Electron-beam transport for inertial fusion

Two methods for transporting electron beams from the diode to a pellet are analyzed. First, pinched beams can propagate along a Z pinch with current density Jb≲ν/γJp, where Jp is the pinch current density. Heavy high-density (∼1018cm−3) gas is required in order to (1) reduce plasma turbulence that could prevent total current neutralization and (2) prevent expansion of the pinch by transverse beam pressure. Second, compression in a magnetic mirror with multiple reflections between diode and mirror is considered. Reflex diode current density enhancements ≳100 above Child’s law are required for this approach to succeed.