Laser-heated capillary discharge plasma waveguides for electron acceleration to 8 GeV

Journal Article · Tue May 05 00:00:00 EDT 2020 · Physics of Plasmas

DOI:https://doi.org/10.1063/5.0002769· OSTI ID:1780739

Gonsalves, A. J. ^[1]; Nakamura, K. ^[1]; Benedetti, C. ^[1]; Pieronek, C. V. ^[2]; Steinke, S. ^[1]; Bin, J. H. ^[1]; Bulanov, S. S. ^[1]; van Tilborg, J. ^[1]; Geddes, C. G. R. ^[1]; Schroeder, C. B. ^[2]; Daniels, J. ^[1]; Tóth, Cs ^[1]; Obst-Huebl, L. ^[1]; van den Berg, R. G. W. ^[3]; Bagdasarov, G. ^[4]; Bobrova, N. ^[5]; Gasilov, V. ^[4]; Korn, G. ^[6]; Sasorov, P. ^[7]; Leemans, W. P. ^[2] ; Esarey, E. ^[1]

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1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
3. University of Eindhoven (The Netherlands)
4. Russian Academy of Sciences (RAS), Moscow (Russia); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russia)
5. Russian Academy of Sciences (RAS), Moscow (Russia)
6. Institute of Physics ASCR, v.v.i. (FZU), Prague (Czech Republic)
7. Russian Academy of Sciences (RAS), Moscow (Russia); Institute of Physics ASCR, v.v.i. (FZU), Prague (Czech Republic)

A plasma channel created by the combination of a capillary discharge and inverse Bremsstrahlung laser heating enabled the generation of electron bunches with energy up to 7.8 GeV in a laser-driven plasma accelerator. The capillary discharge created an initial plasma channel and was used to tune the plasma temperature, which optimized laser heating. Although optimized colder initial plasma temperatures reduced the ionization degree, subsequent ionization from the heater pulse created a fully ionized plasma on-axis. The heater pulse duration was chosen to be longer than the hydrodynamic timescale of ≈ 1 ns, such that later temporal slices were more efficiently guided by the channel created by the front of the pulse. Here, simulations are presented which show that this thermal self-guiding of the heater pulse enabled channel formation over 20 cm. The post-heated channel had lower on-axis density and increased focusing strength compared to relying on the discharge alone, which allowed for guiding of relativistically intense laser pulses with a peak power of 0.85 PW and wakefield acceleration over 15 diffraction lengths. Electrons were injected into the wake in multiple buckets and times, leading to several electron bunches with different peak energies. To create single electron bunches with low energy spread, experiments using localized ionization injection inside a capillary discharge waveguide were performed. A single injected bunch with energy 1.6 GeV, charge 38 pC, divergence 1 mrad, and relative energy spread below 2% full-width half-maximum was produced in a 3.3 cm-long capillary discharge waveguide. This development shows promise for mitigation of energy spread and future high efficiency staged acceleration experiments.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
• Sponsoring Organization: Alexander von Humboldt Foundation; European Regional Development Fund (ERDF); National Science Foundation (NSF); USDOE; USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1780739
• Alternate ID(s): OSTI ID: 1617256
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 27; ISSN 1070-664X
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Electron beams
Laser applications
Laser plasma interactions
Magnetohydrodynamics
Plasma acceleration
Plasma diagnostics
Plasma discharges
Plasma properties and parameters
Plasma temperature
Waveguides