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A high-intensity laser irradiating a few-μm solid foil will accelerate ions from the bulk of the target as well as protons from a surface contaminant layer. Experimental measurements of ion spectra using the OMEGA EP laser (0.25–1 kJ, 10 ps) show, as suggested previously [Petrov et al., Phys. Plasmas 17, 103111 (2010)1070-664X10.1063/1.3497002], that at a laser fluence exceeding 1 J/μm^{2}, the contaminant layer is accelerated enough that ions from the bulk of the target are more effectively accelerated. When using CD_{2} as a target, the high fluence results in a 100-fold increase in deuteron acceleration efficiency (near 1% of laser energy) compared to subthreshold fluence. This is found to be due to the fact that the deuterons have a higher density at many locations during acceleration, allowing a larger electric field to develop, leading to improved efficiency. Using a pitcher-catcher setup, these deuterons, as well as protons from the contaminant layer, strike a LiF target and generate neutrons via (d,n) and (p,n) nuclear reactions. CR39 plastic and nuclear activation detectors measured broadband neutron yields of 4×10^{9}sr^{−1} and yields of 10^{8}sr^{−1} for neutrons above 11 MeV.

The periodical change of the Crab nebula’s jet direction challenges our understanding of astrophysical jet dynamics. Here the authors use high-power lasers to create a jet that can be directly compared to the Crab nebula’s, and report the detection of plasma instabilities that mimic kink behaviour.

Energy spectra and spectrally resolved one-dimensional fluence images of self-emitted charged-fusion products (14.7 MeV D ^3 He protons) are routinely measured from indirectly driven inertial-confinement fusion (ICF) experiments utilizing ignition-scaled hohlraums at the National Ignition Facility (NIF). A striking and consistent feature of these images is that the fluence of protons leaving the ICF target in the direction of the hohlraum's laser entrance holes (LEHs) is very nonuniform spatially, in contrast to the very uniform fluence of protons leaving through the hohlraum equator. In addition, the measured nonuniformities are unpredictable, and vary greatly from shot to shot. These observations were made separately at the times of shock flash and of compression burn, indicating that the asymmetry persists even at ∼0.5–2.5 ns after the laser has turned off. These phenomena have also been observed in experiments on the OMEGA laser facility with energy-scaled hohlraums, suggesting that the underlying physics is similar. Comprehensive data sets provide compelling evidence that the nonuniformities result from proton deflections due to strong spontaneous electromagnetic fields around the hohlraum LEHs. Although it has not yet been possible to uniquely determine whether the fields are magnetic ( B ) or electric ( E ), preliminary analysis indicates that the strength is ∼1 MG if B fields or ∼10 ^9 V cm ^−1 if E fields. These measurements provide important physics insight into the ongoing ignition experiments at the NIF. Understanding the generation, evolution, interaction and dissipation of the self-generated fields may help to answer many physics questions, such as why the electron temperatures measured in the LEH region are anomalously large, and may help to validate hydrodynamic models of plasma dynamics prior to plasma stagnation in the center of the hohlraum.