Ionization-induced electron trapping in ultrarelativistic plasma wakes

Area of Science:

• Plasma physics
• High-energy particle acceleration

Background:

• Investigating electron trapping mechanisms in relativistic plasma wakes is crucial for advancing particle accelerators.
• Understanding electron behavior within beam-driven plasma wakes informs the design of next-generation acceleration technologies.

Purpose of the Study:

• To investigate the onset of electron trapping in a highly relativistic, 3D beam-driven plasma wake.
• To determine the critical wake amplitude for initiating electron trapping.

Main Methods:

• Utilized a 3D beam-driven plasma wake in a Lithium (Li) plasma confined by Helium (He) gas.
• Observed electron trapping as a function of increasing wake amplitude.
• Employed Particle-In-Cell (PIC) simulations and an analytical model for comparison.

Main Results:

• Electron trapping was observed in the transition regions of the Li-He plasma.
• The onset of trapping was linked to the wake amplitude.
• Electrons achieved energy gains up to 7.6 GeV over a 30.5 cm plasma length.
• The experimentally inferred trapping threshold was 36 GV/m.

Conclusions:

• The study successfully identified the onset conditions for electron trapping in a relativistic plasma wake.
• Experimental findings align well with analytical models and PIC simulations, validating the proposed trapping mechanism.
• This research provides critical insights into controlling and optimizing electron acceleration in plasma-based accelerators.