Conventional electron linear accelerators are essential research tools but limited in providing high beam currents. Energy recovery technology enables high beam currents with reasonable and sustainable power supply requirements by recycling the electrons’ kinetic energy. Independently, higher beam energies can be achieved if electrons are accelerated multiple times in a linear accelerator. The combination of both techniques results in a multi-turn energy recovery linear accelerator, which is capable of providing high beam power. Here we report the demonstration of efficient energy recycling in multi-turn operation where we saved up to 87% of the consumed beam power in the main linear accelerator of the superconducting Darmstadt electron linear accelerator (S-DALINAC). In this setting, the cumulative phase slippage effect, caused by the different speeds of the electrons per main linear accelerator pass and the resulting different interactions with the alternating electric field, cannot be neglected and was compensated. Our proof-of-principle demonstration shows how multi-turn energy recovery linear accelerators can outperform conventional machines due to the potential for considerable power saving while providing higher beam power.
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The experimental data presented in this manuscript are available from a TUdatalib repository43. Source data are provided with this paper.
The codes that support the findings of this study are available from a TUdatalib repository37.
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We thank J. Enders and F. Hug for discussions and assistance. This work was supported by the German Research Foundation within the research training group GRK 2128 AccelencE (project ID 264883531) (F.S., M.A., L.J., N.P., M.D., M.F., R.G., M.S., L.S. and S.W.), the German Federal Ministry for Education and Research under grant no. 05H21RDRB1 (F.S., M.A., L.J., N.P. and M.D.) and the State of Hesse under the grant Nuclear Photonics within the LOEWE programme (M.A., N.P. and M.S.) and within the Hessian Research Cluster Project ELEMENTS (project ID 500/10.006) (M.A., L.J., N.P., M.F. and R.G.).
The authors declare no competing interests.
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Extended Data Fig. 1 Simulated longitudinal phase space along the accelerator.
Visualization of the momentum deviation, Δp, and time deviation, Δt, relative to the centroid values. Each frame provides the value for the location, s, as well as a description of the location behind which the plotted phase space is present. Cavity j in main-LINAC pass i is indicated as ‘Cavity (i,j)’. In this figure, a recirculation (rec.) ends directly in front of the first cavity of the main LINAC. In the last two frames, the correlated phase space at first entry into the main LINAC is compared to the phase space after maximum acceleration and at the end of the last main-LINAC pass, respectively.
Extended Data Fig. 2 Simulated longitudinal quantities along the accelerator.
Visualization of the centroid momentum, \(\bar p\), the momentum spread, σδ, and the bunch length, σt, as function of the location, s, starting after the injector LINAC. The bunch length is changing due to different velocities of the electrons and due to different path lengths of the electrons caused by the longitudinal dispersion. The effect of the longitudinal dispersion is implemented in the simulations by elements of zero length at the end of the corresponding sections.
Source Data for Fig. 3
Source Data Extended Data Fig. 1
Source Data Extended Data Fig. 2
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Schliessmann, F., Arnold, M., Juergensen, L. et al. Realization of a multi-turn energy recovery accelerator. Nat. Phys. 19, 597–602 (2023). https://doi.org/10.1038/s41567-022-01856-w
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