IPAC2015 - List of Authors (Schroeder, C.B.)

Paper	Title	Page
TUYC2	Multi-GeV Plasma Acceleration Results at BELLA	1319
	A.J. Gonsalves, C. Benedetti, S.S. Bulanov, J. Daniels, E. Esarey, C.G.R. Geddes, H.S. Mao, D.E. Mittelberger, K. Nakamura, C.B. Schroeder, C. Tóth, J. van Tilborg LBNL, Berkeley, California, USA W. Leemans UCB, Berkeley, California, USA
	Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231 Laser-plasma accelerators (LPAs)* are being investigated as a compact driver for light sources and high-energy linear colliders. Recently 2 GeV beams were generated by focusing ≈ 100 J laser pulses onto a gas target. We report here on the generation of beams with energy up to 4.2 GeV using 16 J of laser pulse energy at the BErkeley Lab Laser Accelerator (BELLA). This was achieved by using laser pulses of high spatial and temporal quality coupled to a pre-formed capillary discharge waveguide of length 9 cm. The waveguide (in conjunction with self-guiding) allowed for mitigation of diffraction. High spatial quality (Strehl ratio at focus 0.8±0.1) was achieved using a deformable mirror placed before the focusing optic. The dominant contribution to the non-Gaussian content of the focal spot was the near-field intensity profile. For maximum efficiency high-power femtosecond systems employ super-Gaussian near-field profiles of the form I(r)∝e^-2(r/w^N), where I is the intensity, r is the radial coordinate, w is the spot size, and N is the order. Compared with Gaussian laser pulses where N=2, pulses from the BELLA laser system had N=10. Simulations showed that an increased contribution of self-guiding was required to effectively confine the laser energy for optimum acceleration and mitigation of damage to the capillary waveguide. Through appropriate choice of plasma density electron beams with energy up to 4.2 GeV were observed. In this regime the electron beam angular fluctuations were > 2 mrad rms, caused in part by errors in waveguide alignment and by laser-induced damage to the capillary that introduces plasma asymmetry. Improved alignment of the waveguide and mitigation of capillary damage allowed for reduction in angular fluctuations to 0.6 mrad rms. The electron beams had energy of 2.7±0.1 GeV, charge of 150 pC, and divergence less than 1 mrad. E. Esarey, et al., Rev. Mod. Phys. 81, 1229 (2009) X. Wang, et al., Nat. Communications 4, 1988 (2013) * W. P. Leemans, et al., Phys. Rev. Lett. 113, 245002 (2014)
	Slides TUYC2 [13.023 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUYC2
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WEPWA005	Simulations Study for Self-Modulation Experiment at PITZ	2496
	G. Pathak, F.J. Grüner Uni HH, Hamburg, Germany C. Benedetti, C.B. Schroeder LBNL, Berkeley, California, USA M. Groß, F. Stephan DESY Zeuthen, Zeuthen, Germany A. Martinez de la Ossa, T.J. Mehrling, J. Osterhoff DESY, Hamburg, Germany
	Self-modulation (SM) of proton beams in plasma has recently gained interest in context with the ongoing PWFA experiment of the AWAKE collaboration at CERN. Instrumental for that experiment is the SM of a proton beam to generate bunchlets for resonant wave excitation and efficient acceleration. A fundamental understanding of the underlying physics is vital, and hence an independent experiment has been set up at the beamline of the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ), to study the SM of electron beams in a plasma. This contribution presents simulation results on SM experiments at PITZ using the particle-in-cell code HiPACE. The simulation study is crucial to optimize the beam and plasma parameters for the experiment. Of particular interest is the energy modulation imprinted onto the beam by means of the generated wakefields in the plasma. With the support of simulations the observation of this information in the experiment can be used to deduce key properties of the accelerating electric fields such as their magnitude and their phase velocity, both of significant importance for the design of self-modulated plasma-based acceleration experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA005
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Multi-GeV Plasma Acceleration Results at BELLA

1319

A.J. Gonsalves, C. Benedetti, S.S. Bulanov, J. Daniels, E. Esarey, C.G.R. Geddes, H.S. Mao, D.E. Mittelberger, K. Nakamura, C.B. Schroeder, C. Tóth, J. van Tilborg
LBNL, Berkeley, California, USA
W. Leemans
UCB, Berkeley, California, USA

Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231
Laser-plasma accelerators (LPAs)* are being investigated as a compact driver for light sources and high-energy linear colliders. Recently 2 GeV beams were generated by focusing ≈ 100 J laser pulses onto a gas target**. We report here on the generation of beams with energy up to 4.2 GeV using 16 J of laser pulse energy at the BErkeley Lab Laser Accelerator (BELLA)***. This was achieved by using laser pulses of high spatial and temporal quality coupled to a pre-formed capillary discharge waveguide of length 9 cm. The waveguide (in conjunction with self-guiding) allowed for mitigation of diffraction. High spatial quality (Strehl ratio at focus 0.8±0.1) was achieved using a deformable mirror placed before the focusing optic. The dominant contribution to the non-Gaussian content of the focal spot was the near-field intensity profile. For maximum efficiency high-power femtosecond systems employ super-Gaussian near-field profiles of the form I(r)∝e^-2(r/w^N), where I is the intensity, r is the radial coordinate, w is the spot size, and N is the order. Compared with Gaussian laser pulses where N=2, pulses from the BELLA laser system had N=10. Simulations showed that an increased contribution of self-guiding was required to effectively confine the laser energy for optimum acceleration and mitigation of damage to the capillary waveguide. Through appropriate choice of plasma density electron beams with energy up to 4.2 GeV were observed. In this regime the electron beam angular fluctuations were > 2 mrad rms, caused in part by errors in waveguide alignment and by laser-induced damage to the capillary that introduces plasma asymmetry. Improved alignment of the waveguide and mitigation of capillary damage allowed for reduction in angular fluctuations to 0.6 mrad rms. The electron beams had energy of 2.7±0.1 GeV, charge of 150 pC, and divergence less than 1 mrad.
* E. Esarey, et al., Rev. Mod. Phys. 81, 1229 (2009)
** X. Wang, et al., Nat. Communications 4, 1988 (2013)
*** W. P. Leemans, et al., Phys. Rev. Lett. 113, 245002 (2014)

Slides TUYC2 [13.023 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUYC2

Export •

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

WEPWA005

Simulations Study for Self-Modulation Experiment at PITZ

2496

G. Pathak, F.J. Grüner
Uni HH, Hamburg, Germany
C. Benedetti, C.B. Schroeder
LBNL, Berkeley, California, USA
M. Groß, F. Stephan
DESY Zeuthen, Zeuthen, Germany
A. Martinez de la Ossa, T.J. Mehrling, J. Osterhoff
DESY, Hamburg, Germany

Self-modulation (SM) of proton beams in plasma has recently gained interest in context with the ongoing PWFA experiment of the AWAKE collaboration at CERN. Instrumental for that experiment is the SM of a proton beam to generate bunchlets for resonant wave excitation and efficient acceleration. A fundamental understanding of the underlying physics is vital, and hence an independent experiment has been set up at the beamline of the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ), to study the SM of electron beams in a plasma. This contribution presents simulation results on SM experiments at PITZ using the particle-in-cell code HiPACE. The simulation study is crucial to optimize the beam and plasma parameters for the experiment. Of particular interest is the energy modulation imprinted onto the beam by means of the generated wakefields in the plasma. With the support of simulations the observation of this information in the experiment can be used to deduce key properties of the accelerating electric fields such as their magnitude and their phase velocity, both of significant importance for the design of self-modulated plasma-based acceleration experiments.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA005

Export •

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