Progress on astrophysical collisionless shock experiments on Omega and NIF*

We report the latest experimental progress on our laboratory experiments using the Omega and NIF lasers to investigate the dynamics of high Mach number collisionless shock formation in two interpenetrating plasma streams. It is believed that in astrophysical environments such shocks generate and amplified magnetic fields and accelerate cosmic rays. Counterstreaming plasma flows generated by laser ablation have been probed on the Omega laser using proton radiography, showing the formation, growth, and merger of filamentary magnetic field structures associated with the Weibel instability in a collisionless regime [1]. Recently, higher-energy experiments using the NIF laser showed enhanced heating when the flow interaction transited from collisional to collisionless flows [2]. The latest experiments on NIF considerably reduced collisionality and increased interaction volume. Significantly enhanced neutron production and high energy electrons were observed. We will present these recent experimental results. [1] C. M. Huntington, et al., Nature Physics, 11, 173 (2015); [2] J. S. Ross et al., Phys. Rev. Lett., 118, 185003 (2017).