1. Control of Electron Beam Using Strong Magnetic Field for Efficient Core Heating in Fast Ignition
Tomoyuki Johzaki*, *Hiroshima University
Energy density
(Bx2+By2)1/2
[kT]
Log10(gne/ncr)
Even for the converging B-fields, the fast electron beam is collimated by converging field, and the resultant core temperature are enhanced in electron driven fast ignition.
2D collisional PIC simulations with converging B-field (mirror ratio Rm =5,10) for IL=3x1019W/cm2 1ps pulse,
The fast electron (FE) beam guiding and focusing around the beam axis for the moderate converging mirror fields are more effective compared with uniform B-field (3kT) case.
The “magnetic pipe” structure is formed due to the collisional effects.
2D (cylindrical geo.) particle-hydro simulations with compressed B-field obtained from fuel shell implosion (Rm >100 at the center of core; hot spot),
The coupling ratio of FE to core becomes smaller than that obtained without external B-fields because of beam reflection due to the mirror fields.
But, locally , the heating rate in the part of the dense main fuel (faces to the beam injection side) is enhanced, which leads to enhancement of neutron weighted temperature.
These figures show the temporal evolution of spatial profiles of beam energy density and strength of magnetic field on this plane for case 1, RM = 5. Here, Bz is not included.
In this case, part of the fast electrons are scattered or reflected due to the mirror fields, but the around the beam axis, beam can be collimated along the magnetic field lines. Also, the magnetic pipe like structure is observed.