cell is to achieve better Higher Order Mode (HOM) damping which is vital for preserving the quality of high-current electron beams in novel linear accelerators. The PBG technology can therefore be used for X-band free electron lasers. We first discuss the engineering aspects of incorporating a PBG cell in a superconducting PBG module. The main concern is to ensure the equal probability of quench is in each of the five cells, which leads to significant geometry modifications. We then present the simulation data on the HOM damping. Particularly, we calculate the external quality factors for the 10 most dangerous HOMs for this particular structure. Performance of different couplers and different modifications of the PBG lattice are discussed. Thermal analysis of the structure is also discussed briefly.

Paper

Title

Page

Particle-In-Cell Modeling of Dielectric Wakefield Accelerator

114

C. Huang, T.J. Kwan, D.Y. Shchegolkov, E.I. Simakov
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by the U.S. Department of Energy through the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory.
Dielectric Wakefield Accelerator (DWA) holds the promise as an upgrade for the X-ray free electron laser of the proposed Los Alamos Matter-Radiation Interactions in Extremes signature facility. Our proof-of-concept DWA experiment aims to produce an acceleration gradient > 100 MV/m with < 0.1% induced beam energy spread. We design a 2.5ps double-triangular drive bunch and a trapezoidal witness bunch through the use of an electron beam mask followed by an Emittance Exchanger (EEX). To understand the DWA performance under transient dynamics, non-perfect EEX and other non-ideal effects, we use the Particle-In-Cell codes Merlin and LSP in 2D cylindrical and 3D geometries, respectively, to model our design. The benchmark shows good agreements with analytic theory on the longitudinal wakefield and the transformer ratio. Our simulations also indicate that longitudinal electric profile is highly insensitive to beam energy, radial distribution and emittance. We have investigated the transverse uniformity of the accelerating field and the effects of beam misalignment with radial beam offset. Full-scale simulation results for the planned experiment will be presented and discussed.

MOPAC24

Beam Pulse Shaping Experiments for Uniform High Gradient Dielectric Wakefield Acceleration

117

D.Y. Shchegolkov, E.I. Simakov
LANL, Los Alamos, New Mexico, USA
S.P. Antipov
Euclid TechLabs, LLC, Solon, Ohio, USA
S.P. Antipov
ANL, Argonne, USA
M.G. Fedurin, C. Swinson
BNL, Upton, Long Island, New York, USA

Funding: Work is supported by the U.S. Department of Energy (DOE) through the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory.
Dielectric wakefield accelerators (DWA) can produce high accelerating gradients and are planned to be used as afterburners for the accelerators of future free electron lasers (FELs) such as X-ray FEL of the proposed Matter-Radiation Interactions in Extremes (MaRIE) experimental facility at LANL. With a double triangular drive bunch DWAs can produce a high transformer ratio. Also, by slightly customizing the time shape of the accelerated bunch it is possible to achieve high gradient uniformity along the accelerated bunch resulting in low induced energy spread. We plan to test a DWA which would incorporate all those benefits. We are going to obtain a desired current profile of the main and drive bunches from a single large-charge beam using one of the known pulse shaping techniques employing a mask.* ** *** We will report our recent beam shaping experiments at BNL for a transformer ratio test. We used a 58 MeV energy chirped electron beam and a single dogleg with a beam mask inserted in a region where the beam transverse size was dominated by the correlated energy chirp. Both measurement results and Elegant simulation data will be presented.
*P. Emma, Z. Huang , et al, Phys Rev ST Accel Beams 9, 100702 (2006).
**P. Muggli, V. Yakimenko, et al, PRL 101, 054801 (2008).
***D. Xiang and A. Chao, SLAC-PUB-14428 (2011).

MOPAC25

Update on Fabrication and Tuning of the Photonic Band Gap Accelerating Structure for the Wakefield Experiment

120

E.I. Simakov, S. Arsenyev, R.L. Edwards, S. Elson, C.E. Heath, D. C. Lizon, W.P. Romero
LANL, Los Alamos, New Mexico, USA
S. Arsenyev
MIT/PSFC, Cambridge, Massachusetts, USA

Funding: This work is supported by the U.S. Department of Energy (DOE) Office of Science Early Career Research Program.
We designed an experiment to conduct a thorough investigation of higher order mode spectrum in a room-temperature traveling-wave photonic band gap (PBG) accelerating structure at 11.7 GHz. It has been long recognized that PBG structures have great potential in reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in room-temperature PBG structures was conducted at MIT in 2005. Since then, the importance of that device has been recognized by many research institutions. However, the full experimental characterization of the wakefield spectrum in a beam test has not been performed to date. The Argonne Wakefield Accelerator (AWA) test facility at the Argonne National Laboratory represents a perfect site where this evaluation could be conducted with a single high charge electron bunch and with a train of bunches. We present the design of the accelerating structure that will be tested at AWA in the near future. We will also present the results of fabrication and tuning of PBG cells and other components and the initial cold-testing of the traveling-wave accelerating structure. We will discuss the plan for the wakefield experiment.

