Energy Depletion and Re-Acceleration of Driver Electrons in a Plasma-Wakefield Accelerator

Abstract

For plasma-wakefield accelerators to fulfil their potential for cost effectiveness, it is essential that their energy-transfer efficiency be maximized. A key aspect of this efficiency is the near-complete transfer of energy, or depletion, from the driver electrons to the plasma wake. Achieving full depletion is limited by the process of re-acceleration, which occurs when the driver electrons decelerate to non-relativistic energies, slipping backwards into the accelerating phase of the wakefield and being subsequently re-accelerated. Such re-acceleration is unambiguously observed here for the first time. At this re-acceleration limit, we measure a beam driver depositing (57 $\pm$ 3)\% of its energy into a 195-mm-long plasma. Combining this driver-to-plasma efficiency with previously measured plasma-to-beam and expected wall-plug-to-driver efficiencies, our result suggests that plasma-wakefield accelerators can in principle reach or even exceed the energy-transfer efficiency of conventional accelerators.

Manuscript: 7 pages, 4 figures; Supplementary material: 3 pages, 1 figure

References in corpus (6)

• Single-Shot Characterization of High Transformer Ratio Wakefields in Nonlinear Plasma Acceleration
• HiPACE++: a portable, 3D quasi-static Particle-in-Cell code
• Saturation of the hosing instability in quasi-linear plasma accelerators
• Emittance preservation in a plasma-wakefield accelerator
• Evolution of longitudinal plasma-density profiles in discharge capillaries for plasma wakefield accelerators
• Matching small $\beta$ functions using centroid jitter and two beam position monitors

Cited by in corpus (3)

• Correlations between X-rays, Visible Light and Drive-Beam Energy Loss Observed in Plasma Wakefield Acceleration Experiments at FACET-II
• Longitudinally resolved measurement of energy-transfer efficiency in a plasma-wakefield accelerator
• Slice Emittance Preservation and Focus Control in a Passive Plasma Lens