Magnetic reconnection is a fundamental plasma process involving an exchange of magnetic energy to plasma kinetic energy through changes in the magnetic field topology. In many astrophysical plasmas magnetic reconnection plays a key role in the release of large amounts of energy [1], although making direct measurements is challenging in the case of high-energy astrophysical systems such as pulsar wind emissions [2], gamma-ray bursts [4], and jets from active galactic nuclei [5]. Therefore, laboratory studies of magnetic reconnection provide an important platform for testing theories and characterising different regimes. Here we present experimental measurements as well as numerical modeling of relativistic magnetic reconnection driven by short-pulse, high-intensity lasers that produce relativistic plasma along with extremely strong magnetic fields. Evidence of magnetic reconnection was identified by the plasma's X-ray emission patterns, changes to the electron energy spectrum, and by measuring the time over which reconnection occurs. Accessing these relativistic conditions in the laboratory allows for further investigation that may provide insight into unresolved areas in space and astro-physics.

Experiments at the HERCULES laser facility have produced directional neutron beams with energies up to 16.8(±0.3) MeV using d12(d,n)23He,Li73(p,n)47Be,andLi37(d,n)48Be reactions. Efficient Li12(d,n)48Be reactions required the selective acceleration of deuterons through the introduction of a deuterated plastic or cryogenically frozen D2O layer on the surface of a thin film target. The measured neutron yield was ≤1.0 (±0.5)×107 neutrons/sr with a flux 6.2(±3.7) times higher in the forward direction than at 90°. This demonstrates that femtosecond lasers are capable of providing a time averaged neutron flux equivalent to commercial d12(d,n)23He generators with the advantage of a directional beam with picosecond bunch duration.

Experiments on the interaction of an ultra-short pulse laser with heavy-water, ice-covered copper targets, at an intensity of 2×1019 W/cm2, were performed demonstrating the generation of a “pure” deuteron beam with a divergence of 20°, maximum energy of 8 MeV, and a total of 3×1011 deuterons with energy above 1 MeV—equivalent to a conversion efficiency of 1.5% ± 0.2%. Subsequent experiments on irradiation of a B10 sample with deuterons and neutron generation from d-d reactions in a pitcher-catcher geometry, resulted in the production of ∼106 atoms of the positron emitter C11 and a neutron flux of (4±1)×105 neutrons/sterad, respectively.