SABRE extraction ion diode results and the prospects for eight ion inertial fusion energy drivers

Summary form only given. We have found that the ion source has a profound impact on ion diode performance. The production of pre-formed lithium ion sources required for fusion has been more difficult than anyone ever imagined under typical pulsed-power conditions. We have used a laser at 40 to 80 MW/cm/sup 2/ to pre-form, for the first time, non-protonic plasmas from a LiAg anode film, and in-situ deposited Li films. Ion beams have also been generated from carbon surfaces with this laser. We observe a 20 ns earlier turn on of current, at a Child-Langmuir level, and the best impedance history that we have ever produced with an enhancement below 4, and no impedance collapse for up to 45 ns. This impedance history may be acceptable to drive the 2nd stage of a two-stage system. Divergence in these experiments may have been dominated by laser and source non-uniformity. Also, the ion beams produced were either dominated by contaminant ions for the case of Li, or by a charge-state spread in the case of carbon. We have discovered nothing however, to indicate that simultaneously achieving the requisite divergence, current density, and impedance history is fundamentally impossible.