TUPMA13

Shaping Electron Bunches for Ultra-bright Electron Beam Acceleration in Dielectric Loaded Waveguides

613

E.I. Simakov, C. Huang, T.J. Kwan, D.Y. Shchegolkov
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by the U.S. Department of Energy through the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory.
We present the design of an Emittance Exchanger (EEX) which is employed to generate a pair of a double-triangular drive bunch and a trapezoidal witness bunch for a Dielectric Wakefield Accelerator (DWA). We consider the concept of a high-brightness DWA with the gradient of above 100 MV/m and less than 0.1% induced energy spread in the accelerated beam as a possible afterburner for the proposed Los Alamos Matter-Radiation Interactions in Extremes (MaRIE) signature facility. Scoping studies have identified large induced energy spreads as the major cause of beam quality degradation in high-gradient advanced accelerator technologies. Among advanced accelerator technologies, DWAs hold significant advantages over plasma wakefield accelerators due to the elimination of plasma-induced effects, the fact that having the wakefield in vacuum ensures linearity, and their higher technological maturity. We will present simulations with Elegant of the possible EEX beamline taking into account non-linear effects, coherent synchrotron radiation and longitudinal space charge. Possibilities for producing ideal beam shapes to demonstrate low induced energy spread in a DWA will be discussed.

WEPAC33

Results of the New High Power Tests of Superconducting Photonic Band Gap Structure Cells

850

E.I. Simakov, S. Arsenyev, W.B. Haynes, S.S. Kurennoy, D. C. Lizon, J.F. O'Hara, E.R. Olivas, D.Y. Shchegolkov, N.A. Suvorova, T. Tajima
LANL, Los Alamos, New Mexico, USA
S. Arsenyev
MIT/PSFC, Cambridge, Massachusetts, USA
C.H. Boulware, T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA

Funding: This work is supported by the Department of Defense High Energy Laser Joint Technology Office through the Office of Naval Research.
We present an update on the 2.1 GHz superconducting rf (SRF) photonic band gap (PBG) resonator experiment in Los Alamos. The new SRF PBG cell was designed with the particular emphasis on changing the shape of PBG rods to reduce the peak magnetic fields and at the same time to preserve its effectiveness for suppression of the higher order modes (HOMs). The new PBG cells have great potential for outcoupling long-range wakefields in SRF accelerator structures without affecting the fundamental accelerating mode. Using PBG structures in superconducting particle accelerators will allow operation at higher frequencies and moving forward to significantly higher beam luminosities thus leading towards a completely new generation of colliders for high energy physics. Here we report the results of our efforts to fabricate 2.1 GHz PBG cells with elliptical rods and to test them with high power in a liquid helium bath at the temperature of 2 Kelvin. The high gradient performance of the cells will be evaluated and the results will be compared to electromagnetic and thermal simulations.

WEPAC34

Update on the Design of a Five-Cell Superconducting RF Module with a PBG Coupler Cell

853

S. Arsenyev
MIT/PSFC, Cambridge, Massachusetts, USA
E.I. Simakov
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by the U.S. Department of Energy (DOE) Office of Science Early Career Research Program.
We present a complete design of the 5-cell superconducting accelerating module incorporating a Photonic Band Gap (PBG) cell with couplers. The purpose of the PBG cell is to achieve better Higher Order Mode (HOM) damping which is vital for preserving the quality of high-current electron beams in novel linear accelerators. The PBG technology can therefore be used for X-band free electron lasers. We first discuss the engineering aspects of incorporating a PBG cell in a superconducting PBG module. The main concern is to ensure the equal probability of quench is in each of the five cells, which leads to significant geometry modifications. We then present the simulation data on the HOM damping. Particularly, we calculate the external quality factors for the 10 most dangerous HOMs for this particular structure. Performance of different couplers and different modifications of the PBG lattice are discussed. Thermal analysis of the structure is also discussed briefly.