HEATING A PLASMA BY A BROADBAND STREAM OF FAST ELECTRONS: FAST IGNITION, SHOCK IGNITION, AND Gbar SHOCK WAVE APPLICATIONS
Gus'kov S.Yu., Nikolai Ph., Ribeyre X., Tikhonchuk V.T.

Received: January 12, 2015

DOI: 10.7868/S0044451015090175

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An exact analytic solution is found for the steady-state distribution function of fast electrons with an arbitrary initial spectrum irradiating a planar low-Z plasma with an arbitrary density distribution. The solution is applied to study the heating of a material by fast electrons of different spectra such as a monoenergetic spectrum, a step-like distribution in a given energy range, and a Maxwellian spectrum, which is inherent to laser-produced fast electrons. The heating of shock- and fast-ignited precompressed inertial confinement fusion (ICF) targets as well as the heating of a target designed to generate a Gbar shock wave for EOS experiments by laser-produced fast electrons with a Maxwellian spectrum is investigated. A relation is established between the energies of two groups of Maxwellian fast electrons, which are responsible for generation of a shock wave and heating the upstream material (preheating). The minimum energy of the fast and shock igniting beams as well as of the beam for a Gbar shock wave generation increases with the spectral width of the electron distribution.