Resistive Collimation of Electron Beams in Laser-Produced Plasmas

Intense relativistic electron beams, produced by high-intensity short-pulse laser irradiation of a solid target, have many potential applications including fusion by fast ignition. Using a unique Fokker-Planck code, supported by analytic calculations, we show that fast electrons can be collimated into a beam even when the fast electron source is not strongly anisotropic, and we derive a condition for collimation to occur.

Figure 1

Spatial plots (close to the axis) of temperature (a)–(c) and (g)–(i) for parameters given in Table . (d)–(f), respectively, plot the magnetic field for cases (a)–(c). The temperature contour levels are 350, 400, 600, 800, 1000, 1200, 1400, 1800, 2200, and 2600 eV. The magnetic field contour levels are $+/-0.1$, 0.2, 0.5, 1.0, 1.5, and 2.0 MG.

Figure 2

Time dependence of the maximum magnetic field calculated by KALOS and the value estimated by the approximate calculation with $T_{\mathrm{i}\mathrm{n}\mathrm{i}\mathrm{t}}=0.5\mathrm{k}\mathrm{e}\mathrm{V}$ and $T_{\mathrm{i}\mathrm{n}\mathrm{i}\mathrm{t}}=1.5\mathrm{k}\mathrm{e}\mathrm{V}$.