Focusing of keV Ion Beams from Plasma with Micro-Glass Capillaries Beyond the Self-Focusing Limit: Realization of Quantum Ion Beams

Micro-glass capillaries have emerged as a crucial tool for lossless guiding and focusing of ion beams [1–4]. The key mechanism for ion beam guiding and self-focusing relies on the distributions of charged patches on the capillary inner wall induced by the incident beam [1]. However, it has been observed that, in focusing intense ion beams through glass capillaries, the space charge force surpasses the self-focusing force [4], thereby establishing a limit in the self-focusing capability [5]. Consequently, focusing ion beams beyond this self-focusing limit has proven to be a significant challenge.