Using Relativistic Intensity Laser Pulses to Generate Huge Magnetic Fields and a Magnetic Reconnection Geometry
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The 2018 Nobel Prize in Physics technique of chirped pulse amplification (CPA) can be used to produce light pulses that can be focused to intensities where the electric field oscillates electrons at relativistic velocities. The currents due to the relativistic electrons can generate huge, dynamic fields within a laboratory plasma. Plasma dynamics in astrophysical plasmas are strongly impacted by magnetic field topology. However, direct measurements of the outer space plasma conditions and fields are challenging, so laboratory studies of magnetic dynamics and reconnection provide an important platform for testing theories and characterizing different regimes. The extremely energetic class of astrophysical phenomena – including high-energy pulsar winds, gamma ray bursts, and jets from galactic nuclei – have plasma conditions where the energy density of the magnetic fields exceeds the rest mass energy density (cold = B2/(µ0nemec2) > 1, the cold magnetization parameter). I will show experimental measurements, along with numerical modeling, of short-pulse, high-intensity laser-plasma interactions that produce extremely strong magnetic fields (>100 T) in a plasma such that cold > 1. The generation and the dynamics of these magnetic fields under different target conditions was studied, and relativistic intensity laser-driven, magnetic reconnection experiments were performed. I'll describe how X-ray imaging allows the observation of the fast electron dynamics. Evidence of magnetic reconnection was identified by the plasma's X-ray emission patterns, changes to the electron spectrum, and by measuring the reconnection timescales.