Fast neutron yield from relativistic irradiation of micron scale plumes generated via microfluidic surface wave acoustic nebulizer

Reduced mass targets consisting of gas-phase clusters, droplets and microjets have all been successfully employed as sources of energetic ion beams driven through intense laser plasma interactions. A high-brightness tabletop neutron source (10^7-9 n/sr/sec) is desirable for radiographic applications but would require scaling targets to multi-kHz operation with TW/kW drivers. Practical realization thus far has been limited by complex cryogenic systems and rigorous demands placed on vacuum throughput. Relativistic irradiation of atomized deuterated droplets in a pitcher-catcher configuration results in favorable D(d,n)³He fusion cross sections in the mixed regime between coulombic explosion and target normal sheath acceleration. Our experiments explore this transitional mass-limited target regime and present the first demonstration of an in-chamber aerosol plume generator based on standing wave surface acoustic wave nebulization (SW-SAWN) with solid-state LiNbO₃ devices. Deuteron acceleration from 1-4 μm droplet plumes is explored with relativistic (>10¹⁸ W/cm²) Ti:Sa pulses at ½ kHz. Isotropic yield from D-D fusion is characterized via fast neutron time-of-flight. Pulse chirp and pure helium backfill are investigated as parameters enabling vacuum-free source operation at near atmospheric pressures.