Publications by authors named "N J Fisch"

Hot plasma is highly conductive in the direction parallel to a magnetic field. This often means that the electrical potential will be nearly constant along any given field line. When this is the case, the cross-field voltage drops in open-field-line magnetic confinement devices are limited by the tolerances of the solid materials wherever the field lines impinge on the plasma-facing components.

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We report the observation of longitudinal filamentation of an electron-positron pair plasma in a beam-driven QED cascade. The filaments are created in the "pair-reflection" regime, where the generated pairs are partially stopped and reflected in the strong laser field. The density filaments form near the center of the laser pulse and have diameters similar to the laser wavelength.

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By producing localized wave regions at the ends of an open-field-line magnetic confinement system, ponderomotive walls can be used to differentially confine different species in the plasma. Furthermore, if the plasma is rotating, this wall can be magnetostatic in the laboratory frame, resulting in simpler engineering and better power flow. However, recent work on such magnetostatic walls has shown qualitatively different potentials than those found in the earlier, nonrotating theory.

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Article Synopsis
  • Shorter-wavelength lasers can achieve high intensities with low energy if they are focused to small spots and short durations.
  • Currently, the most accessible laser pulse energies are much higher for near-optical wavelengths compared to shorter wavelengths.
  • An efficient way to transfer energy from these higher near-optical wavelengths to shorter wavelengths may involve six-photon resonant scattering within plasma, which could enhance the frequency conversion needed for higher laser intensities.
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