Magnetic field guiding of electron beam for reduction of ignition requirement in fast ignition laser fusion*

One of most important issues in fast ignition laser fusion is efficient core heating by laser produced relativistic electron beam (REB). The large angular divergence of REB, however, inhibits the efficient core heating[1]. To solve this problem, the beam guiding using externally applied kilo-tesla class magnetic field has been proposed [2], and its availability has been numerically[3] and experimentally[4] demonstrated. The effect of external field is not only beam guiding, but also the effective range reduction due to Larmor motion. In addition, the convergence field configuration is formed through implosion, then the beam focusing is also expected for the moderate mirror ratio case. On the basis of hybrid simulation, we will show the enhancement in heating efficiency and reduction in ignition threshold due to external fields.

[1] S. Fujioka, et al., Phys. Rev. E 91, 063102 (2015).

[2] D. J. Strozzi et al., Phys Plasmas 19, 072711 (2012).

[3 ]T. Johzaki, et al., Plasma Phys. Control. Fusion 59, 014045 (2017).

[4]M. Bailly-Grandvaux, et al., Nat. Commun. 9, 102 (2018).