Fast Neutron Generation from Ultrafast Spatially and Temporally Coherently Combined Fiber Laser Driver

To date the architecture of most laser driven neutron sources are designed around high pulse energy (>100mJ) laser systems; however, the neutron flux of these systems is limited by their repetition rate of 1-10Hz. We are developing a new ultrashort fiber laser based driver architecture which delivers high pulse energies at kHz repetition rates, suitable for driving both high flux particle sources and allowing for real time feedback control to achieve optimized system performance. Our demonstration system currently achieves pulses with energies of tens of millijoules at a 2kHz repetition rate by simultaneously incorporating spatial and temporal coherent combining techniques. As a practical demonstration of this unique architecture for scientific applications, we show coincident isotropic fast neutron generation via D(d,n)³He fusion reactions in a free-flowing microscale deuterated liquid jet target. To our knowledge, this is the first fast neutron source driven by a fiber laser system. This proof-of-principle experimental demonstration with near-relativistic pulses highlights the potential for increased scaling of the fluxes of particle accelerators and secondary radiation sources as this fiber technology matures towards multiple joule pulses at several kilohertz. This work is funded under DOE Advanced Accelerator Stewardship Grant FP00013287 and DOE Grant DE-SC0016804