Beam Realignment with Emittance Preservation in a Plasma Wakefield-Accelerator Stage

Area of Science:

• Plasma physics
• Particle accelerators
• Beam dynamics

Background:

• Plasma-based accelerators use drive beams to create wakes for accelerating witness beams.
• Beam misalignment in linear colliders causes hosing instability and emittance growth, hindering beam collision.
• High-charge, small-spot electron beams induce nonlinear focusing forces due to ion motion.

Purpose of the Study:

• To investigate the use of drive-beam-induced ion motion to suppress witness beam hosing and achieve realignment.
• To assess the impact of this method on beam quality, including emittance and energy spread.
• To evaluate the energy transfer efficiency in plasma acceleration stages.

Main Methods:

• Utilized fully self-consistent qpad simulations.
• Modeled plasma stages with quasi-adiabatic plasma density ramps.
• Analyzed beam dynamics under nonlinear focusing forces from driven ion motion.

Main Results:

• Demonstrated the elimination of witness beam hosing and successful realignment with the drive beam.
• Achieved simultaneous beam matching with a centroid offset reduction.
• Observed approximately 4% emittance growth and <1% energy spread growth.
• Reported a 50% energy transfer efficiency.

Conclusions:

• Drive-beam-induced ion motion is an effective technique for controlling witness beam hosing and misalignment.
• This method offers a viable solution for improving beam quality in plasma-based linear colliders.
• The simulations show a promising balance between instability mitigation and beam quality preservation.