Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

High-efficiency acceleration of an electron beam in a plasma wakefield accelerator


High-efficiency acceleration of charged particle beams at high gradients of energy gain per unit length is necessary to achieve an affordable and compact high-energy collider. The plasma wakefield accelerator is one concept1,2,3 being developed for this purpose. In plasma wakefield acceleration, a charge-density wake with high accelerating fields is driven by the passage of an ultra-relativistic bunch of charged particles (the drive bunch) through a plasma4,5,6. If a second bunch of relativistic electrons (the trailing bunch) with sufficient charge follows in the wake of the drive bunch at an appropriate distance, it can be efficiently accelerated to high energy. Previous experiments using just a single 42-gigaelectronvolt drive bunch have accelerated electrons with a continuous energy spectrum and a maximum energy of up to 85 gigaelectronvolts from the tail of the same bunch in less than a metre of plasma7. However, the total charge of these accelerated electrons was insufficient to extract a substantial amount of energy from the wake. Here we report high-efficiency acceleration of a discrete trailing bunch of electrons that contains sufficient charge to extract a substantial amount of energy from the high-gradient, nonlinear plasma wakefield accelerator. Specifically, we show the acceleration of about 74 picocoulombs of charge contained in the core of the trailing bunch in an accelerating gradient of about 4.4 gigavolts per metre. These core particles gain about 1.6 gigaelectronvolts of energy per particle, with a final energy spread as low as 0.7 per cent (2.0 per cent on average), and an energy-transfer efficiency from the wake to the bunch that can exceed 30 per cent (17.7 per cent on average). This acceleration of a distinct bunch of electrons containing a substantial charge and having a small energy spread with both a high accelerating gradient and a high energy-transfer efficiency represents a milestone in the development of plasma wakefield acceleration into a compact and affordable accelerator technology.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Three-dimensional particle-in-cell simulation of beam-driven plasma wakefield interaction.
Figure 2: Energetically dispersed beam profiles.
Figure 3: Spatially integrated electron beam spectra from the data set.
Figure 4: Energy-transfer efficiency dependence on wake loading.

Similar content being viewed by others


  1. Chen, P., Dawson, J., Huff, R. & Katsouleas, T. Acceleration of electrons by the interaction of a bunched electron beam with a plasma. Phys. Rev. Lett. 54, 693–696 (1985)

    Article  CAS  ADS  PubMed  Google Scholar 

  2. Ruth, R., Chao, A., Morton, P. & Wilson, P. A plasma wake field accelerator. Particle Accelerators 17, 171–189 (1985)

    CAS  Google Scholar 

  3. Esarey, E., Schroeder, C. B. & Leemans, W. P. Physics of laser-driven plasma-based electron accelerators. Rev. Mod. Phys. 81, 1229–1285 (2009)

    Article  CAS  ADS  Google Scholar 

  4. Joshi, C. & Katsouleas, T. Plasma accelerators at the energy frontier and on tabletops. Phys. Today 56, 47–53 (2003)

    Article  CAS  Google Scholar 

  5. Bingham, R., Mendonca, J. & Shukla, P. Plasma based charged-particle accelerators. Plasma Phys. Contr. Fusion 46, R1 (2004)

    Article  CAS  ADS  Google Scholar 

  6. Caldwell, A., Lotov, K., Pukhov, A. & Simon, F. Proton-driven plasma-wakefield acceleration. Nature Phys. 5, 363–367 (2009)

    Article  CAS  ADS  Google Scholar 

  7. Blumenfeld, I. et al. Energy doubling of 42 GeV electrons in a metre-scale plasma wakefield accelerator. Nature 445, 741–744 (2007)

    Article  CAS  ADS  Google Scholar 

  8. Lu, W., Huang, C., Zhou, M., Mori, W. B. & Katsouleas, T. Nonlinear theory for relativistic plasma wakefields in the blowout regime. Phys. Rev. Lett. 96, 165002 (2006)

    Article  CAS  ADS  PubMed  Google Scholar 

  9. Huang, C. et al. QuickPIC: a highly efficient fully parallelized PIC code for plasma-based acceleration. J. Phys. Conf. Ser. 46, 190–199 (2006)

    Article  ADS  Google Scholar 

  10. An, W., Decyk, V. K., Mori, W. B. & Antonsen, T. M., Jr An improved iteration loop for the three dimensional quasi-static particle-in-cell algorithm: QuickPIC. J. Comput. Phys. 250, 165–177 (2013)

    Article  MathSciNet  ADS  Google Scholar 

  11. Hogan, M. et al. Multi-GeV energy gain in a plasma-wakefield accelerator. Phys. Rev. Lett. 95, 054802 (2005)

    Article  CAS  ADS  PubMed  Google Scholar 

  12. Muggli, P. et al. Meter-scale plasma-wakefield accelerator driven by a matched electron beam. Phys. Rev. Lett. 93, 014802 (2004)

    Article  ADS  Google Scholar 

  13. Barov, N. et al. Ultra high-gradient energy loss by a pulsed electron beam in a plasma. IEEE Proc. (2001 Particle Accelerator Conf.) 1, 126–128 (2001)

