High-repetition neutron generation from ultrashort laser pulse irradiation of electrohydrodynamically dispensed deuterated microdroplets*

We report initial findings of laser-driven fusion neutron yield from the interaction of regeneratively amplified several-mJ, 35 fs laser pulses at 1/2 kHz with spatio-temporally resolved microdroplets from a novel electrohydrodynamic jet nozzle. Femtoliter-scale deuterated droplet targets are produced via pulsed high-voltage electrostatic extraction from a 50$\mu m$ I.D./120$\mu m$ O.D. stainless steel capillary. High intensity laser pulses (of order 10$^{19}$ W/cm$^{2}$) are focused under vacuum and collide with the microdroplets to create energetic deuterons via the Target Normal Sheath Acceleration (TNSA) mechanism. 2.45 MeV neutron pulses are generated via the \textbf{d\emph{(d,n)}$^{3}$He} fusion half-reaction. Neutron flux is measured via zero gamma sensitivity calibrated bubble detectors while neutron spectrum is quantified with plastic scintillators in a pulse-shape discrimination neutron time-of-flight (ToF) setup. To our knowledge, this experiment is the first to demonstrate micron-scale monodisperse droplet generation in vacuum utilizing pulsed electrohydrodynamic jetting.