Towards a hypervelocity optical track microparticle accelerator: Theory and initial validation experiments

Abstract

We propose an optical track accelerator for generating hypervelocity beams of neutral microparticles. In this scheme, projectiles (dielectric microspheres from 1 to 20 μm in diameter) are fed into the hollow core of an optical fiber, stabilized against wall collisions, and accelerated along its length, all using a single laser. Theoretically, efficient light-to-matter momentum transfer (>50% typical, 200% theoretical limit) over a relatively long diffraction-free distance (>10 m) should enable exit velocities exceeding 10 km/s with existing technologies. This novel approach may produce highly directional beams of particles in arbitrary charge states, with uniform sizes and velocities, which can be used to approximate micrometeors in space, terrestrial dust particles, or cold spray powders. Thus, successful demonstration of such an instrument would have application across many high-impact research areas, including but not limited to space debris mitigation, hypersonic ablation, very-low-earth-orbit spaceflight, and additive manufacturing. This architecture takes advantage of rapid concurrent advances in the fields of high-energy lasers and hollow-core optical fibers with high power-handling capability, anticipating their continued growth. In this work, we present an analysis estimating the predicted capabilities of this system, a developmental roadmap for reaching certain velocity milestones, and two sets of experimental results, which validate our models and system concept at low exit velocities of ∼1−10 cm/s.