Observations of magnetic reconnection between colliding plumes of magnetized laser-produced plasma are presented. Two counter-propagating plasma flows are created by irradiating oppositely placed plastic (CH) targets with 1.8 -kJ, 2 -ns laser beams on the Omega EP Laser System. The interaction region between the plumes is pre-filled with a low-density background plasma and magnetized by an externally applied magnetic field, imposed perpendicular to the plasma flow, and initialized with an X-type null point geometry with B = 0 at the midplane and B = 8 T at the targets. The counter-flowing plumes sweep up and compress the background plasma and the magnetic field into a pair of magnetized ribbons, which collide, stagnate, and reconnect at the midplane, allowing the first detailed observations of a stretched current sheet in laser-driven reconnection experiments. The dynamics of current sheet formation are in good agreement with first-principles particle-in-cell simulations that model the experiments.PACS numbers: 52.27.-h, 52.35.Vd, 52.65. Rr, 52.72.+v, 94.30.cp Throughout the Universe, magnetic reconnection allows the magnetic field to change its topology and thereby allow an explosive release of stored energy [1][2][3]. Recently, a number of experiments have been carried out studying magnetic reconnection using laser-driven plasmas [4][5][6][7][8]. These experiments are in many ways complementary to traditional reconnection experiments with magnetized discharge plasmas [3]. Some notable features include the high plasma beta, strong inflows, and strong magnetic flux pile-up. This regime is very interesting as there are a number of space and astrophysical contexts where supersonic, magnetized flows collide, such as interactions of planetary magnetospheres with the solar wind [9], interaction of the solar wind with the interstellar medium at the heliopause [10,11], and pulsar windtermination shocks [12], to name only a few.Previous laser-driven experiments studied the reconnection of the self-generated (e.g., Biermann battery) magnetic fields between colliding laser-produced plasma plumes [4][5][6][7][8]. Magnetic field annihilation [5] has been observed, as well as plasma jets [4,[6][7][8] and electron energization [8]. This Letter presents, for the first time, results on reconnection of an externally applied magnetic field by counter-propagating, laser-driven colliding highenergy density (HED) plasmas. These experiments are based on new techniques for externally controlled magnetization of ablated plasma plumes. The geometry of this externally magnetized plasma experiment makes it amenable to end-to-end simulation with particle-in-cell codes modeling the entire progression of the experiment, including plasma formation and assembly of the current sheet. While previous results in HED plasmas could infer reconnection through annihilation of the magnetic field [5], this work is the first to observe clear stagnation of the counter-propagating magnetized ribbons and the formation of an extended reconnection layer. T...

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A laser-driven, magnetized liner inertial fusion (MagLIF) experiment is designed for the OMEGA Laser System by scaling down the Z point design to provide the first experimental data on MagLIF scaling. OMEGA delivers roughly 1000× less energy than Z, so target linear dimensions are reduced by factors of ∼10. Magneto-inertial fusion electrical discharge system could provide an axial magnetic field of 10 T. Two-dimensional hydrocode modeling indicates that a single OMEGA beam can preheat the fuel to a mean temperature of ∼200 eV, limited by mix caused by heat flow into the wall. One-dimensional magnetohydrodynamic (MHD) modeling is used to determine the pulse duration and fuel density that optimize neutron yield at a fuel convergence ratio of roughly 25 or less, matching the Z point design, for a range of shell thicknesses. A relatively thinner shell, giving a higher implosion velocity, is required to give adequate fuel heating on OMEGA compared to Z because of the increase in thermal losses in smaller targets. Two-dimensional MHD modeling of the point design gives roughly a 50% reduction in compressed density, temperature, and magnetic field from 1-D because of end losses. Scaling up the OMEGA point design to the MJ laser energy available on the National Ignition Facility gives a 500-fold increase in neutron yield in 1-D modeling.