    Article  CAS  ADS  Google Scholar 

  14. Katsouleas, T. Physical mechanisms in the plasma wake-field accelerator. Phys. Rev. A 33, 2056–2064 (1986)

    Article  CAS  ADS  Google Scholar 

  15. Tzoufras, M. et al. Beam loading in the nonlinear regime of plasma-based acceleration. Phys. Rev. Lett. 101, 145002 (2008)

    Article  CAS  ADS  Google Scholar 

  16. Rosenzweig, J. B. et al. Experimental observation of plasma wake-field acceleration. Phys. Rev. Lett. 61, 98–101 (1988)

    Article  CAS  ADS  PubMed  Google Scholar 

  17. Muggli, P. et al. Photo-ionized lithium source for plasma accelerator applications. IEEE Trans. (Plasma Sci.) 27, 791–799 (1999)

    Article  CAS  ADS  Google Scholar 

  18. Green, S. Z. et al. Laser ionized preformed plasma at FACET. Plasma Phys. Contr. Fusion 56, 084011 (2014)

    Article  ADS  Google Scholar 

  19. Adli, E. et al. A beam driven plasma-wakefield linear collider: from Higgs factory to multi-TeV. In Electronic Proceedings of the Snowmass 2013 Community Study on the Future of High-Energy Physics (2013)

Download references


The FACET E200 plasma wakefield acceleration experiment was built and has been operated with funding from the United States Department of Energy. Work at SLAC was supported by DOE contract DE-AC02-76SF00515 and also through the Research Council of Norway. Work at UCLA was supported by DOE contracts DE-FG02-92-ER40727 and DE-SC0010064. Simulations were performed on the UCLA Hoffman2 and Dawson2 computers and on Blue Waters through NSF OCI-1036224. Simulation work at UCLA was supported by DOE contracts DE-SC0008491 and DE-SC0008316, and NSF contracts ACI-1339893 and PHY-0960344. The work of W.L. was partially supported by NSFC 11175102, the Thousand Young Talents Program and the Tsinghua University Initiative Scientific Research Program.

Author information

Authors and Affiliations



All authors contributed extensively to the work presented in this paper.

Corresponding author

Correspondence to M. Litos.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 FACET experimental area schematic.

Electron beam line features: a, beam notching device, b, transverse deflecting structure, c, initial spectrometer, d, final-focus quadrupole magnets, e, lithium plasma ionization laser, f, lithium vapour column, g, spectrometer imaging quadrupole magnets, h, spectrometer dipole magnet, and i, Cherenkov and phosphor screens. Bend dipole magnets in the ‘W’-shaped chicane are each labelled ‘D’. The arrow beneath the e symbol indicates the electron beam’s direction of motion (left to right).

Extended Data Figure 2 Measured longitudinal profile of two-bunch beam.

Image of a typical two-bunch beam streaked onto a profile monitor screen by the transverse deflecting radio-frequency structure (Extended Data Fig. 1b). The drive bunch appears on the right-hand side. Overlaid on the image is the projected longitudinal profile (red line). The left (x) and top (y) axes show the transverse dimensions of the streaked beam on the profile monitor screen, while the colour axis indicates the charge density of the transverse profile. The bottom (z) axis shows the streaked dimension (y) with the appropriate scaling factor applied to give the corresponding longitudinal coordinate. The right axis shows the linear charge density corresponding to the projected longitudinal profile.

Extended Data Figure 3 Lithium vapour column density profile.

The profile of the neutral vapour pressure density of the lithium vapour column deduced from the measured temperature profile (temperature versus relative distance of insertion of a thermocouple probe) along the heat pipe oven is shown as the blue line. The simple fit used to describe the density profile in our model is shown as the red line.

Extended Data Figure 4 Fit to accelerated charge.

The blue line is the spectral projection of the same data shot shown in Fig. 2c and d. The green line is a fit to the data using a half-Gaussian tail (cyan line) to account for the diffuse, high-angular-divergence accelerated charge plus a full, asymmetric Gaussian (red) used to describe the core of the accelerated trailing bunch after subtracting the half-Gaussian tail.

Related audio

Supplementary information

Simulation of beam-driven plasma wakefield acceleration

The video shows 120 successive frames from a simulation of the electron beam‐driven plasma wakefield acceleration process using the 3D particle-in-cell code QuickPIC9,10. The input beam and plasma parameters are based on those of the experiment. The upper frame of the movie shows a slice through the center of electron beam and plasma wake structure, where x is the dimension transverse to the motion, ξ = z-ct is the dimension parallel to the motion, and Ez is the on-axis longitudinal electric field. The plasma electron density is represented in blue, while the beam density is represented in red. The ion density (now shown) is uniform. The lower frame of the video shows the evolution of the longitudinal phase space of the electron beam, using the color scale along the bottom for the beam charge density. The video depicts the beam-plasma interaction over the full length of the plasma source, including propagation before and after the 10cm plasma density ramps on either end of the 26cm flat-top density region. (MOV 9133 kb)

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Litos, M., Adli, E., An, W. et al. High-efficiency acceleration of an electron beam in a plasma wakefield accelerator. Nature 515, 92–95 (2014).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing