HIF transport issues for P≳10-3 Torr and Z≳1

Final transport schemes for HIF are examined, with emphasis on transport for p≳10^-3 Torr and Z≳1 since this should simplify the reactor design and reduce the length of the accelerator. Specifically the question of charge neutralization is addressed. We find (1) the fractional neutralization f needed scales as f_i=(1-Z^-2) which means f_i≳0.89 is needed for Z≳3; (2) axially-trapped electrons limit the net beam potential to eφ_min=α(1/2 m_ev_i²) with 1≤α≲4; (3) radially-expelled plasma ions increase f_i especially near the pellet; (4) radially-oscillating plasma electrons have and adiabatic limit of f_i≊0.5; and (5) as f_i approaches unity, plasma particle trajectories may involve drift motions along and radially away from the ion beam. Also, criteria are given for the maximum Z/A allowed for transporting very large currents. For the HIF parameters used, it appears that neutralization will probably be adequte for Z≲3.