Observation of Ion Motion in Plasma Wakefield Accelerators
- Alexandra Welsch
- May 2
- 1 min read
A recent study led by Marlene Turner and a team of researchers from the international AWAKE collaborations has provided new insights into the behaviour of ions within plasma wakefield accelerators. Their findings, published in Physical Review Letters, reveal that ion motion in these accelerators inversely correlates with the plasma ion mass. This motion manifests as a "bunch tail," occurring when sufficient ion movement suppresses wakefields.
Plasma wakefield accelerators utilize plasma electrons oscillating collectively in a background of positively charged plasma ions to generate accelerating structures. While these accelerators can achieve gradients much higher than traditional radio-frequency cavities, they often assume plasma ions are immobile and uniformly distributed. However, this study challenges that assumption by demonstrating that ion motion, driven by the ponderomotive force of wakefields, significantly impacts accelerator performance.
The researchers observed that the ion motion effect depends on the plasma ion mass, appearing first with lighter ions. They also found that increasing the amplitude of wakefields, achieved by varying the drive bunch charge, enhances this effect. These observations align with theoretical predictions and simulations, suggesting that ion motion can influence the efficiency and stability of plasma-based acceleration processes.
Understanding these dynamics is crucial for advancing plasma wakefield acceleration technology, which holds promise for compact and efficient particle accelerators in various applications.
More information:
M. Turner et al., “Experimental Observation of the Motion of Ions in a Resonantly Driven Plasma Wakefield Accelerator”, Phys. Rev. Lett. 134, 155001 (2025)
