Efficient Generation of Neutrons Based on Ultrashort Laser-driven Direct Acceleration in Microwire-Array Targets

We report on an experimental demonstration of efficient neutron generation based on direct laser acceleration in microwire-array targets irradiated by ultrashort (tens of femtoseconds) laser pulses. The optimal array period was identified, at which the maximum proton energy and the number of protons with energies exceeding 1~MeV were significantly increased. Using a 1~PW, ~25~fs laser at a moderate intensity of ~10²⁰~W/cm², a high neutron yield of up to (8.33±0.84)×10⁶~n/sr/J was detected from the LiD converter via ⁷Li(p,n) and D(p,n+p) nuclear reactions. Self-consistent integrated simulations reproduced the experimental results and predicted that with a Be converter, a forward pulsed neutron source with an unprecedented yield per joule of 3.67×10⁷~n/sr/J can be obtained under identical laser conditions. This type of neutron source is favorable for applications that require a high repetition rate utilizing compact and economical laser systems.